CN116800345A

CN116800345A - Coherent receiving apparatus, coherent transmitting apparatus, and coherent communication system

Info

Publication number: CN116800345A
Application number: CN202210272429.0A
Authority: CN
Inventors: 李良川; 桂韬; 曹军涛
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2022-03-18
Filing date: 2022-03-18
Publication date: 2023-09-22
Also published as: WO2023174165A1

Abstract

The application provides a coherent receiving device, a coherent transmitting device and a coherent communication system, and belongs to the technical field of optical communication. The coherent receiving device comprises a polarization control module and a data receiving module. The polarization control module is used for receiving first local oscillation light, the first local oscillation light comprises a first light beam and a second light beam with orthogonal polarization states, the wavelength of the first light beam is the first wavelength, the wavelength of the second light beam is the second wavelength, and the first local oscillation light is divided into the first light beam and the second light beam by controlling the polarization state of the first local oscillation light. The data receiving module is used for receiving first signal light, the first signal light comprises a third light beam modulated with data and a fourth light beam modulated with data, the wavelength of the third light beam is the first wavelength, the wavelength of the fourth light beam is the second wavelength, the first light beam is used for obtaining the data modulated on the third light beam, and the second light beam is used for obtaining the data modulated on the fourth light beam. By adopting the scheme of the application, the polarization control and tracking of dual wavelengths can be realized.

Description

Coherent receiving apparatus, coherent transmitting apparatus, and coherent communication system

Technical Field

The present application relates to the field of coherent optical communication technologies, and in particular, to a coherent receiving device, a coherent transmitting device, and a coherent communication system.

Background

In the signal transmission process, the spectrum efficiency of the coherent transmission technology is higher than that of other transmission modes, especially under the conditions of long distance and high data rate, the coherent transmission technology can not only keep excellent transmission performance, but also overcome serious loss caused by high-speed signal transmission, so that the coherent transmission technology is widely applied to submarine cables, long-distance backbones and metropolitan area transmission networks. Moreover, among the coherent transmission technologies, the homologous coherent technology has the advantages of low power consumption and low cost, so that the homologous coherent technology is widely applied to the field of signal transmission. When the signal transmission is carried out by adopting the homologous coherent technology, the polarization state of the local oscillation light directly influences the coherent receiving quality, so how to track and control the polarization state of the local oscillation light is important.

The current homologous coherent technology is applied to a 800G single-wavelength coherent communication system, but the bandwidth of an optoelectronic device is difficult to break through more than 130GB, and a 1.6T coherent communication system required in the future is easier to realize through a dual-wavelength 800G system, so that a tracking and control scheme of local oscillation light is required to be provided for the dual-wavelength coherent communication system.

Disclosure of Invention

The application provides a coherent receiving device, a coherent transmitting device and a coherent communication system, which can realize the coherent communication of dual wavelengths and can track and control local oscillation light.

In a first aspect, the present application provides a coherent receiving apparatus comprising: the device comprises a polarization control module and a data receiving module; the polarization control module is used for receiving first local oscillation light, wherein the first local oscillation light comprises a first light beam and a second light beam with orthogonal polarization states, the wavelength of the first light beam is a first wavelength, and the wavelength of the second light beam is a second wavelength; dividing the first local oscillator light into the first light beam and the second light beam by controlling the polarization state of the first local oscillator light; the data receiving module is used for receiving first signal light, wherein the first signal light comprises a third light beam modulated with data and a fourth light beam modulated with data, the wavelength of the third light beam is the first wavelength, and the wavelength of the fourth light beam is the second wavelength; the first beam is used to acquire the data modulated on the third beam and the second beam is used to acquire the data modulated on the fourth beam.

In the scheme, the polarization control module can separate the local oscillation light with two wavelengths by controlling the polarization state, and the data receiving module uses the local oscillation light with two wavelengths to respectively receive the data modulated on the signal light with two wavelengths. Thus, the coherent communication of the wavelength can be realized, and the local oscillation light can be tracked and controlled, so that the quality of coherent reception is relatively high.

In one possible implementation, the polarization control module is configured to: dividing the first local oscillator light into two light beams; and carrying out phase modulation processing on the two light beams, so that the two light beams after the phase modulation processing are the first light beam and the second light beam respectively.

In the scheme shown in the application, phase modulation processing can be used to separate local oscillation light with two wavelengths.

In one possible implementation, the polarization control module includes a first polarization beam splitting rotator (polarization splitter rotator, PSR) and a control unit; the first PSR is used for receiving a first local oscillator light and dividing the first local oscillator light into two light beams; the control unit is used for carrying out phase modulation processing on the two light beams and outputting the two light beams subjected to the phase modulation processing to the data receiving module; extracting feedback information from the phase-modulated at least one light beam; based on the feedback information, the phase modulation voltage for phase modulation processing is adjusted, so that the two light beams after phase modulation processing are the first light beam and the second light beam respectively.

In the scheme, the phase modulation voltage of the phase modulation processing is controlled by feeding back information, so that the first light beam and the second light beam can be separated more quickly and accurately.

In one possible implementation manner, the control unit includes N phase modulation units, a feedback extraction unit and a first processing module, where N is greater than or equal to 1; the N phase modulation units are used for carrying out phase modulation processing on the two light beams output by the first PSR and outputting the two light beams subjected to phase modulation processing to the data receiving module; the feedback extraction unit is used for extracting feedback information from at least one light beam after phase modulation processing; the first processing module is configured to adjust a phase modulation voltage of at least one phase modulation unit of the N phase modulation units based on the feedback information so that two light beams after phase modulation processing are the first light beam and the second light beam, respectively.

In the scheme, the phase modulation voltage of the phase modulation processing is controlled by feeding back information, so that the first light beam and the second light beam are separated more quickly and accurately.

In one possible implementation, the control unit includes a first 2×2 optical coupler, N phase modulation units, a feedback extraction unit, and a first processing module, where N is greater than or equal to 1. The first 2 x 2 optical coupler is used for receiving two light beams output by the first PSR, adjusting the rotation angles of polarization states of the two light beams, outputting two light beams, and the N phase modulation units are used for carrying out phase modulation processing on the two light beams output by the 2 x 2 optical coupler; the feedback extraction unit is used for extracting feedback information from at least one beam subjected to phase modulation processing and outputting two beams subjected to phase modulation processing to the data receiving module; the first processing module is configured to adjust a phase modulation voltage of at least one phase modulation unit of the N phase modulation units based on the feedback information, so that two light beams after phase modulation processing are the first light beam and the second light beam respectively.

In one possible implementation manner, the 1 st to the N th phase modulation units in the N phase modulation units are sequentially arranged along the local oscillation optical transmission direction, and N is greater than 1; each phase modulation unit comprises a phase modulator and a 2 x 2 optical coupler; the input port and the output port of the phase modulator in the 1 st phase modulation unit are respectively connected with one output port of the first PSR and the first input port of the 2X 2 optical coupler in the 1 st phase modulation unit; a second input port of the 2 x 2 optical coupler in the 1 st phase modulation unit is connected with the other output port of the first PSR; two output ports of the 2X 2 optical coupler in the i-1 phase modulation unit are respectively connected with the input port of the phase modulator in the i phase modulation unit and the first input port of the 2X 2 optical coupler; the output port of the phase modulator in the i-1 phase modulation unit is connected with the second input port of the 2X 2 optical coupler, i is more than 1 and less than or equal to N; two output ports of the 2X 2 optical coupler in the N phase modulation unit are respectively connected with the feedback extraction unit; the first processing module is configured to adjust a phase modulation voltage of a phase modulator in the at least one phase modulation unit based on the feedback information.

In the scheme shown in the application, the phase modulation unit is realized by the phase modulator and the 2×2 optical coupler, and the phase modulation voltage of the phase modulator is adjusted, so that the first light beam and the second light beam are separated more quickly and accurately.

In one possible implementation, the feedback extraction unit includes a first 1×2 splitter, a second 1×2 splitter, and a sub-extraction unit; the N phase modulation units are used for outputting two light beams subjected to phase modulation treatment to the first 1X 2 optical splitter and the second 1X 2 optical splitter respectively. The first 1×2 beam splitter is configured to split one beam after phase modulation into a first sub-beam and a second sub-beam, and output the first sub-beam and the second sub-beam to the data receiving module and the sub-extraction unit, respectively; the second 1×2 beam splitter is configured to split the other beam after the phase modulation processing into a third sub-beam and a fourth sub-beam, and output the third sub-beam and the fourth sub-beam to the data receiving module and the sub-extraction unit, respectively; the sub-extraction unit is configured to determine a target power, where the target power includes a sum of a power of the light of the second wavelength in the second sub-beam and a power of the light of the first wavelength in the fourth sub-beam, or includes a power of the light of the second wavelength in the second sub-beam and a power of the light of the first wavelength in the fourth sub-beam; the first processing module is configured to adjust the phase modulation voltage of the at least one phase modulation unit based on a principle of adjusting the target power to a minimum value, so that the wavelength of the first sub-beam is a first wavelength, and the wavelength of the third sub-beam is a second wavelength.

In the scheme shown in the application, the power of the light with the second wavelength in the output light path of the first light beam is determined to be minimum, and the power of the light with the first wavelength in the output light path of the second light beam is determined to be minimum, so that the light with the second wavelength is not included in the output light path of the first light beam, and the light with the first wavelength is not included in the output light path of the second light beam, therefore, the first light beam and the second light beam can be separated and then output.

In one possible implementation, the feedback extraction unit includes a first 1×2 optical splitter and a sub-extraction unit; the N phase modulation units are used for outputting two light beams subjected to phase modulation processing to the first 1 multiplied by 2 optical splitter and the data receiving module respectively. The first 1×2 beam splitter is configured to split one beam after phase modulation into a first sub-beam and a second sub-beam, and output the first sub-beam and the second sub-beam to the data receiving module and the sub-extraction unit, respectively; the sub-extraction unit is used for determining the power of the light with the second wavelength in the second sub-beam; the first processing module is configured to adjust the phase modulation voltage of the at least one phase modulation unit based on a principle of adjusting the power to a minimum value, so that the wavelength of the first sub-beam is a first wavelength.

In the scheme shown in the application, the power of the light with the second wavelength in the output light path of the first light beam is determined to be minimum, so that the light with the second wavelength is not included in the output light path of the first light beam, and the light with the first wavelength is not included in the output light path of the second light beam, therefore, the first light beam and the second light beam can be separated and then output.

In one possible implementation, the polarization state of the third beam modulated with data is orthogonal, and the polarization state of the fourth beam modulated with data is orthogonal; the data receiving module comprises a second PSR, a first wave dividing module, a second wave dividing module, a coherent receiving unit and a second processing module; the second PSR is used for receiving the first signal light and dividing the first signal light into first sub-signal light and second sub-signal light; the first branching module is used for dividing the first sub-signal light into the signal light with the first wavelength and the signal light with the second wavelength; the second wave splitting module is used for splitting the second sub-signal light into the signal light with the first wavelength and the signal light with the second wavelength; the coherent receiving unit is used for performing coherent reception on the signal light with the first wavelength by using the first light beam to obtain a first result, and performing coherent reception on the signal light with the second wavelength by using the second light beam to obtain a second result; the second processing module is configured to obtain data modulated on the third light beam and the fourth light beam based on the first result and the second result. Thus, a data receiving module is provided that implements dual wavelength coherent reception.

In a second aspect, the present application provides a coherent transmitting apparatus including a light source, a polarization changing module, and a data transmitting module; the light source is used for outputting a first light beam, a second light beam, a third light beam and a fourth light beam, wherein the wavelengths of the first light beam and the third light beam are first wavelengths, and the wavelengths of the second light beam and the fourth light beam are second wavelengths; the polarization changing module is used for combining the first light beam and the second light beam into a first local oscillation light with orthogonal polarization states and outputting the first local oscillation light; the data transmitting module is used for modulating data to the third light beam and the fourth light beam to obtain first signal light and outputting the first signal light.

In the scheme shown in the application, the polarization states of the first light beam and the second light beam are adjusted to be orthogonal and then transmitted, so that the coherent receiving device can separate the first light beam and the second light beam.

In one possible implementation manner, the data sending module comprises a processing module, a first modulator, a second modulator, a first wave combining module, a second wave combining module and a PSR; the processing module is used for providing the data; the first modulator is used for dividing the third light beam into a first sub-light beam and a second sub-light beam, and modulating data onto the first sub-light beam and the second sub-light beam respectively; the second modulator is used for dividing the fourth beam into a third sub-beam and a fourth sub-beam and modulating data onto the third sub-beam and the fourth sub-beam respectively; the first wave combining module is used for combining the first path of sub-beam modulated with data and the third path of sub-beam modulated with data into first sub-signal light; the second wave combining module is used for combining the second sub-beam modulated with data and the fourth sub-beam modulated with data into second sub-signal light; the PSR is used for adjusting the polarization state of the first sub-signal light to be orthogonal to the polarization state of the second sub-signal light, and combining the first sub-signal light and the second sub-signal light after the polarization state is adjusted to obtain the first signal light. Thus, a data transmission module for realizing dual-wavelength coherent transmission is provided.

In a third aspect, the present application provides a coherent communication system including a coherent transmitting apparatus and a coherent receiving apparatus connected by an optical fiber, the coherent transmitting apparatus including a light source, a polarization changing module, and a data transmitting module, the coherent receiving apparatus including a polarization control module and a data receiving module; the light source is used for outputting a first light beam, a second light beam, a third light beam and a fourth light beam, wherein the wavelengths of the first light beam and the third light beam are first wavelengths, and the wavelengths of the second light beam and the fourth light beam are second wavelengths; the polarization changing module is used for combining the first light beam and the second light beam into a first local oscillation light with orthogonal polarization states and outputting the first local oscillation light; the data transmitting module is used for modulating data to the third light beam and the fourth light beam to obtain first signal light and outputting the first signal light; the polarization control module is used for receiving the first local oscillation light; dividing the first local oscillator light into the first light beam and the second light beam by controlling the polarization state of the first local oscillator light; the data receiving module is used for receiving the fourth light beam; the first beam is used to acquire the data modulated on the third beam and the second beam is used to acquire the data modulated on the fourth beam.

In the scheme shown in the application, the coherent transmitting device adjusts the polarization state of the dual-wavelength local oscillation light to be orthogonal and transmits the data, and the data is transmitted through the dual-wavelength signal light. The coherent receiving device can separate local oscillation light of two wavelengths by controlling polarization states, and receives data modulated on signal light of the two wavelengths respectively by using the local oscillation light of the two wavelengths. Thus, the dual-wavelength coherent communication can be realized, and the local oscillation light can be tracked and controlled, so that the quality of the coherent communication is relatively high.

In one possible implementation, the polarization control module includes a first PSR and a control unit; the first PSR is used for receiving a first local oscillator light and dividing the first local oscillator light into two light beams; the control unit is used for carrying out phase modulation processing on the two light beams and outputting the two light beams subjected to the phase modulation processing to the data receiving module; extracting feedback information from the phase-modulated at least one light beam; based on the feedback information, the phase modulation voltage for phase modulation processing is adjusted, so that the two light beams after phase modulation processing are the first light beam and the second light beam respectively.

In one possible implementation manner, the control unit includes N phase modulation units, a feedback extraction unit and a first processing module, where N is greater than or equal to 1; the N phase modulation units are used for carrying out phase modulation processing on the two light beams output by the first PSR and outputting the two light beams subjected to phase modulation processing to the data receiving module; the feedback extraction unit is used for extracting feedback information from at least one light beam after phase modulation processing; the first processing module is configured to adjust a phase modulation voltage of at least one phase modulation unit of the N phase modulation units based on the feedback information, so that two light beams after phase modulation processing are the first light beam and the second light beam respectively.

In a fourth aspect, the present application provides a coherent communication system, including a coherent transmitting device and a coherent receiving device connected by an optical fiber; the coherent transmitting device comprises a light source, a first transmitting module, a second transmitting module, a first connecting module and a second connecting module; the coherent receiving device comprises a third connecting module, a fourth connecting module, a first polarization control module, a second polarization control module, a first receiving module and a second receiving module; the light source is used for outputting a first light beam and a second light beam to the first connecting module respectively and outputting a third light beam and a fourth light beam to the first transmitting module and the second transmitting module respectively; the first light beam and the third light beam have a first wavelength, and the second light beam and the fourth light beam have a second wavelength; the first connecting module is used for outputting the first light beam and the second light beam respectively; the first transmitting module is used for modulating data onto the third light beam to obtain first signal light, and outputting the first signal light to the second connecting module; the second transmitting module is used for modulating data onto the fourth light beam to obtain second signal light, and outputting the second signal light to the second connecting module; the second connection module is used for outputting the first signal light and the second signal light respectively; the third connection module is used for receiving the first light beam and the second light beam, sending the first light beam to the first polarization control module, and sending the second light beam to the second polarization control module; the first polarization control module is used for controlling the power difference value of the first component and the second component of the first light beam to be smaller than or equal to a reference value; the second polarization control module is used for controlling the power difference value of the first component and the second component of the second light beam to be smaller than or equal to a reference value; the fourth connection module is used for receiving the first signal light and the second signal light, sending the first signal light to the first receiving module and sending the second signal light to the second receiving module; the first receiving module is used for dividing the first signal light into two sub-signal lights and respectively acquiring data modulated on the two sub-signal lights of the first signal light by using a first component and a second component of the first light beam; the second receiving module is configured to divide the second signal light into two sub-signal lights, and acquire data modulated on the two sub-signal lights of the second signal light using the first component and the second component of the second light beam, respectively.

In the scheme shown in the application, the coherent transmitting device transmits the dual-wavelength local oscillation light and transmits data through the dual-wavelength signal light. The coherent receiving device uses two polarization control modules to respectively control the local oscillation light with double wavelengths, so that the local oscillation light with each wavelength can be separated into a first component and a second component, and the power of the first component and the power of the second component are close to or equal to each other. For a first light beam of a first wavelength, the first component is used for receiving one sub-signal light (the first polarization state when the one sub-signal light is received by the coherent receiving device) in the first signal light, the second component is used for receiving another sub-signal light (the second polarization state when the other sub-signal light is received by the coherent receiving device) in the first signal light, and the first polarization state is orthogonal to the second polarization state. For a second light beam of a second wavelength, the first component is used for receiving one sub-signal light in the second signal light, and the second component is used for receiving the other sub-signal light in the first signal light. In this way, since the powers of the first component and the second component are close to or equal to each other, it is possible to enable signal light of each orthogonal polarization state to be received.

In one possible implementation, the first polarization control module is configured to: splitting the first beam into two sub-beams; and carrying out phase modulation processing on the two sub-beams, so that the power difference value of the two sub-beams after the phase modulation processing is smaller than or equal to a reference value, and the two sub-beams after the phase modulation processing are respectively a first component and a second component.

In the solution shown in the present application, a phase modulation process can be used such that the power of the first and second components of the first light beam are close.

In one possible implementation, the first polarization control module includes a first PSR and a control unit; the first PSR is used for receiving a first light beam and dividing the first light beam into two sub-light beams; the control unit is used for carrying out phase modulation processing on the two sub-beams and outputting the two sub-beams subjected to phase modulation processing to the first receiving module; extracting feedback information from the phase-modulated at least one sub-beam; based on the feedback information, the phase modulation voltage for phase modulation processing is adjusted so that the power difference of the two sub-beams after the phase modulation processing is smaller than or equal to a reference value.

In the scheme shown in the application, the phase modulation voltage of the phase modulation processing is controlled by feeding back information so that the power of the first component and the power of the second component of the first light beam are close.

In one possible implementation manner, the control unit includes M phase modulation units, a feedback extraction unit and a first processing module, where N is greater than or equal to 1; the M phase modulation units are used for carrying out phase modulation processing on the two sub-beams output by the first PSR and outputting the two phase-modulated sub-beams to the first receiving module; the feedback extraction unit is used for extracting feedback information from at least one sub-beam after phase modulation processing; the first processing module is used for adjusting the phase modulation voltage of at least one phase modulation unit in the M phase modulation units based on the feedback information, so that the power difference value of the two sub-beams after phase modulation processing is smaller than or equal to a reference value.

In one possible implementation manner, the 1 st to the M th phase modulation units in the M phase modulation units are sequentially arranged along the local oscillation light transmission direction, and M is greater than 1; each phase modulation unit comprises a phase modulator and a 2 x 2 optical coupler; the input port and the output port of the phase modulator in the 1 st phase modulation unit are respectively connected with one output port of the first PSR and the first input port of the 2X 2 optical coupler in the 1 st phase modulation unit; a second input port of the 2 x 2 optical coupler in the 1 st phase modulation unit is connected with the other output port of the first PSR; two output ports of the 2X 2 optical coupler in the i-1 phase modulation unit are respectively connected with the input port of the phase modulator in the i phase modulation unit and the first input port of the 2X 2 optical coupler; the output port of the phase modulator in the i-1 phase modulation unit is connected with the second input port of the 2X 2 optical coupler, i is larger than 1 and smaller than or equal to M; two output ports of the 2X 2 optical coupler in the M phase modulation unit are respectively connected with the feedback extraction unit; the first processing module is configured to adjust a phase modulation voltage of a phase modulator in the at least one phase modulation unit based on the feedback information.

In the scheme shown in the application, the phase modulation unit is realized by a phase modulator and a 2×2 optical coupler, and the power of the first component and the power of the second component of the first light beam are close by adjusting the phase modulation voltage of the phase modulator.

In one possible implementation, the feedback extraction unit includes a first 1×2 splitter, a second 1×2 splitter, and a sub-extraction unit; the M phase modulation units are used for outputting two sub-beams subjected to phase modulation treatment to the first 1X 2 optical splitter and the second 1X 2 optical splitter respectively. The first 1×2 beam splitter is configured to split one beam after phase modulation into a first sub-beam and a second sub-beam, and output the first sub-beam and the second sub-beam to the first receiving module and the sub-extraction unit, respectively; the second 1×2 beam splitter is configured to split the other sub-beam after the phase modulation processing into a third sub-beam and a fourth sub-beam, and output the third sub-beam and the fourth sub-beam to the first receiving module and the sub-extraction unit, respectively; the sub-extraction unit is used for determining a first power, wherein the first power comprises a difference value of the power of the second sub-beam and the power of the fourth sub-beam, or comprises the power of the second sub-beam and the power of the fourth sub-beam; the first processing module is configured to adjust the phase modulation voltage of the at least one phase modulation unit based on a principle that a power difference between the second sub-beam and the fourth sub-beam is adjusted to be less than or equal to a reference value.

In the scheme shown in the application, for the first light beam, the power difference between the first component and the second component is determined to be minimum, so that the power of the first component and the power of the second component of the first light beam are close.

In one possible implementation, the feedback extraction unit includes a first 1×2 optical splitter and a sub-extraction unit; the M phase modulation units are used for outputting two sub-beams subjected to phase modulation processing to the first 1 multiplied by 2 beam splitter and the first receiving module respectively. The first 1×2 beam splitter is configured to split a sub-beam after phase modulation into a first sub-beam and a second sub-beam, and output the first sub-beam and the second sub-beam to the first receiving module and the sub-extraction unit, respectively; the sub-extraction unit is used for determining the power of the second sub-beam; the first processing module is used for adjusting the phase modulation voltage of the at least one phase modulation unit based on the principle that the power of the second sub-beam is adjusted to be a target value.

In the scheme shown in the application, the power of the second sub-beam is the target value, which means that the power of the second sub-beam is equal to the power of the first sub-beam, so that the power of the first component and the power of the second component of the first beam can be made to be close by controlling the power of the second sub-beam to be the target value.

In one possible implementation, the first receiving module includes a second PSR, a first coherent receiving unit, and a second processing module; the second PSR is used for dividing the first signal light into first sub-signal light and second sub-signal light; the first coherent receiving unit is configured to coherently receive the first sub-signal light by using a first component of the first beam to obtain a first result; and performing coherent reception on the second sub-signal light by using a second component of the first light beam to obtain a second result; the second processing module is configured to obtain data modulated on the first signal light based on the first result and the second result.

Thus, a receiving module for coherent reception is provided.

In one possible implementation, the second receiving module includes a sixth PSR, a second coherent receiving unit, and a sixth processing module; the sixth PSR is configured to divide the second signal light into a third sub-signal light and a fourth sub-signal light; the second coherent receiving unit is configured to coherently receive the third sub-signal light by using the first component of the second light beam, to obtain a third result; and performing coherent reception on the fourth sub-signal light by using the second component of the first light beam to obtain a fourth result; the sixth processing module is configured to obtain data modulated on the second signal light based on the third result and the fourth result. Thus, a receiving module for coherent reception is provided.

Drawings

Fig. 1 is a schematic structural diagram of a coherent transmitting apparatus according to an exemplary embodiment of the present application;

fig. 2 is a schematic structural diagram of a coherent transmitting apparatus according to an exemplary embodiment of the present application;

fig. 3 is a schematic structural diagram of a coherent transmitting apparatus according to an exemplary embodiment of the present application;

fig. 4 is a schematic diagram of a data receiving module according to an exemplary embodiment of the present application;

fig. 5 is a schematic structural diagram of a coherent receiving device according to an exemplary embodiment of the present application;

fig. 6 is a schematic structural diagram of a coherent receiving device according to an exemplary embodiment of the present application;

FIG. 7 is a schematic diagram of a polarization control module according to an exemplary embodiment of the present application;

FIG. 8 is a schematic diagram of a polarization control module according to an exemplary embodiment of the present application;

fig. 9 is a schematic structural diagram of a coherent receiving device according to an exemplary embodiment of the present application;

fig. 10 is a schematic structural diagram of a coherent receiving device according to an exemplary embodiment of the present application;

fig. 11 is a schematic structural diagram of a coherent receiving device according to an exemplary embodiment of the present application;

fig. 12 is a schematic diagram of a coherent communication device according to an exemplary embodiment of the present application;

Fig. 13 is a schematic structural diagram of a coherent communication system according to an exemplary embodiment of the present application;

fig. 14 is a schematic diagram of a coherent communication system according to an exemplary embodiment of the present application;

fig. 15 is a schematic structural diagram of a coherent communication device according to an exemplary embodiment of the present application;

fig. 16 is a schematic structural view of a first transmitting module according to an exemplary embodiment of the present application;

fig. 17 is a schematic structural diagram of a second transmitting module according to an exemplary embodiment of the present application;

FIG. 18 is a schematic diagram of a first polarization control module according to an exemplary embodiment of the present application;

FIG. 19 is a schematic diagram of a first polarization control module according to an exemplary embodiment of the present application;

FIG. 20 is a schematic diagram of a first polarization control module according to an exemplary embodiment of the present application;

fig. 21 is a schematic structural view of a first receiving module according to an exemplary embodiment of the present application;

FIG. 22 is a schematic diagram of a second polarization control module according to an exemplary embodiment of the present application;

fig. 23 is a schematic structural view of a second receiving module according to an exemplary embodiment of the present application;

fig. 24 is a schematic diagram of a coherent communication device according to an exemplary embodiment of the present application;

Fig. 25 is a schematic structural diagram of a coherent communication system according to an exemplary embodiment of the present application.

Description of the drawings

01. A light source; 02. a polarization changing module; 03. a data transmission module;

011. a first sub-light source; 1221. a first 1 x 2 beam splitter; 012. a second sub-light source; 1222. a second 1 x 2 beam splitter;

030. a processing module; 031. a first modulator; 032. a second modulator; 033. a first wave combining module; 034. the second wave combining module; 035. PSR;

1. a polarization control module; 2. a data receiving module; 11. a first PSR; 12. a control unit; 121. a phase modulation unit; 122. a feedback extraction unit; 123. a first processing module; 1211. a phase modulator; 1222. a 2 x 2 optocoupler;

21. a second PSR; 22. a first branching module; 23. a second wave splitting module; 24. a coherent receiving unit; 25. a second processing module;

241. a first sub-coherent receiving unit; 242. a second sub-coherent receiving unit;

10. a first transmitting module; 20. a second transmitting module; 30. a first connection module; 40. a second connection module; 50. a third connection module; 60. a fourth connection module; 70. a first polarization control module; 80. a second polarization control module; 90. a first receiving module; 100. a second receiving module;

0001. A target polarization control module; 0002. a first data receiving module;

101. a third processing module; 201. a fourth processing module; 202. a fourth PSR;

901. a first coherent receiving unit; 801. a fifth PSR; 802. a first control unit; 8021. a fifth processing module;

102. a second correlation receiving unit; 103. a sixth processing module; 1001. a sixth PSR1001;

001. a third polarization control module; 002. a fourth polarization control module; 003. a third receiving module; 004. and a fourth receiving module.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the embodiments of the present application will be described in further detail with reference to the accompanying drawings.

Some term concepts related to the embodiments of the present application are explained below.

(1) Coherent light refers to light having a defined frequency and phase. The coherent light may be, for example, laser light generated by a laser having spatially superimposed and mutually interfering properties.

(2) The coherent communication system is an optical fiber communication system, and may be called a coherent optical communication system or a coherent optical transmission system. The coherent communication system utilizes the phase, frequency, amplitude and other parameters of coherent light to bear more modulation information, so as to fully utilize the optical fiber bandwidth and realize ultra-high capacity data transmission.

(3) The homologous coherent communication system is characterized in that light emitted by a laser in a coherent transmitting device is divided into two paths, one path of light loads data to a modulator, signal light after the data loading is transmitted to a coherent receiving device through one path of light, and the other path of light is simultaneously transmitted to the coherent receiving device through the other optical fiber to serve as local oscillation light.

The current homologous coherent technology is applied to a 800G single-wavelength coherent communication system, but the bandwidth of an optoelectronic device is difficult to break through more than 130GB, and a 1.6T coherent communication system required in the future is easier to realize through a dual-wavelength 800G system.

In the embodiment of the application, the coherent receiving device and the coherent transmitting device can be applied to various network scenes. For example, the method can be applied to the scenes of backbone optical transmission network, optical access network, data center interconnection, short-distance optical interconnection, wireless service forward transmission or return transmission and the like.

For example, the coherent receiving apparatus may correspond to a receiving-side device of a different network or a system including the receiving-side device. The coherent transmitting apparatus may correspond to a transmitting-side device of a different network or a system including the transmitting-side device. A coherent communication system may correspond to communication devices of different networks.

The embodiment of the application is applied to a homologous dual-wavelength coherent communication system. The case of controlling the polarization states of two wavelengths using one polarization control module is described below. Specifically, the description is made in order of the coherent transmitting apparatus, the coherent receiving apparatus, the coherent communication device, and the coherent communication system.

(1) Coherent transmitter

Fig. 1 provides a schematic structural diagram of a coherent transmitter. Referring to fig. 1, the coherent transmission apparatus includes a light source 01, a polarization changing module 02, and a data transmission module 03. Wherein the light source 01 is capable of providing a first light beam, a second light beam, a third light beam and a fourth light beam, the first light beam and the third light beam having a wavelength of a first wavelength (lambda ₁ ) The wavelength of the second light beam and the fourth light beam is a second wavelength (lambda ₂ ). First light beam (lambda) _1LO ) And a second light beam (lambda) _2LO ) As local oscillation light, a third light beam (lambda _1s ) And a fourth light beam (lambda) _2s ) Used as data-carrying light. The light source 01 outputs the first light beam and the second light beam to the polarization changing module 02, and outputs the third light beam and the fourth light beam to the data transmitting module 03.

The polarization changing module 02 converts the polarization state of the first light beam into another polarization state, the other polarization state is orthogonal to the polarization state of the second light beam, the first light beam and the second light beam with the converted polarization states are combined into one beam, and the first local oscillation light is obtained and output to the coherent receiving device. Or the polarization changing module 02 converts the polarization state of the second light beam into a polarization state orthogonal to the polarization state of the first light beam, combines the second light beam with the converted polarization state and the first light beam into one beam, obtains the first local oscillation light, and outputs the first local oscillation light to the coherent receiving device. Optionally, the polarization state of the first light beam in the first local oscillation light is a transverse electric (transverse electric, TE) mode polarization state, the TE mode polarization state may be referred to as a TE mode polarization state or an X polarization state, and the polarization state of the second light beam is a transverse magnetic (transverse magnetic, TM) mode polarization state, and the TM mode polarization state may also be referred to as a TM polarization state or a Y polarization state.

The data transmitting module 03 receives the third light beam and the fourth light beam, modulates data onto the third light beam and the fourth light beam, and obtains first signal light including the third light beam modulated with data and the fourth light beam modulated with data. The data transmission module 03 outputs the first signal light to the coherent reception device.

The polarization changing module 02 may be a PSR, or may be another module capable of implementing polarization conversion, which is not limited by the embodiment of the present application.

In one implementation, FIG. 2 provides a schematic structural diagram of a light source. Referring to fig. 2, the light source 01 includes a first sub-light source 011, a first 1×2 beam splitter 1221, a second sub-light source 012, and a second 1×2 beam splitter 1222.

The first sub-light source 011 may be a first wavelength laser for providing light of a first wavelength, and the first sub-light source 011 outputs light of the first wavelength to the first 1×2 beam splitter 1221. The first 1×2 beam splitter 1221 splits the light of the first wavelength into two beams, which are the first beam and the third beam, respectively, and the power of the first beam and the power of the third beam may be equal or unequal. The first 1×2 beam splitter 1221 outputs the first light beam to the polarization changing module 02, and outputs the third light beam to the modulator in the data transmitting module 03.

The second sub light source 012 may be a laser of a second wavelength for providing light of the second wavelength, and the second sub light source 012 outputs light of the second wavelength to the second 1×2 beam splitter 1222. The second 1×2 beam splitter 1222 splits the light of the second wavelength into two beams, which are respectively the second beam and the fourth beam, and the power of the second beam and the fourth beam may be equal or unequal. The second 1×2 beam splitter 1222 outputs a second light beam to the polarization changing module 02, and outputs a fourth light beam to the modulator of the data transmitting module 03.

In one implementation, fig. 3 provides a schematic structural diagram of a coherent transmitting apparatus. Referring to fig. 3, the data transmitting module 03 includes a processing module 030, a first modulator 031, a second modulator 032, a first combining module 033, a second combining module 034, and a PSR035.

The processing module 030 transmits data to the first modulator 031 and the second modulator 032, respectively, and the data transmitted respectively may be different data or the same data. The first modulator 031 receives the third beam, divides the third beam into a first sub-beam and a second sub-beam, and modulates data onto the first sub-beam and the second sub-beam, where the data modulated on the first sub-beam and the second sub-beam may be the same or different. The first modulator 031 outputs the first sub-beam modulated with data to the first combining module 033 and outputs the second sub-beam modulated with data to the second combining module 034. Here, the power of the first sub-beam and the second sub-beam may be equal or unequal.

The second modulator 032 receives the fourth light beam, divides the fourth light beam into a third sub-beam and a fourth sub-beam, and modulates data onto the third sub-beam and the fourth sub-beam, respectively, where the modulated data on the third sub-beam and the fourth sub-beam may be the same or different. The second modulator 032 outputs the third sub-beam modulated with data to the first multiplexing module 033, and outputs the fourth sub-beam modulated with data to the second multiplexing module 034. Here, the powers of the third sub-beam and the fourth sub-beam may be equal or unequal.

The first combining module 033 combines the first sub-beam modulated with data and the third sub-beam modulated with data into one beam to obtain a first sub-signal light, and outputs the first sub-signal light to the PSR 035. The second combining module 034 combines the third sub-beam modulated with data and the fourth sub-beam modulated with data into one beam to obtain a second sub-signal light, and outputs the second sub-signal light to the PSR 035.

The PSR035 rotates the polarization state of the first sub-signal light to be orthogonal to the polarization state of the second sub-signal light, and combines the first sub-signal light and the second sub-signal light after the polarization state is adjusted to be one beam to obtain the first signal light. In this way, the first sub-beam modulated with data is orthogonal to the polarization state of the second sub-beam modulated with data, the third sub-beam modulated with data is orthogonal to the polarization state of the fourth sub-beam modulated with data, and data in two polarization states can be transmitted in the optical fiber, so that the utilization rate of the optical transmission channel is higher.

Alternatively, fig. 4 provides a schematic structural diagram of the data transmission module 03. Referring to fig. 4, the processing module 030 includes a first digital signal processor (digital signal process, DSP), a digital-to-analog converter (digital analog converter, DAC) and a driver circuit. The first DSP is used to provide a digital signal of data for transmission to the DAC. The DAC is used for converting the digital signal into an analog signal and transmitting the analog signal to the driving circuit. The driving circuit is used for converting the analog signal into an electrical signal and transmitting the electrical signal to the first modulator 031 and the second modulator 032.

Optionally, the first modulator 031, the second modulator 032, the first wave combining module 033, the second wave combining module 034 and the PSR035 may be implemented by a silicon optical chip, and since the silicon optical chip can transmit light in a TE mode polarization mode, the first sub-signal light and the second sub-signal light are both in the TE mode polarization mode before being output from the PSR035, the polarization state of the first sub-signal light is rotated to the TM mode polarization mode after passing through the PSR035, and the polarization state of the second sub-signal light is also in the TE mode polarization mode after passing through the PSR 035.

(2) Coherent receiving device

Fig. 5 provides a schematic structural diagram of a coherent receiver. Referring to fig. 5, the coherent receiving apparatus includes a polarization control module 1 and a data receiving module 2. An optical communication connection is established between the polarization control module 1 and the data receiving module 2, for example, a part of structures in the data receiving module 2 and the polarization control module 1 are realized through a silicon optical chip, and the polarization control module 1 and the data receiving module 2 are in communication connection through an optical waveguide.

The polarization control module 1 receives first local oscillation light sent by the coherent sending device, wherein the first local oscillation light comprises a first light beam and a second light beam with polarization states orthogonal to each other. The polarization control module 1 can control the polarization state of the first local oscillation light, and separate the first local oscillation light into a first light beam and a second light beam by controlling the polarization state of the first local oscillation light. The polarization control module 1 outputs a first light beam and a second light beam to the data receiving module 2.

The data receiving module 2 receives the first signal light transmitted by the coherent transmitting apparatus, the first signal light including the third light beam modulated with data and the fourth light beam modulated with data. The third light beam has the same wavelength as the first light beam and the first light beam, and the fourth light beam has the same wavelength as the second light beam and the second light beam.

The data receiving module 2 separates the first signal light into a third light beam modulated with data and a fourth light beam modulated with data. The data receiving module 2 acquires data modulated on the third beam using the first beam and acquires data modulated on the fourth beam using the second beam.

Thus, since the local oscillation light of two wavelengths can be separated by using only one polarization control module 1, not only can the coherent communication of two wavelengths be realized, but also the volume of the coherent receiving apparatus can be made smaller.

In addition, the polarization states of the first light beam and the second light beam may change during the process of transmitting the first light beam from the coherent transmitting device to the coherent receiving device, so that the first local oscillation light beam received by the coherent receiving device may not be TE mode polarization mode or TM mode polarization mode, although the polarization states of the first light beam and the second light beam are orthogonal.

In one implementation, the polarization control module 1 may divide the first local oscillation light into two beams, and perform phase modulation processing on the two beams, so that the two beams after the phase modulation processing are the first beam and the second beam, and separation of the local oscillation light with two wavelengths is achieved.

In another implementation, the polarization control module 1 changes the local oscillation light of two wavelengths in the first local oscillation light into a TE mode polarization mode and a TM mode polarization mode, and then separates the local oscillation light of two wavelengths by using one polarization beam splitter.

In one implementation, in case of separating the first and second light beams by a phase modulation process, the polarization control module 1 includes a first PSR11 and a control unit 12, see fig. 6. The first PSR11 receives the first local oscillation light and divides the first local oscillation light into two light beams. The control unit 12 performs phase modulation processing on the two light beams, that is, adjusts the phases of the two light beams, extracts feedback information, which may be optical power or the like, from at least one of the light beams after the phase modulation processing, and outputs the two light beams after the phase modulation processing to the data receiving module 2. The control unit 12 adjusts the phase modulation voltage to be subjected to the phase modulation processing using the feedback information, and makes the two light beams after the phase modulation processing be the first light beam and the second light beam, respectively, by the adjusted phase modulation voltage. The phase modulation voltage is a voltage for adjusting the phase.

Optionally, the first PSR11 is implemented by a silicon optical chip, and the polarization states of the first local oscillation light divided into two light beams are TE mode polarization states.

Alternatively, fig. 7 provides a schematic structural diagram of the polarization control module 1, referring to fig. 7, the control unit 12 includes N phase modulation units 121, a feedback extraction unit 122, and a first processing module 123, where N is greater than or equal to 1. For example, N takes a value of 3. The N phase modulation units 121 perform phase modulation processing on the two light beams output from the first PSR11, and output the phase-modulated two light beams to the data receiving module 2. The feedback extraction unit 122 extracts feedback information from the phase-modulated at least one light beam. The first processing module 123 uses the feedback information to determine a phase modulation voltage of at least one phase modulation unit 121, and uses the adjusted phase modulation voltage to control the phase modulation unit 121 so that the phase-modulated two light beams are a first light beam and a second light beam, respectively.

Alternatively, the control unit 12 includes a first 2×2 optocoupler, N phase modulation units 121, a feedback extraction unit 122, and a first processing module 123, N being greater than or equal to 1. The first 2×2 optical coupler is configured to receive the two light beams output by the first PSR11, adjust a rotation angle of polarization states of the two light beams, and output the two light beams. The N phase modulation units 121 perform phase modulation processing on the two light beams output from the first 2×2 optical coupler, and output the phase-modulated two light beams to the data receiving module 2. The feedback extraction unit 122 extracts feedback information from the phase-modulated at least one light beam. The first processing module 123 adjusts the phase modulation voltage of at least one phase modulation unit 121 of the N phase modulation units 121 based on the feedback information, so that the two phase-modulated light beams are the first light beam and the second light beam respectively.

Where N takes a value of 1, phase modulation unit 121 includes phase modulator 1211 and 2 x 2 optocoupler 1212. The phase modulator 1211 is used to change the phase of the input beam. The 2×2 optical coupler 1212 is used to couple and split the two input light beams into two light beams. The 2 x 2 optical coupler 1212 may be a multimode interference coupler (multi-mode interference coupler, MMI).

The input port of the phase modulator 1211 is connected to a first output port of the first PSR11, which is a port outputting one light beam, and the output port of the phase modulator 1211 is connected to a first input port of the 2×2 optical coupler 1212. The second output port of the first PSR11 is connected to the second input port of the 2×2 optical coupler 1212, which is a port outputting another optical beam. Two output ports of the 2×2 optocoupler 1212 are connected to the feedback extraction unit 122, or one output port is connected to the feedback extraction unit 122 and the other is connected to the data reception module 2.

When the value of N is greater than 1, the 1 st to nth phase modulation units 121 of the N phase modulation units 121 are sequentially arranged along the local oscillation optical transmission direction. Fig. 8 provides a schematic diagram of a structure of the polarization control module 1, referring to fig. 8, in the polarization control module 1, an input port of a phase modulator 1211 in the 1 st phase modulation unit 121 is connected to a first output port of the first PSR11, and an output port of the phase modulator 1211 is connected to a first input port of a 2×2 optical coupler 1212 in the 1 st phase modulation unit 121. A second input port of the 2 x 2 optocoupler 1212 is connected to a second output port of the first PSR 11.

Two output ports of the 2×2 optical coupler 1212 in the i-1 st phase modulation unit 121 are connected to the input port of the phase modulator 1211 in the i-1 st phase modulation unit 121 and the first input port of the 2×2 optical coupler 1212, respectively. The output port of phase modulator 1211 in the i-1 st phase modulation unit 121 is connected to the second input port of 2 x 2 optocoupler 1212. Wherein i is greater than 1 and less than or equal to N.

The nth phase modulation unit 121 is the last phase modulation unit 121, and two output ports of the 2×2 optocoupler 1212 in the nth phase modulation unit 121 are connected to the feedback extraction unit 122. Alternatively, two output ports of the 2×2 optical coupler 1212 in the nth phase modulation unit 121 are connected to the feedback extraction unit 122 and the data receiving module 2, respectively. The feedback extraction unit 122 extracts the feedback information and supplies the feedback information to the first processing module 123. The first processing module 123 adjusts the phase modulation voltage of the phase modulator 1211 in the at least one phase modulation unit 121 based on the feedback information.

The above-mentioned only one possible structure of the phase modulation unit 121, and any device or module structure capable of implementing the phase modulation function can be applied to the embodiment of the present application, which is not limited thereto. For example, in the polarization control module 1 shown in fig. 7, the phase modulator 1211 is used to adjust the phase of one beam, and in another implementation the phase modulator 1211 can be used to adjust the phase of both beams.

Alternatively, referring to fig. 8, the feedback extraction unit 122 includes a first 1×2 beam splitter 1221, a second 1×2 beam splitter 1222, and a sub extraction unit 1223. The plurality of phase modulation units 121 output phase-modulated two light beams, one of which is output to the first 1×2 beam splitter 1221 and the other of which is output to the second 1×2 beam splitter 1222. The first 1×2 beam splitter 1221 splits a received one beam into a first sub-beam and a second sub-beam, and outputs the first sub-beam and the second sub-beam to the data receiving module 2 and the sub-extraction unit 1223, respectively. The second 1×2 beam splitter 1222 splits a received sub-beam into a third sub-beam and a fourth sub-beam, and outputs the third sub-beam and the fourth sub-beam to the data receiving module 2 and the sub-extraction unit 1223, respectively. Wherein the power of the first sub-beam is greater than the power of the second sub-beam and the power of the third sub-beam is greater than the power of the fourth sub-beam.

The sub-extraction unit 1223 filters out light of the first wavelength so that only light of the second wavelength is extracted when the second sub-beam is received, and filters out light of the second wavelength so that only light of the first wavelength is extracted when the fourth sub-beam is received. The sub-extraction unit 1223 detects the power of the light of the second wavelength in the second sub-beam and detects the power of the light of the first wavelength in the fourth sub-beam, determines the sum of the two powers as a target power, outputs the target power to the first processing module 123, or the sub-extraction unit 1223 outputs the power of the light of the second wavelength in the second sub-beam and the power of the light of the first wavelength in the fourth sub-beam to the first processing module 123, the target power including the two powers. The target power may be the power of the light of the second wavelength in the second sub-beam or the power of the light of the first wavelength in the fourth sub-beam.

The first processing module 123 adjusts the phase modulation voltage of the at least one phase modulation unit 121 according to the principle of adjusting the target power to a minimum value. For example, the first processing module 123 may adjust the phasing voltage by a preset step size. Here, when the target power includes the power of the light of the second wavelength in the second sub-beam and the power of the light of the first wavelength in the fourth sub-beam, the target power minimum means that both of the powers are minimum.

Thus, when the second sub-beam includes less light of the second wavelength and the fourth sub-beam includes less light of the first wavelength, the local oscillation light separation of the two wavelengths is completed.

Alternatively, fig. 9 provides another structural schematic diagram of the polarization control module 1. Referring to fig. 9, the feedback extraction unit 122 includes a first 1×2 beam splitter 1221 and a sub extraction unit 1223. The plurality of phase modulation units 121 output two beams after phase modulation processing, one beam is output to the first 1×2 beam splitter 1221, and the other beam is output to the data receiving module 2. The first 1×2 beam splitter 1221 splits a received one beam into a first sub-beam and a second sub-beam, and outputs the first sub-beam and the second sub-beam to the data receiving module 2 and the sub-extraction unit 1223, respectively. Wherein the power of the first sub-beam is greater than the power of the second sub-beam.

The sub-extraction unit 1223 filters out light of the first wavelength while receiving the second sub-beam, so that only light of the second wavelength is extracted. The sub-extraction unit 1223 detects the power of the light of the second wavelength in the second sub-beam, and outputs the power to the first processing module 123. The first processing module 123 adjusts the phase modulation voltage of at least one phase modulation unit 121 on the basis of adjusting the power to a minimum value.

Thus, when the second sub-beam includes less light of the second wavelength in one beam, it means that the light of the first wavelength in the other beam is also less, and the local oscillation light separation of the two wavelengths is completed. In addition, the feedback providing unit 122 may also include a second 1×2 optical splitter 1222 and a sub-extraction unit 1223, and description of extracting feedback information is referred to in fig. 8 and 9, and will not be repeated here.

Optionally, the sub-extraction unit 1223 includes a photodetector and an analog-to-digital converter (analog digital converter, ADC), the photodetector detecting the target power, the ADC converting the target power into an analog signal, the ADC sending the analog signal to the first processing module 123. The first processing module 123 determines the phasing voltage indication information, which may be transmitted in the form of an analog signal, and transmits the phasing voltage indication information to the at least one phasing unit 121.

Alternatively, the first processing module 123 may be a field programmable gate array (field programmable gate array, FPGA) or an application-specific integrated circuit (ASCI), or the like.

Illustratively, the polarization state of the third beam modulated with data is orthogonal, and the polarization state of the fourth beam modulated with data is orthogonal, in which case fig. 10 provides a schematic diagram of the structure of the coherent receiving device. Referring to fig. 10, the data receiving module 2 includes a second PSR21, a first demultiplexing module 22, a second demultiplexing module 23, a coherent receiving unit 24, and a second processing module 25.

The second PSR21 receives the first signal light, separates the first signal light into a first sub-signal light including a third light beam modulated with data and a fourth light beam modulated with data, and a second sub-signal light including the third light beam modulated with data and the fourth light beam modulated with data. The first sub-signal light and the second sub-signal light are transmitted to the first and second branching modules 22 and 23, respectively.

The first demultiplexing module 22 separates the signal light of the first wavelength from the signal light of the second wavelength in the first sub-signal light, and outputs the signal light of the first wavelength and the signal light of the second wavelength to the coherent receiving unit 24. The second wave splitting module 23 splits the signal light of the first wavelength from the signal light of the second wavelength in the second sub-signal light, and outputs the signal light of the first wavelength and the signal light of the second wavelength to the coherent receiving unit 24.

The coherent receiving unit 24 performs coherent reception of light of a first wavelength using a first light beam to obtain a first result, and performs coherent reception of light of a second wavelength using a second light beam to obtain a second result. The coherent receiving unit 24 outputs the first result and the second result to the second processing module 25.

The second processing module 25 uses the first and second results to obtain data modulated on the third and fourth beams.

Alternatively, referring to the coherent receiving apparatus shown in fig. 11, the coherent receiving unit 24 includes a first sub-coherent receiving unit 241 and a second sub-coherent receiving unit 242. The first sub-coherent receiving unit 241 includes a first optical splitter, two mixers, and a first photoelectric conversion module. The first beam splitter splits the first beam into two beams, one beam is used for mixing with the signal light with the first wavelength output by the first beam splitter module 22 in one mixer, outputting the optical signal after the mixing, and the other beam is used for mixing with the signal light with the first wavelength output by the second beam splitter module 23 in the other mixer, and outputting the optical signal after the mixing. The first photoelectric conversion module converts the optical signal after the mixing process into an electrical signal to obtain a first result, and outputs the first result to the second processing module 25. The second sub-coherent receiving unit 242 includes a second optical splitter, two mixers, and a second photoelectric conversion module. The second beam splitter splits the second light beam into two beams, one beam is used for mixing with the signal light with the second wavelength output by the first beam splitter module 22 in one mixer, outputting the optical signal after the mixing, the other beam is used for mixing with the signal light with the second wavelength output by the second beam splitter module 23 in the other mixer, outputting the optical signal after the mixing, and the second photoelectric conversion module converts the optical signal after the mixing into an electrical signal to obtain a second result and outputs the second result to the second processing module 25.

The signal light of the first wavelength output by the first demultiplexing module 22 and the signal light of the first wavelength output by the second demultiplexing module 23 are two paths of signal light output by the first modulator 031, and the two paths of signal light are a first path of sub-beam modulated with data and a second path of sub-beam modulated with data. The signal light of the second wavelength output by the first branching module 22 and the signal light of the second wavelength output by the second branching module 23 are two paths of signal light output by the second modulator 032, and the two paths of signal light are a third path of sub-beam modulated with data and a fourth path of sub-beam modulated with data.

Optionally, referring to the data receiving module 2 shown in fig. 11, the second processing module 25 includes a trans-impedance amplifier (TIA-impedance amplifier), an ADC, and a second DSP. The TIA amplifies the electrical signal. The ADC converts the amplified electrical signal into a digital signal. The second DSP obtains data modulated on the third light beam and the fourth light beam from the digital signal.

When the second PSR21, the first branching module 22, the second branching module 23, and the coherent receiving unit 24 are implemented by a silicon optical chip, the second PSR21 converts the signal light of the TM mode polarization mode transmitted by the coherent transmitting apparatus into the signal light of the TE mode polarization mode, so that the first signal light can be transmitted inside the silicon optical chip. Similarly, when the polarization control module 1 is implemented by a silicon optical chip, the first PSR11 converts the local oscillation light of the TM mode polarization mode sent by the coherent sending device into the local oscillation light of the TE mode polarization mode, so that the local oscillation light can be transmitted inside the silicon optical chip.

The reason why the first PSR11 and the control unit 12 can separate the local oscillation light of the first wavelength from the local oscillation light of the second wavelength is that: when the local oscillation light of the first wavelength and the local oscillation light of the second wavelength are transmitted in the optical fiber, the phase angle and the rotation angle are changed, and the phase modulator 1211 and the 2×2 optical coupler 1212 are matched with each other to change the phase angle and the rotation angle, so that the phase angle and the rotation angle of the local oscillation light of the first wavelength can be recovered by the phase modulator 1211 and the 2×2 optical coupler 1212, and the phase angle and the rotation angle of the local oscillation light of the second wavelength can be recovered, and thus the local oscillation light of the first wavelength and the local oscillation light of the second wavelength can be separated.

(3) Coherent communication device

The coherent communication device comprises the coherent receiving means described in the foregoing, which means that the coherent communication device is only provided with a coherent receiving function. Or the coherent communication device comprises the coherent transmission means described in the foregoing, which means that the coherent communication device is only provided with a coherent transmission function. Alternatively, the coherent communication device may transmit data to another coherent communication device using light of the first wavelength and the second wavelength, and may receive data transmitted by another communication device using light of the third wavelength and the fourth wavelength, and the coherent communication device may have both a coherent transmission function and a coherent reception function.

Fig. 12 provides a schematic diagram of a configuration of a coherent communication device. Referring to fig. 12, the coherent communication apparatus includes a coherent receiving device, a coherent transmitting device, a connection module a for connecting an external communication optical fiber, and a connection module B for connecting an external communication optical fiber.

The coherent transmitting apparatus includes a light source 01, a polarization changing module 02, and a data transmitting module 03, and the coherent receiving apparatus includes a target polarization control module 0001 and a first data receiving module 0002. The connection module a is connected to the polarization changing module 02 and the first data receiving module 0002, respectively, and the connection module B is connected to the data transmitting module 03 and the target polarization control module 0001, respectively.

The light source 01 is configured to output a first light beam, a second light beam, a third light beam, and a fourth light beam, the first light beam and the second light beam serving as local oscillation light, and the third light beam and the fourth light beam serving as signal light. The first and third light beams have a first wavelength and the second and fourth light beams have a second wavelength. The light source 01 outputs the first light beam and the second light beam to the polarization changing module 02, and outputs the third light beam and the fourth light beam to the data transmitting module 03.

The polarization changing module 02 combines the first light beam and the second light beam into a first local oscillation light beam with orthogonal polarization states, and outputs the first local oscillation light beam to the connecting module a. The connection module A outputs the first local oscillation light to another coherent receiving device.

The data transmitting module 03 receives the third light beam and the fourth light beam, modulates data onto the third light beam and the fourth light beam, and obtains first signal light including the third light beam modulated with data and the fourth light beam modulated with data. The data transmission module 03 outputs the first signal light to the connection module B. The connection module B outputs the first signal light to another coherent communication device.

The connection module B receives the local oscillation light a sent by another coherent communication device, and outputs the local oscillation light a to the target polarization control module 0001, where the local oscillation light a includes a fifth light beam (λ) having polarization states orthogonal to each other _3LO ) And a sixth light beam (lambda) _4LO ) The fifth light beam and the sixth light beam serve as local oscillation light. The target polarization control module 0001 can control the polarization state of the local oscillation light A, and the polarization state of the local oscillation light A is controlled to beThe local oscillation light A is separated into a fifth light beam and a sixth light beam. The target polarization control module 0001 outputs the fifth light beam and the sixth light beam to the first data receiving module 0002.

The connection module a receives a second signal light transmitted from another coherent communication device, outputs the second signal light to the first data receiving module 0002, the second signal light including a seventh light beam (λ) modulated with data _3s ) And an eighth light beam (lambda) modulated with data _4s ) The wavelength of the seventh light beam and the fifth light beam is a third wavelength (lambda ₃ ) The eighth and sixth light beams have a wavelength of fourth wavelength (lambda ₄ ). The first data receiving module 0002 separates the second signal light into a seventh light beam modulated with data and an eighth light beam modulated with data. The first data receiving module 0002 acquires data modulated on the seventh light beam using the fifth light beam, and acquires data modulated on the eighth light beam using the sixth light beam.

In this way, the coherent transmitting means in the coherent communication device transmits data to the other coherent communication device using light of the first wavelength and the second wavelength, and receives data transmitted by the other coherent communication device using light of the third wavelength and the fourth wavelength, which are not equal.

Optionally, polarization states of the first light beam and the second light beam in the first local oscillation light are orthogonal to each other. The polarization state of the third light beam modulated with data in the first signal light is an orthogonal polarization state, and the polarization state of the fourth light beam modulated with data is an orthogonal polarization state.

Optionally, polarization states of the fifth beam and the sixth beam in the local oscillation light a are orthogonal to each other. The polarization state of the seventh light beam modulated with data in the second signal light is an orthogonal polarization state, and the polarization state of the eighth light beam modulated with data is an orthogonal polarization state.

The specific structures of the coherent receiving apparatus and the coherent transmitting apparatus are described in the foregoing, and are not repeated here.

(4) Coherent communication system

Fig. 13 provides a schematic structural diagram of a coherent communication system. Referring to fig. 13, the coherent communication system includes the coherent transmitting apparatus described in the foregoing and the coherent receiving apparatus described in the foregoing, which are connected by the first optical fiber and the second optical fiber.

As described above, the coherent transmission apparatus includes the light source 01, the polarization changing module 02, and the data transmission module 03. The coherent receiving module comprises a polarization control module 1 and a data receiving module 2.

The light source 01 is used for outputting a first light beam, a second light beam, a third light beam and a fourth light beam, wherein the first light beam and the second light beam are used as local oscillation light, and the third light beam and the fourth light beam are used as light for bearing data. The first and third light beams have a first wavelength and the second and fourth light beams have a second wavelength. The light source 01 outputs the first light beam and the second light beam to the polarization changing module 02, and outputs the third light beam and the fourth light beam to the data transmitting module 03.

The polarization changing module 02 combines the first light beam and the second light beam into a first local oscillation light beam with orthogonal polarization states, and outputs the first local oscillation light beam to the coherent receiving device through the connected first optical fiber.

The data transmitting module 03 receives the third light beam and the fourth light beam, modulates data onto the third light beam and the fourth light beam, and obtains first signal light including the third light beam modulated with data and the fourth light beam modulated with data. The data transmission module 03 outputs the first signal light to the coherent receiving device through the connected second optical fiber.

As in the previous description, the coherent receiving device includes a polarization control module 1 and a data receiving module 2. An optical communication connection is established between the polarization control module 1 and the data receiving module 2. The polarization control module 1 receives first local oscillation light output by the coherent transmitting device, wherein the first local oscillation light comprises a first light beam and a second light beam with orthogonal polarization states. The polarization control module 1 can control the polarization state of the first local oscillation light, and separate the first local oscillation light into a first light beam and a second light beam by controlling the polarization state of the first local oscillation light. The polarization control module 1 outputs a first light beam and a second light beam to the data receiving module 2.

The data receiving module 2 receives the first signal light output from the coherent transmitting apparatus, the first signal light including the third light beam modulated with data and the fourth light beam modulated with data. The data receiving module 2 separates the first signal light into a third light beam modulated with data and a fourth light beam modulated with data. The data receiving module 2 acquires data modulated on the third beam using the first beam and acquires data modulated on the fourth beam using the second beam.

For the details of the coherent receiving apparatus and the coherent transmitting apparatus in the coherent communication system, reference is made to the foregoing description, and no further description is given here.

Fig. 14 provides another structural schematic diagram of a coherent communication system. Referring to fig. 14, the coherent communication system includes a coherent communication device (referred to as a coherent communication device a) shown in fig. 12 and another coherent communication device (referred to as a coherent communication device B). The structure of the coherent communication device B is similar to that of the coherent communication device a, and will not be described here again.

The coherent communication device a corresponds to the coherent communication device B, i.e., the coherent communication device B transmits data to the coherent communication device a using light of the third wavelength and the fourth wavelength, and receives data transmitted by the coherent communication device a using light of the first wavelength and the second wavelength.

The case of controlling the polarization state of one wavelength using one polarization control module is described below. Specifically, the description is made in order of a coherent communication system and a coherent communication apparatus.

(1) Coherent communication system

Fig. 15 provides a schematic structural diagram of a coherent communication system. Referring to fig. 15, the coherent communication system includes a coherent transmitting device and a coherent receiving device connected by an optical fiber. The coherent transmission apparatus includes a light source 01, a first transmission module 10, a second transmission module 20, a first connection module 30, and a second connection module 40. The coherent receiving device includes a third connection module 50, a fourth connection module 60, a first polarization control module 70, a second polarization control module 80, a first receiving module 90, and a second receiving module 100.

The light source 01 is used for outputting a first light beam, a second light beam, a third light beam and a fourth light beam, wherein the first light beam and the second light beam are used as local oscillation light, and the third light beam and the fourth light beam are used as light for bearing data. The first and third light beams have a first wavelength and the second and fourth light beams have a second wavelength. The light source 01 outputs a first light beam and a second light beam to the first connection module 30, respectively. And the light source 01 outputs a third light beam to the first transmitting module 10 and a fourth light beam to the second transmitting module 20.

The first connection module 30 outputs a first light beam and a second light beam, respectively. The first light beam and the second light beam are output through one external optical fiber connected by the first connection module 30.

The first transmitting module 10 modulates data onto the third light beam to obtain the first signal light, and outputs the first signal light to the second connecting module 40. The second transmitting module 20 modulates data onto the fourth light beam to obtain second signal light, and outputs the second signal light to the second connecting module 40.

The second connection module 40 outputs the first signal light and the second signal light, respectively. The first signal light and the second signal light are output through one external optical fiber connected by the second connection module 40.

The third connection module 50 receives the first and second light beams, outputs the first light beam to the first polarization control module 70, and outputs the second light beam to the second polarization control module 80.

The first polarization control module 70 divides the first light beam into a first component and a second component, and controls the power difference between the first component and the second component to be less than or equal to a reference value, which is relatively small. For example, the power difference between the first component and the second component is 0. The fourth connection module 60 receives the first signal light and outputs the first signal light to the first reception module 90. The first receiving module 90 divides the first signal light into two sub-signal lights, and acquires data modulated on the two sub-signal lights using the first component and the second component of the first light beam, respectively.

The second polarization control module 80 divides the second light beam into a first component and a second component, and controls the power difference between the first component and the second component to be less than or equal to a reference value, which is relatively small. For example, the power difference between the first component and the second component is 0. The fourth connection module 60 receives the second signal light and outputs the second signal light to the second reception module 100. The second receiving module 100 divides the second signal light into two sub-signal lights, and acquires data modulated on the two sub-signal lights using the first component and the second component of the second light beam, respectively.

Thus, for the polarization states of the two wavelengths, the two polarization control modules are used for controlling respectively, and the power difference between the first component and the second component is smaller, so that the two sub-signal lights in the first signal light can be received, and the two sub-signal lights of the second signal light can be received.

Exemplary, fig. 16 provides a schematic structural diagram of the first transmitting module 10. Referring to fig. 16, the first transmitting module 10 includes a third processing module 101, a first modulator 031 and a PSR035. The third processing module 101 sends data to the first modulator 031. The first modulator 031 receives the third beam, divides the third beam into a first sub-beam and a second sub-beam, and modulates data onto the first sub-beam and the second sub-beam, respectively. The first modulator 031 outputs the first sub-beam modulated with data and the second sub-beam modulated with data to the PSR035. Here, the power of the first sub-beam and the second sub-beam may be equal or unequal.

The PSR035 rotates the polarization state of the first sub-beam modulated with data into a first polarization state which is orthogonal to the polarization state of the second sub-beam modulated with data, and combines the first sub-beam modulated with data and the second sub-beam modulated with data after the polarization state is adjusted into one beam to obtain the first local oscillation light. In this way, the first sub-beam modulated with data is orthogonal to the polarization state of the second sub-beam modulated with data, and data in two polarization states can be transmitted in the optical fiber, so that the utilization rate of the optical transmission channel is relatively high.

Optionally, the third processing module 101 includes a first DSP, DAC and driving circuitry. The first DSP provides a digital signal of data that is transferred to the DAC. The DAC is used for converting the digital signal into an analog signal and transmitting the analog signal to the driving circuit. The driving circuit is used for converting the analog signal into an electrical signal and transmitting the electrical signal to the first modulator 031.

Fig. 17 provides a schematic structural diagram of the second transmitting module 20. Referring to fig. 17, the second transmitting module 20 includes a fourth processing module 201, a second modulator 032, and a fourth PSR202. The fourth processing module 201 sends data to the second modulator 032. The second modulator 032 receives the fourth light beam, divides the fourth light beam into a third sub-beam and a fourth sub-beam, and modulates data onto the third sub-beam and the fourth sub-beam, respectively. The second modulator 032 outputs the third sub-beam modulated with data and the fourth sub-beam modulated with data to the fourth PSR202. Here, the power of the third sub-beam and the fourth sub-beam may be equal or unequal.

The fourth PSR202 rotates the polarization state of the third sub-beam modulated with data to the first polarization state, the polarization state of the fourth sub-beam modulated with data in the first polarization state is orthogonal, and combines the third sub-beam modulated with data and the fourth sub-beam modulated with data after the polarization state adjustment into one beam, thereby obtaining the second signal light. In this way, the third sub-beam modulated with data is orthogonal to the polarization state of the fourth sub-beam modulated with data, and data in two polarization states can be transmitted in the optical fiber, so that the utilization rate of the optical transmission channel is relatively high.

Here, the first polarization state may be a TM mode polarization mode, and the polarization state orthogonal to the first polarization state is a TE mode polarization mode.

Optionally, the fourth processing module 201 includes a second DSP, DAC and driving circuitry. The second DSP provides a digital signal of the data to the DAC. The DAC is used for converting the digital signal into an analog signal and transmitting the analog signal to the driving circuit. The driving circuit is used for converting the analog signal into an electric signal and transmitting the electric signal to the second modulator 032.

The polarization states of the third light beam modulated with data in the first signal light are orthogonal, the first component of the first light beam is used for receiving data of one polarization state of the third light beam modulated with data, namely, data modulated on the first sub-light beam, and the second component is used for receiving data of the other polarization state of the third light beam modulated with data, namely, data modulated on the second sub-light beam. The polarization states of the fourth light beam modulated with data in the second signal light are orthogonal, the first component of the second light beam is used for receiving the data of one polarization state of the fourth light beam modulated with data, namely the data modulated on the third sub-light beam, and the second component is used for receiving the data of the other polarization state of the fourth light beam modulated with data, namely the data modulated on the fourth sub-light beam.

Illustratively, after the first polarization control module 70 receives the first light beam, the first light beam is split into two sub-light beams, and the two sub-light beams are subjected to phase modulation processing, so that the power difference of the two sub-light beams after the phase modulation processing is less than or equal to the reference value.

Alternatively, fig. 18 provides a schematic structural diagram of the first polarization control module 70. Referring to fig. 18, the first polarization control module 70 includes a first PSR11 and a control unit 12, the first PSR11 receiving a first light beam and dividing the first light beam into two sub-light beams. The control unit 12 performs phase modulation processing on the two sub-beams, that is, adjusts phases of the two sub-beams, extracts feedback information, which may be optical power or the like, from at least one of the sub-beams after the phase modulation processing, and outputs the two sub-beams after the phase modulation processing to the first receiving module 90. The control unit 12 adjusts the phase modulation voltage subjected to the phase modulation processing using the feedback information, and controls the power difference between the two sub-beams subjected to the phase modulation processing to be less than or equal to the reference value by the adjusted phase modulation voltage.

Optionally, control unit 12 includes M phase modulation units 121, feedback extraction unit 122, and first processing module 123, M being greater than or equal to 1. For example, M has a value of 2. The M phase modulation units 121 perform phase modulation processing on the two sub-beams output from the first PSR11, and output the phase-modulated two sub-beams to the first receiving module 90. The feedback extraction unit 122 extracts feedback information from the phase-modulated at least one sub-beam. The first processing module 123 uses the feedback information to determine a phasing voltage of at least one of the phasing units 121, and uses the adjusted phasing voltage to control the phasing unit 121 so that a power difference between the two sub-beams after the phasing processing is less than or equal to a participation value.

Alternatively, the control unit 12 includes a first 2×2 optocoupler, M phase modulation units 121, a feedback extraction unit 122, and a first processing module 123, M being greater than or equal to 1. The first 2×2 optical coupler is configured to receive two sub-beams output by the first PSR11, adjust rotation angles of the two sub-beams, output two sub-beams, and the M phase modulation units 121 are configured to perform phase modulation processing on the two sub-beams output by the 2×2 optical coupler, and output the phase-modulated two sub-beams to the first receiving module 90. The feedback extraction unit 122 extracts feedback information from the phase-modulated at least one sub-beam. The first processing module 123 uses the feedback information to determine a phasing voltage of at least one of the phasing units 121, and uses the adjusted phasing voltage to control the phasing unit 121 so that a power difference of the two sub-beams after the phasing processing is less than or equal to a reference value.

It should be noted that, the description of the M phase modulation units 121 refers to the description of the phase modulation units 121 hereinabove, and will not be repeated here.

Alternatively, fig. 19 provides a schematic structural diagram of the first polarization control module 70. Referring to fig. 19, the feedback extraction unit 122 includes a first 1×2 beam splitter 1221, a second 1×2 beam splitter 1222, and a sub extraction unit 1223. The plurality of phase modulation units 121 output phase-modulated two sub-beams, one sub-beam being output to the first 1×2 beam splitter 1221 and the other sub-beam being output to the second 1×2 beam splitter 1222. The first 1×2 beam splitter 1221 splits the received sub-beam into a first sub-beam and a second sub-beam, and outputs the first sub-beam and the second sub-beam to the first receiving module 90 and the sub-extracting unit 1223, respectively. The second 1×2 beam splitter 1222 splits the received sub-beam into a third sub-beam and a fourth sub-beam, and outputs the third sub-beam and the fourth sub-beam to the first receiving module 90 and the sub-extraction unit 1223, respectively. Wherein the power of the first sub-beam is greater than the power of the second sub-beam and the power of the third sub-beam is greater than the power of the fourth sub-beam, and the ratio of the power of the first sub-beam to the power of the second sub-beam is equal to the ratio of the power of the third sub-beam to the power of the fourth sub-beam.

The sub-extraction unit 1223 detects the power of the second sub-beam, and detects the power of the fourth sub-beam, calculates the power difference between the second sub-beam and the fourth sub-beam, and outputs the power difference to the first processing module 123. Or the sub-extraction unit 1223 outputs the power of the second sub-beam and the power of the fourth sub-beam to the first processing module 123.

The first processing module 123 adjusts the phase modulation voltage of the at least one phase modulation unit 121 based on the principle of adjusting the power difference to be less than or equal to the reference value.

Therefore, the power difference between the first component and the second component is smaller, which means that the power of the first component and the power of the second component are relatively close, and the power of two paths of local oscillation light with the same wavelength can be balanced.

Alternatively, fig. 20 provides another schematic structural view of the first polarization control module 70. Referring to fig. 20, the feedback extraction unit 122 includes a first 1×2 beam splitter 1221 and a sub extraction unit 1223. The plurality of phase modulation units 121 output phase-modulated two sub-beams, one sub-beam being output to the first 1×2 splitter 1221 and the other sub-beam being output to the first receiving module 90. The first 1×2 beam splitter 1221 splits a received sub-beam into a first sub-beam and a second sub-beam, and outputs the first sub-beam and the second sub-beam to the first receiving module 90 and the sub-extracting unit 1223, respectively. Wherein the power of the first sub-beam is greater than the power of the second sub-beam.

The sub-extraction unit 1223 receives the second sub-beam, detects the power of the second sub-beam, and outputs the power to the first processing module 123. The first processing module 123 adjusts the phase modulation voltage of at least one phase modulation unit 121 in accordance with the principle of adjusting the power to a target value. Wherein the target value is half of the total power of the first and second sub-beams, such that the power of the second sub-beam is adjusted to the target value, and the power of the first sub-beam is also close to the target value.

In addition, the feedback extraction unit 122 may also include a second 1×2 beam splitter 1222 and a sub extraction unit 1223 to extract the power of the fourth sub beam, for a detailed description referring to the descriptions in fig. 19 and 20.

Optionally, the sub-extraction unit 1223 includes a photodetector that detects power and an ADC that converts the power to an analog signal and sends the analog signal to the first processing module 123. The first processing module 123 determines the phasing voltage indication information, and transmits the phasing voltage indication information, which may be transmitted in the form of an analog signal, to the at least one phasing unit 121.

Illustratively, the polarization state of the third light beam modulated with data is an orthogonal polarization state, and fig. 21 provides a schematic structural diagram of the first receiving module 90. Referring to fig. 21, the first receiving module 90 includes a second PSR21, a first coherent receiving unit 901, and a second processing module 25. The first coherent receiving unit 901 includes a mixer 1, a mixer 2, and a photoelectric conversion module C.

The second PSR21 receives the first signal light, separates the first signal light into a first sub-signal light and a second sub-signal light, the first sub-signal light is a signal light of one polarization state in the received first signal light, the second sub-signal light is a signal light of another polarization state in the first signal light, the one polarization state is orthogonal to the another polarization state, the first sub-signal light includes a third light beam modulated with data, and the second sub-signal light includes a third light beam modulated with data. The first sub-signal light and the second sub-signal light are transmitted to the first coherent receiving unit 901, respectively. The first coherent receiving unit 901 inputs a first component of the first light beam and the first sub-signal light into the mixer 1, performs mixing processing, and outputs an optical signal after the mixing processing to the photoelectric conversion module C, thereby obtaining a first result, which is an electrical signal. And the second component of the first light beam and the second sub-signal are input into the mixer 2 for mixing, and the mixed optical signal is output to the photoelectric conversion module C to obtain a second result, wherein the second result is an electric signal. The first coherent receiving unit 901 transmits the first result and the second result to the second processing module 25. The second processing module 25 uses the first result and the second result to obtain data modulated on the third beam.

Optionally, referring to the first receiving module 90 shown in fig. 21, the second processing module 25 includes a TIA, an ADC, and a third DSP. The TIA amplifies the electrical signal. The ADC converts the amplified electrical signal into a digital signal. The third DSP obtains data modulated on the third light beam from the digital signal.

When the second PSR21 and the first coherent receiving unit 901 are implemented by a silicon optical chip, the second PSR21 converts the signal light in the TM mode polarization mode transmitted by the coherent transmitting apparatus into the signal light in the TE mode polarization mode, so that the first signal light can be transmitted through the silicon optical chip.

Illustratively, after receiving the second light beam, the second polarization control module 80 divides the second light beam into two sub-light beams, and subjects the two sub-light beams to phase modulation processing such that a power difference between the two sub-light beams after the phase modulation processing is less than or equal to a reference value.

Alternatively, fig. 22 provides a schematic structural diagram of the second polarization control module 80. Referring to fig. 22, the second polarization control module 80 includes a fifth PSR801 and a first control unit 802, the fifth PSR801 receiving the second light beam and dividing the second light beam into two sub-light beams. The first control unit 802 performs phase modulation processing on the two sub-beams, that is, adjusts phases of the two sub-beams, extracts feedback information, which may be optical power or the like, from at least one of the sub-beams after the phase modulation processing, and outputs the two sub-beams after the phase modulation processing to the second receiving module 100. The first control unit 802 adjusts the phase modulation voltage subjected to the phase modulation process using the feedback information, and controls the power difference of the two sub-beams subjected to the phase modulation process to be less than or equal to the reference value by the adjusted phase modulation voltage.

Optionally, the first control unit 802 includes M phase modulation units 121, a feedback extraction unit 122, and a fifth processing module 8021, where M is greater than or equal to 1. For example, M has a value of 2.

The M phase modulation units 121 perform phase modulation processing on the two sub-beams output from the fifth PSR801, and output the phase-modulated two sub-beams to the second receiving module 100. The feedback extraction unit 122 extracts feedback information from the phase-modulated at least one sub-beam. The fifth processing module 8021 uses the feedback information to determine the phase modulation voltage of at least one phase modulation unit 121, and uses the phase modulation voltage adjusted to control the phase modulation unit 121 so that the power difference of the two sub-beams after phase modulation processing is less than or equal to the participation value.

It should be noted that, the description of the M phase modulation units 121 is referred to in the foregoing description, and will not be repeated here. The structure of the feedback extraction unit 122 is the same as that of the feedback extraction unit 122 shown in fig. 19 and 20, and will not be described again here.

Optionally, the first control unit 802 may further include a first 2×2 optical coupler, where the first 2×2 optical coupler is located before the M phase modulation units 121 and is adjacent to the M phase modulation units 121, for specific connection relationships, see the description above.

Illustratively, the polarization state of the fourth beam modulated with data is an orthogonal polarization state, in which case fig. 23 provides a schematic diagram of the structure of the second receiving module 100. Referring to fig. 23, the second reception module 100 includes a sixth PSR1001, a second correlation reception unit 102, and a sixth processing module 103. The second correlation receiving unit 102 includes a mixer a, a mixer B, and a photoelectric conversion module D.

The sixth PSR1001 receives the second signal light, separates the second signal light into third sub-signal light and fourth sub-signal light, the third sub-signal light is signal light of one polarization state in the second signal light, the fourth sub-signal light is signal light of another polarization state in the second signal light, the one polarization state is orthogonal to the another polarization state, the third sub-signal light includes a fourth light beam modulated with data, and the fourth sub-signal light includes a fourth light beam modulated with data. The third sub-signal light and the fourth sub-signal light are transmitted to the second correlation receiving unit 102, respectively. The second correlation receiving unit 102 inputs the first component of the second light beam and the third sub-signal light into the mixer a, performs mixing processing, and outputs the optical signal after mixing processing to the photoelectric conversion module D to obtain a third result, where the third result is an electrical signal. And the second component of the second light beam and the fourth sub-signal are input into a mixer B for mixing, the mixed light signal is output to a photoelectric conversion module, and a fourth result which is an electric signal is obtained. The second correlation receiving unit 102 sends the third result and the fourth result to the sixth processing module 103. The sixth processing module 103 uses the third result and the fourth result to obtain data modulated on the fourth light beam.

Optionally, referring to the second receiving module 100 shown in fig. 23, the sixth processing module 103 includes a TIA, an ADC, and a fourth DSP. The TIA amplifies the electrical signal. The ADC converts the amplified electrical signal into a digital signal. The fourth DSP obtains data modulated on the fourth light beam from the digital signal.

When the sixth PSR1001 and the second correlation receiving unit 102 are implemented by a silicon optical chip, the sixth PSR1001 converts the signal light in the TM mode polarization mode transmitted by the coherent transmitting device into the signal light in the TE mode polarization mode, so that the second signal light can be transmitted through the silicon optical chip.

(2) Coherent communication device

The coherent communication device can transmit data to other coherent communication devices using light of the first wavelength and the second wavelength, and can receive data transmitted by other communication devices using light of the third wavelength and the fourth wavelength.

Fig. 24 provides a schematic structural diagram of a coherent communication device. Referring to fig. 24, the coherent communication apparatus includes coherent transmitting means, coherent receiving means, first connecting module 30, and second connecting module 40. The coherent transmission apparatus includes a light source 01, a first transmission module 10, a second transmission module 20, a first connection module 30, and a second connection module 40. The coherent receiving device includes a third polarization control module 001, a fourth polarization control module 002, a third receiving module 003, and a fourth receiving module 004.

The light source 01 outputs the first light beam and the second light beam to the second connection module 40, the light source 01 outputs the third light beam to the first transmission module 10, and the fourth light beam to the second transmission module 20. The first and third light beams have a first wavelength and the second and fourth light beams have a second wavelength.

The second connection module 40 outputs the first light beam and the second light beam, respectively. The first light beam and the second light beam are output through an external optical fiber connected by the second connection module 40.

The first transmitting module 10 modulates data onto the third light beam to obtain the first signal light, and outputs the first signal light to the first connecting module 30. The second transmitting module 20 modulates data onto the fourth light beam to obtain second signal light, and outputs the second signal light to the first connecting module 30.

The first connection module 30 outputs the first signal light and the second signal light, respectively. The first local oscillation light and the second signal light are output through an external optical fiber connected to the first connection module 30.

The second connection module 40 receives a second local oscillation light and a third local oscillation light, wherein the wavelength of the second local oscillation light is a third wavelength, and the wavelength of the third local oscillation light is a fourth wavelength. The second connection module 40 transmits the second local oscillation light to the third polarization control module 001, and transmits the third local oscillation light to the fourth polarization control module 002.

The third polarization control module 001 divides the second local oscillation light into a first component and a second component, and controls the power difference between the first component and the second component to be smaller than or equal to a reference value, wherein the reference value is smaller. The first connection module 30 receives a third signal light, and the wavelength of the third signal light is a third wavelength. The first connection module 30 transmits the third signal light to the third reception module 003. The third receiving module 003 divides the third signal light into two sub-signal lights, and acquires data modulated on the two sub-signal lights using the first component and the second component of the second local oscillation light, respectively.

The fourth polarization control module 002 divides the third local oscillation light into a first component and a second component, and controls the power difference between the first component and the second component to be smaller than or equal to a reference value, which is relatively small. The first connection module 30 receives a fourth signal light having a fourth wavelength of wavelengths. The first connection module 30 transmits the fourth signal light to the fourth reception module 004. The fourth receiving module 004 divides the fourth signal light into two sub-signal lights, and the first component and the second component of the third local oscillation light are used to obtain the data modulated on the two sub-signal lights respectively.

The specific structures of the coherent receiving apparatus and the coherent transmitting apparatus in fig. 24 are described in the foregoing, and are not repeated here.

The embodiment of the present application also provides a coherent communication system shown in fig. 25 on the basis of the coherent communication apparatus shown in fig. 24. Referring to fig. 25, a coherent communication device a and a coherent communication device B communicate. The coherent communication device a transmits data to the coherent communication device B using light of the first wavelength and the second wavelength, and the coherent communication device B receives the data transmitted by the coherent communication device a using local oscillation light of the first wavelength and the second wavelength transmitted by the coherent communication device a. The coherent communication device B transmits data to the coherent communication device a using light of the third wavelength and the fourth wavelength, and the coherent communication device a receives the data transmitted by the coherent communication device B using local oscillation light of the third wavelength and the fourth wavelength transmitted by the coherent communication device B.

In fig. 25, the specific structures of the coherent receiving apparatus and the coherent transmitting apparatus are described in the foregoing, and are not repeated here.

In the embodiment of the application, the design of a homologous coherent system architecture and the tracking and control modes of local oscillation light are provided for a dual-wave coherent communication system.

The above-described modules may be arbitrarily combined without violating logic.

The terms "first," "second," and the like in this disclosure are used for distinguishing between similar elements or items having substantially the same function and function, and it should be understood that there is no logical or chronological dependency between the terms "first," "second," and no limitation on the amount or order of execution. It will be further understood that, although the following description uses the terms first, second, etc. to describe various elements, these elements should not be limited by the terms. These terms are only used to distinguish one element from another element. For example, a first beam may be referred to as a second beam, and similarly, a second beam may be referred to as a first beam, without departing from the scope of the various examples. The first and second beams may both be beams and, in some cases, may be separate and distinct local oscillator lights.

The term "at least one" in the present application means one or more, and the term "plurality" in the present application means two or more.

The foregoing description is merely illustrative of the present application, and the scope of the present application is not limited thereto, and any equivalent modifications or substitutions will be apparent to those skilled in the art within the scope of the present application, and are intended to be included within the scope of the present application. Therefore, the protection scope of the application is subject to the protection scope of the claims.

Claims

1. A coherent receiving device, characterized by comprising a polarization control module (1) and a data receiving module (2);

the polarization control module (1) is used for receiving first local oscillation light, wherein the first local oscillation light comprises a first light beam and a second light beam with orthogonal polarization states, the wavelength of the first light beam is a first wavelength, and the wavelength of the second light beam is a second wavelength;

dividing the first local oscillation light into the first light beam and the second light beam by controlling the polarization state of the first local oscillation light;

the data receiving module (2) is configured to receive a first signal light, where the first signal light includes a third light beam modulated with data and a fourth light beam modulated with data, and a wavelength of the third light beam is the first wavelength and a wavelength of the fourth light beam is the second wavelength;

and acquiring the data modulated on the third light beam by using the first light beam, and acquiring the data modulated on the fourth light beam by using the second light beam.

2. A coherent receiving device according to claim 1, characterized in that the polarization control module (1) is adapted to:

dividing the first local oscillation light into two light beams;

and carrying out phase modulation processing on the two light beams, so that the two light beams after the phase modulation processing are the first light beam and the second light beam respectively.

3. A coherent receiving device according to claim 2, characterized in that the polarization control module (1) comprises a first polarization beam splitter rotator PSR (11) and a control unit (12);

the first PSR (11) is used for receiving first local oscillation light and dividing the first local oscillation light into two light beams;

the control unit (12) is used for carrying out phase modulation processing on the two light beams and outputting the two light beams subjected to phase modulation processing to the data receiving module (2);

extracting feedback information from the phase-modulated at least one light beam;

and adjusting the phase modulation voltage subjected to phase modulation processing based on the feedback information, so that the two light beams subjected to phase modulation processing are the first light beam and the second light beam respectively.

4. A coherent receiving device according to claim 3, characterized in that the control unit (12) comprises N phase modulation units (121), a feedback extraction unit (122) and a first processing module (123), N being greater than or equal to 1;

the N phase modulation units (121) are used for performing phase modulation processing on the two light beams output by the first PSR (11) and outputting the two light beams subjected to phase modulation processing to the data receiving module (2);

the feedback extraction unit (122) is used for extracting feedback information from at least one light beam after phase modulation processing;

The first processing module (123) is configured to adjust a phase modulation voltage of at least one phase modulation unit (121) of the N phase modulation units (121) based on the feedback information, so that two light beams after phase modulation processing are the first light beam and the second light beam, respectively.

5. The coherent receiving device according to claim 4, wherein the 1 st to N-th phase modulation units (121) of the N phase modulation units (121) are sequentially arranged along the local oscillation optical transmission direction, N being greater than 1;

each phase modulation unit (121) comprises a phase modulator (1211) and a 2 x 2 optical coupler (1212);

the input port and the output port of the phase modulator (1211) in the 1 st phase modulation unit (121) are respectively connected with one output port of the first PSR (11) and the first input port of the 2 x 2 optical coupler (1212) in the 1 st phase modulation unit (121); a second input port of the 2 x 2 optical coupler (1212) in the 1 st phase modulation unit (121) is connected to another output port of the first PSR (11);

two output ports of the 2 multiplied by 2 optical coupler (1212) in the i-1 phase modulation unit (121) are respectively connected with an input port of the phase modulator (1211) in the i-1 phase modulation unit (121) and a first input port of the 2 multiplied by 2 optical coupler (1212);

The output port of the phase modulator (1211) in the i-1 phase modulation unit (121) is connected with the second input port of the 2 x 2 optical coupler (1212), i is greater than 1 and less than or equal to N;

two output ports of the 2 x 2 optical coupler (1212) in the nth phase modulation unit (121) are respectively connected with the feedback extraction unit (122);

-the first processing module (123) for adjusting a phase modulation voltage of a phase modulator (1211) in the at least one phase modulation unit (121) based on the feedback information.

6. The coherent receiving device according to claim 4 or 5, wherein the feedback extraction unit (122) comprises a first 1 x 2 beam splitter (1221), a second 1 x 2 beam splitter (1222) and a sub-extraction unit (1223);

the N phase modulation units (121) are configured to output two phase-modulated light beams to the first 1×2 optical splitter (1221) and the second 1×2 optical splitter (1222), respectively;

the first 1×2 beam splitter (1221) is configured to split one beam after phase modulation into a first sub-beam and a second sub-beam, and output the first sub-beam and the second sub-beam to the data receiving module (2) and the sub-extraction unit (1223), respectively;

the second 1×2 beam splitter (1222) is configured to split the other beam after the phase modulation process into a third sub-beam and a fourth sub-beam, and output the third sub-beam and the fourth sub-beam to the data receiving module (2) and the sub-extraction unit (1223), respectively;

-the sub-extraction unit (1223) is configured to determine a target power comprising the sum of the power of the light of the second wavelength in the second sub-beam and the power of the light of the first wavelength in the fourth sub-beam or comprising the power of the light of the second wavelength in the second sub-beam and the power of the light of the first wavelength in the fourth sub-beam;

the first processing module (123) is configured to adjust a phase modulation voltage of the at least one phase modulation unit (121) so that a wavelength of the first sub-beam is the first wavelength and a wavelength of the third sub-beam is the second wavelength based on a principle of adjusting the target power to a minimum value.

7. The coherent receiving device according to claim 4, wherein the feedback extraction unit (122) comprises a first 1 x 2 beam splitter (1221) and a sub-extraction unit (1223);

the N phase modulation units (121) are configured to output two phase-modulated light beams to the first 1×2 optical splitter (1221) and the data receiving module (2), respectively;

the first 1×2 beam splitter (1221) is configured to split a received light beam into a first sub-beam and a second sub-beam, and output the first sub-beam and the second sub-beam to the data receiving module (2) and the sub-extraction unit (1223), respectively;

-the sub-extraction unit (1223) is adapted to determine the power of light of the second wavelength in the second sub-beam;

the first processing module (123) is configured to adjust a phase modulation voltage of the at least one phase modulation unit (121) so that a wavelength of the first sub-beam is the first wavelength based on a principle of adjusting the power to a minimum value.

8. The coherent receiving device according to any one of claims 1 to 7, wherein the polarization state of the third light beam modulated with data is an orthogonal polarization state and the polarization state of the fourth light beam modulated with data is an orthogonal polarization state;

the data receiving module (2) comprises a second PSR (21), a first wave-dividing module (22), a second wave-dividing module (23), a coherent receiving unit (24) and a second processing module (25);

the second PSR (21) is used for receiving the first signal light and dividing the first signal light into first sub-signal light and second sub-signal light;

the first branching module (22) is configured to separate the first sub-signal light into the signal light of the first wavelength and the signal light of the second wavelength;

the second wave splitting module (23) is configured to split the second sub-signal light into the signal light of the first wavelength and the signal light of the second wavelength;

The coherent receiving unit (24) is configured to perform coherent reception on the signal light with the first wavelength by using the first light beam to obtain a first result, and perform coherent reception on the signal light with the second wavelength by using the second light beam to obtain a second result;

the second processing module (25) is configured to obtain data modulated on the third and fourth light beams based on the first and second results.

9. A coherent transmission device, characterized by comprising a light source (01), a polarization changing module (02) and a data transmission module (03);

the light source (01) is used for outputting a first light beam, a second light beam, a third light beam and a fourth light beam, wherein the wavelengths of the first light beam and the third light beam are first wavelengths, and the wavelengths of the second light beam and the fourth light beam are second wavelengths;

the polarization changing module (02) is used for combining the first light beam and the second light beam into a first local oscillation light with orthogonal polarization states and outputting the first local oscillation light;

the data transmitting module (03) is configured to modulate data onto the third light beam and the fourth light beam, obtain first signal light, and output the first signal light.

10. The coherent transmission apparatus according to claim 9, wherein said data transmission module (03) comprises a processing module (030), a first modulator (031), a second modulator (032), a first wave combining module (033), a second wave combining module (034) and a polarization beam splitting rotator PSR (035);

-the processing module (030) is configured to provide the data;

the first modulator (031) is configured to divide the third beam into a first sub-beam and a second sub-beam, and modulate data onto the first sub-beam and the second sub-beam, respectively;

the second modulator (032) is used for dividing the fourth light beam into a third sub-light beam and a fourth sub-light beam, and modulating data onto the third sub-light beam and the fourth sub-light beam respectively;

the first wave combining module (033) is configured to combine the first path of sub-beam modulated with data and the third path of sub-beam modulated with data into first sub-signal light;

the second wave combining module (034) is configured to combine the second sub-beam modulated with data and the fourth sub-beam modulated with data into second sub-signal light;

the PSR (035) is used for adjusting the polarization state of the first sub-signal light to be orthogonal to the polarization state of the second sub-signal light, and combining the first sub-signal light and the second sub-signal light after the polarization state is adjusted to obtain the first signal light.

11. A coherent communication system, characterized by comprising a coherent transmitting device and a coherent receiving device which are connected through an optical fiber, wherein the coherent transmitting device comprises a light source (01), a polarization changing module (02) and a data transmitting module (03), and the coherent receiving device comprises a polarization control module (1) and a data receiving module (2);

the data transmitting module (03) is configured to modulate data onto the third light beam and the fourth light beam to obtain first signal light, and output the first signal light;

the polarization control module (1) is used for receiving the first local oscillation light; dividing the first local oscillation light into the first light beam and the second light beam by controlling the polarization state of the first local oscillation light;

the data receiving module (2) is used for receiving the fourth light beam; and acquiring the data modulated on the third light beam by using the first light beam, and acquiring the data modulated on the fourth light beam by using the second light beam.

12. A coherent communication system according to claim 11, characterized in that the polarization control module (1) is adapted to:

dividing the first local oscillation light into two light beams;

13. A coherent communication system according to claim 12, characterized in that the polarization control module (1) comprises a first polarization beam splitter rotator PSR (11) and a control unit (12);

14. A coherent communication system according to claim 13, characterized in that said control unit (12) comprises N phase modulation units (121), a feedback extraction unit (122) and a first processing module (123), N being greater than or equal to 1;

15. The coherent communication system according to claim 14, wherein the feedback extraction unit (122) comprises a first 1 x 2 optical splitter (1221), a second 1 x 2 optical splitter (1222) and a sub-extraction unit (1223);

16. The coherent communication system according to claim 14, wherein the feedback extraction unit (122) comprises a first 1 x 2 beam splitter (1221) and a sub-extraction unit (1223);