CN115327800A - Modulator, light emitting assembly, silicon optical module and working point locking method thereof - Google Patents

Abstract

The invention discloses a modulator, a light emitting component, a silicon optical module and a working point locking method thereof, wherein the modulator comprises at least one path of optical channel, each path of optical channel is provided with two parallel modulation arms, the combined light of the two modulation arms on each path of optical channel passes through a 2-in-2 MMI structure and outputs two paths of light according to the difference of phases, each path of optical channel corresponds to two MPD detection units, and the two MPD detection units respectively convert a first path of optical signal and a second path of optical signal output by the MMI structure into current signals to be output. The modulator is electrically connected with the control unit and the DSP unit, a modulation arm of the modulator is used for receiving an electric signal of the DSP unit and modulating the optical signal, and two MPD detection units of each optical channel of the modulator respectively transmit output photocurrents MPDXB and MPDXD to the control unit. The invention ensures that the light module works stably under various environmental temperatures by ensuring that the values of MPDXB and MPDXD of all light channels of the silicon light modulator are constant and ensuring that the light current value of MPDXB of all light channels is equal to the light current value of MPDXD.

Description

Modulator, light emitting assembly, silicon optical module and working point locking method thereof

Technical Field

The invention belongs to the technical field of optical communication, and particularly relates to a modulator, a light emitting assembly, a silicon optical module and a working point locking method thereof.

Background

The 5G bearing and data center construction puts forward strong demands on high speed, small size, low cost and low power consumption of the optical module. The single-wave 100Gb/s technology can effectively realize higher interface density and low cost while meeting the same bandwidth requirement and reducing optical complexity by means of bandwidth promotion and iterative evolution of a photoelectric chip and highly integrated process and package. In the aspect of packaging, QSFP-DD MSA and OSFP MSA respectively release QSFP-DD and OSFP specifications of 400Gb/s, and an 8 x 56Gb/s electrical interface is adopted. QSFP-DD MSA, in turn, released a version 6.01 specification in 2021 with an upgrade that contained 400Gb/s QSFP 112. The QSFP112 MSA established by the Abibaba and Baidu in China also issues related specifications to promote the interconnection application of data centers in China. The applicant designs a first generation 400Gb/s optical module based on single wave 100Gb/s, which is mainly based on an 8 x 56Gb/s electrical interface and needs to adopt a DSP to realize that 8:4 georbox rate conversion. The applicant designs a second generation 400Gb/s optical module to adopt a 4x 112Gb/s electrical interface, which can simplify the butt joint of the exchange chip and the optical module, thereby reducing the power consumption and the cost.

In the aspect of optical interface technology, a 400Gb/s 500m DR4 optical module based on single-mode optical fiber is put into commercial use, and three schemes of EML, DML and silicon optical exist. Among them, the EML scheme is the most mature conventional scheme. In the 2020 year, lumentum issues 100Gb/s PAM4 DML chips, which provides powerful support for DML schemes, and the schemes need to ensure the bandwidth performance at commercial temperature (0-70 ℃) through temperature control. Silicon optical schemes of various manufacturers in the industry are not uniform and show fragmentation, and certain challenges are brought to the formation of scale advantages. The scheme of EML + TEC/DML + TEC is mainly adopted for the 400Gbps optical module in the current market, but the silicon optical module does not need TEC, so that high speed, low cost and low power consumption can be realized to adapt to market demands, and the silicon optical module can cause the drift of the working point of the module when the working environment changes. Therefore, it is necessary to design a 400G silicon optical module with a single channel transmission rate of 100Gbps and a silicon optical modulator of the silicon optical module, etc. with satisfactory performance.

Disclosure of Invention

The invention aims to overcome at least one defect in the prior art and provides a modulator, a light emitting assembly, a silicon optical module and a working point locking method thereof.

The technical scheme of the invention is realized as follows: the invention discloses a modulator, which comprises at least one optical channel, wherein each optical channel is provided with two parallel modulation arms, the combined light of the two modulation arms on each optical channel passes through a 2-in-2 MMI structure and outputs two paths of light according to different phases, each optical channel corresponds to two MPD detection units, the first MPD detection unit is used for converting a first path of optical signal output by the MMI structure into a current signal for output, and the second MPD detection unit is used for converting a second path of optical signal output by the MMI structure into a current signal for output.

Furthermore, a first optical signal output by the MMI structure of each optical channel is divided into detection light and signal light by a first output splitter, the first MPD detection unit is configured to convert the detection light signal output by the first output splitter into a current signal for output, a second optical signal output by each MMI structure is divided into detection light and signal light by a second output splitter, the second MPD detection unit is configured to convert the detection light signal output by the second output splitter into a current signal for output, and the signal light output by the second output splitter is output as the signal light of the optical channel.

Further, the modulation arm is used for receiving an electric signal and modulating an optical signal;

the modulator is provided with a branching unit, the branching unit comprises at least one input end branching unit, and the branching unit is used for dividing at least one path of optical input into at least two paths of optical output which correspond to the multiple paths of optical channels one to one.

Furthermore, the modulator is provided with at least one optical input end and a plurality of optical output ends, the number of the optical output ends of the modulator is the same as the number of the optical channels, when each input end branching unit has one input end and at least two output ends, the number of the input end branching units is the same as the number of the optical input ends of the modulator, the input ends of the input end branching units correspond to the optical input ends of the modulator one to one, each output end of the input end branching unit corresponds to the input end of each optical channel one to one, and the output end of each optical channel corresponds to the optical output end of each modulator one to one.

The invention discloses a light emitting component, which comprises at least one laser and the modulator, wherein the light input end of the modulator corresponds to the laser one by one, and the modulator is used for receiving laser output by the at least one laser and outputting at least two paths of modulated optical signals.

Further, the optical transmit module of the present invention further comprises a transmit end module for receiving the optical signal output from the optical output of the modulator and coupled to the optical fiber.

The invention discloses a silicon optical module which comprises the light emitting assembly, wherein a modulator of the light emitting assembly is electrically connected with a control unit and a DSP (digital signal processor) processing unit, a modulation arm of the modulator is used for receiving an electric signal of the DSP processing unit and modulating the optical signal, and two MPD detection units of each optical channel of the modulator are used for respectively transmitting output photocurrents MPDXB and MPDXD to the control unit.

Furthermore, a switch selection circuit and a collection circuit are arranged between the modulator and the control unit, the switch selection circuit is provided with a plurality of input ends and an output end, the plurality of input ends of the switch selection circuit are respectively electrically connected with the plurality of MPD detection units in a one-to-one correspondence manner and are used for switching the photocurrent output by the plurality of MPD detection units into any photocurrent output, the output end of the switch selection circuit is electrically connected with the input end of the collection circuit, and the collection circuit is used for converting a selected photocurrent into a sampling voltage and then inputting the sampling voltage to the control unit through an operational amplifier.

Furthermore, the laser is used for receiving the driving current, and the sum of the MPDXB and the MPDXD of each optical channel of the modulator is equal to the target value of the optical channel or the phase difference is in the error allowable range by adjusting the driving current of the laser corresponding to each optical channel, so as to realize the automatic power control function;

each light channel of the modulator is used for receiving heater voltage to realize the adjustment of the working point of each light channel of the modulator, and the MPDXB light current value of the X-ray channel is equal to the MPDXD light current value or the difference between the MPDXD light current value and the MPDXD light current value is in the range allowed by the error through the adjustment of the heater voltage received by the X-ray channel to realize the locking of the working point of the X-ray channel.

The invention discloses a working point locking method of a silicon optical module, which comprises the following steps:

acquiring photocurrent values MPDXB and MPDXD of each optical channel of the modulator in real time at any working temperature, and adjusting the driving current of the laser in real time to ensure that the sum of the MPDXB and the MPDXD of each optical channel of the modulator is equal to the target value corresponding to the optical channel or the difference is within an error allowable range;

and under any working temperature, adjusting the heater voltage of each optical channel of the modulator in real time to enable the MPDXB optical current value and the MPDXD optical current value of each optical channel to be equal or have a difference within an error allowable range.

The invention has at least the following beneficial effects: the silicon optical modulator adopted by the invention comprises at least one optical channel, each optical channel is provided with two parallel modulation arms, the combined light of the two modulation arms passes through a 2-in-2 MMI structure, and two paths of light are output according to the difference of phases: phase 1 light and phase 2 light. 3% of the phase 1 light was detected with MPDXB and 97% of the phase 1 light was useless. 3% of the phase 2 light is detected by MPDXD, and 97% of the phase 2 light is output as signal light. The modulation arm of the modulator is used for receiving an electric signal of the DSP processing unit and modulating the optical signal, and the two MPD detection units of each optical channel are used for respectively transmitting the output photocurrents MPDXB and MPDXD to the control unit. According to photocurrents MPDXB and MPDXD corresponding to each optical channel monitored by an MPD detection unit, the Automatic Power Control (APC) function is realized by locking the values of MPDXB + MPDXD of each optical channel of a silicon optical modulator (such as the values of MPD1B + MPD1D and MPD3B + MPD 3D), and the working point locking of each optical channel is realized by locking the MPDXB optical current value of each optical channel to be equal to the MPDXD optical current value (namely MPD1B = MPD1D, MPD2B = MPD2D, MPD3B = MPD3D and MPD4B = MPD 4D). By adopting the scheme, the 400G silicon optical module with the single-channel transmission rate of 100Gbps can stably work at different environmental temperatures, and the module performance meets the requirements of IEEE 802.3.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a modulator provided by an embodiment of the present invention;

FIG. 2 is a schematic diagram of a transmitting portion provided by an embodiment of the present invention;

FIG. 3 is a circuit diagram of a switch selection circuit and an acquisition circuit according to an embodiment of the present invention;

fig. 4 is a system block diagram of a silicon optical module according to an embodiment of the present invention;

fig. 5 is a flowchart of a method for locking a working point of a silicon optical module according to an embodiment of the present invention;

fig. 6 is a schematic diagram of a module provided in an embodiment of the present invention at an operating point.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of the present invention, the meaning of "plurality" or "a plurality" is two or more unless otherwise specified.

Example one

Referring to fig. 1, an embodiment of the present invention provides a modulator, including at least one optical channel, where each optical channel is provided with two parallel modulation arms, and a combined light of the two modulation arms on each optical channel passes through a 2-in-2 MMI structure, and outputs two lights according to different phases, where the two lights are phase 1 light and phase 2 light, and each optical channel corresponds to two MPD detection units (similar to functions of photodiodes), where a first MPD detection unit is configured to convert a first optical signal, i.e., phase 1 light, output by the MMI structure into a current signal for output, and a second MPD detection unit is configured to convert a second optical signal, i.e., phase 2 light, output by the MMI structure into a current signal for output.

Further, the first path of optical signal, i.e. phase 1 light, output by the MMI structure of each optical channel is divided into detection light (3% of phase 1 light) and signal light (97% of phase 1 light) by the first output splitter, the first MPD detection unit is configured to convert the detection optical signal (3% of phase 1 light) output by the first output splitter into a current signal MPDXB for output, and the signal optical signal (97% of phase 1 light) output by the first output splitter is useless.

The second path of optical signals, i.e., phase 2 light, output by each MMI structure is divided into detection light (3% of phase 2 light) and signal light (97% of phase 2 light) by a second output splitter, the second MPD detection unit is configured to convert the detection optical signals (3% of phase 2 light) output by the second output splitter into current signals MPDXD for output, and the signal light (97% of phase 2 light) output by the second output splitter is output as the signal light of the optical channel.

Each optical channel is provided with an MPD detection unit (MPD unit) for detecting optical power. The MPD detection unit outputs a current related to the light magnitude.

The phase modulation of the two branches of the MZM modulator is related to the electro-optical characteristic of the substrate, and the phase change of each branch is converted into the change of the output optical power of the two paths of combined light.

The MZM modulator is voltage-phase modulation, different voltage phases are different, the MZM combined light intensity with the same phase is increased, the phase is opposite, and the MZM combined light intensity is offset. A bias voltage is applied to one electrode of the modulation arm, the other electrode of the modulation arm is connected with a high-speed electric signal, and a Heater voltage is used for changing the phase of light in the modulation arm. The haeer voltage corresponds to the phase of the heat-altered light, and the 2-in-2 MMI structure outputs two paths of light: when the phase 1 light and the phase 2 light are equal in phase, i.e., MPDXB = MPDXD, the module is at the operating point, which is about half the maximum light.

Further, the modulation arm is used for receiving the electric signal and modulating the optical signal.

Furthermore, the modulator is provided with a splitting unit, the splitting unit includes at least one input splitter, and the splitting unit is configured to split at least one optical input into at least two optical outputs, which correspond to the multiple optical channels one to one.

Further, the modulator is provided with at least one optical input end and a plurality of optical output ends, the number of the optical output ends of the modulator is the same as the number of the optical channels, when each input end branching unit has one input end and at least two output ends, the number of the input end branching units is the same as the number of the optical input ends of the modulator, the input ends of the input end branching units correspond to the optical input ends of the modulator one to one, each output end of the input end branching unit corresponds to the input end of each optical channel one to one, and the output end of each optical channel corresponds to the optical output end of each modulator one to one.

When the optical module is a four-path optical channel, two lasers can be used, and an optical signal sent by a first laser enters a silicon optical modulator and is divided into 2 optical channels by a first input end splitter, wherein the optical channels are a first optical channel and a second optical channel. And an optical signal sent by the second laser enters the silicon optical modulator and is equally divided into 2 optical channels by the second input end splitter, wherein the optical channels are a third optical channel and a fourth optical channel. Each channel can transmit 100Gbps of optical signal, so only two lasers are needed to realize 4X100Gbps. Of course, 1 high power laser may be used, divided into 4 paths. Both approaches can achieve 400G. If the light is not split, 4 lasers are needed for 4 channels, and the cost is high. 800G can be implemented using 4 lasers and an MZ silicon optical modulator containing 8 modulated optical channels.

The modulator comprises 4 paths of modulation optical channels, each path of modulation optical channel comprises two modulation arms, the combined light of the two modulation arms passes through a 2-in-2 MMI, and two paths of light are output according to different phases: phase 1 light and phase 2 light. 3% of the phase 1 light was detected with MPDXB and 97% of the phase 1 light was useless. 3% of the phase 2 light is detected by MPDXD, and 97% of the phase 2 light is output as signal light. The silicon optical MZ modulator comprises 8 MPD units including MPD1B, MPD1D, MPD2B, MPD2D, MPD3B, MPD3D, MPD4B and MPD 4D. The silicon optical MZ modulator is used for receiving high-speed electric signals, modulating optical signals, and outputting the modulated 4 paths of optical signals from the silicon optical MZ modulator.

When the first input splitter splits the light into the first channel and the second channel, the light of the first optical channel and the light of the second optical channel are approximately equal, and controlling the value of the optical power current of the first optical channel is equivalent to controlling the value of the optical power current of the second optical channel.

When the second input splitter splits the light into the third optical channel and the fourth optical channel, the light of the third optical channel and the light of the fourth optical channel are approximately equal, and controlling the third optical channel is equivalent to controlling the light power current value of the fourth optical channel.

Example two

Referring to fig. 1 and fig. 2, an optical transmission assembly according to an embodiment of the present invention includes at least one laser, and further includes a modulator according to the first embodiment, where optical input ends of the modulator correspond to the lasers one to one, and the modulator is configured to receive laser light output by the at least one laser and output at least two paths of modulated optical signals.

Further, the optical transmission module of the present invention further comprises a transmitting side module for receiving the optical signal outputted from the optical output terminal of the modulator and coupled to a FA (fiber array).

Furthermore, the laser, the modulator and the transmitting end component are fixed on a substrate.

Furthermore, a first lens, an isolator and a second lens are arranged between each laser and the light input end of the modulator, and light signals emitted by the lasers enter the light input end of the modulator through the first lens, the isolator and the second lens or the first lens, the second lens and the isolator in a coupling mode. The first lens is used for diverging the optical signal emitted by the laser, the isolator is used for reducing reflection of the optical signal, the second lens is used for condensing the optical signal, coupling tolerance can be increased through the first lens, the isolator and the second lens, and coupling efficiency is improved. If the optical path is arranged in the order of the first lens, the second lens and the isolator, the optical path can be shortened by 1mm relative to the former.

Further, the first lens, the isolator and the second lens are also fixed on the substrate.

EXAMPLE III

Referring to fig. 1 to 4, the embodiment of the invention discloses a 400G silicon optical module with low power consumption, low cost, transmission distance of 2km and single-channel transmission rate of 100Gbps, which is suitable for data center applications. The silicon optical module comprises a power management circuit, an electrical interface circuit, an optical receiving assembly, a control unit, a DSP processing unit and the optical transmitting assembly according to the second embodiment, wherein a modulator of the optical transmitting assembly is electrically connected with the control unit and the DSP processing unit, a modulation arm of the modulator is used for receiving an electric signal of the DSP processing unit and modulating the optical signal, and two MPD detection units of each optical channel of the modulator are used for respectively transmitting output photocurrents MPDXB and MPDXD to the control unit.

The power supply management circuit is used for supplying power to the whole optical module, and the electrical interface circuit, the light emitting assembly and the light receiving assembly are electrically connected with the DSP processing unit; the control unit is electrically connected with the DSP processing unit. The control unit adopts MCU.

The optical receiving assembly comprises an optical detector and a TIA (three-dimensional interactive application), wherein the optical detector is used for converting an optical signal into an electrical signal and transmitting the electrical signal to the TIA, and the TIA is used for amplifying the electrical signal and outputting the electrical signal to the DSP (digital signal processor); the optical receiving assembly further comprises a receiving end assembly for coupling the received optical signal into the optical detector;

a silicon lens is arranged between the receiving end component and the optical detector, and the receiving end component is used for coupling the received optical signal into the optical detector through the silicon lens; the silicon lens is fixed on the silicon gasket. The role of the silicone is to concentrate light. The transmitting end component and the receiving end component adopt the prior art.

Furthermore, a switch selection circuit and a collection circuit are arranged between the modulator and the control unit, the switch selection circuit is provided with a plurality of input ends and an output end, the plurality of input ends of the switch selection circuit are respectively electrically connected with the plurality of MPD detection units in a one-to-one correspondence manner and are used for switching the photocurrent output by the plurality of MPD detection units into any photocurrent output, the output end of the switch selection circuit is electrically connected with the input end of the collection circuit, and the collection circuit is used for converting a selected photocurrent into a sampling voltage and then inputting the sampling voltage to the control unit through an operational amplifier. The acquisition circuit includes that the fortune is put and be used for the sampling circuit of converting current signal into voltage signal, sampling circuit's input and switch selection circuit's output are connected, and voltage sampling circuit's output is connected with the input that the fortune was put, and the output (output ADC value) that the fortune was put is connected with the control unit electricity.

The switch selection circuit adopts a change-over switch chip U15, a plurality of input ends of the change-over switch chip U15 are respectively and electrically connected with a plurality of MPD detection units of the modulator in a one-to-one correspondence manner, and an output end of the change-over switch chip U15 is electrically connected with an input end of the acquisition circuit. The control end of the switch chip U15 is electrically connected with the control unit, and the control unit controls the connection or disconnection of each channel of the switch chip.

The acquisition circuit includes that the fortune is put U13, the homophase output end that the fortune was put U13 and the one end of resistance R34, the one end of resistance R33 is connected, the other end ground connection of resistance R33, the other end and the one end of voltage VEEF and resistance R35 of resistance R34, the one end of electric capacity C174 is connected, the other end ground connection of electric capacity C174, the other end and the output of change over switch chip of resistance R35 are connected, the inverting output of fortune is put U13 respectively with the one end of resistance R36, the one end of resistance R60, the one end of resistance R37, the one end of electric capacity C234 is connected, the other end and the P4 wiring end of resistance R36 are connected, the output and the P4 wiring end of change over switch chip are connected, the other end ground connection of resistance R60, the other end of resistance R37, the other end of electric capacity C234 all is connected with the output that the fortune was put U13. The P4 wiring end is a reserved detection point, can be measured by a probe, and is convenient to detect.

Further, the current source or the control unit or the DAC chip controlled by the control unit outputs the laser driving current LD BIAS to the laser, thereby realizing the regulation of the light emitting intensity of the laser. The invention can use DAC chip outputting hundreds of mA current to output laser drive current LD BIAS to laser, or use amplifier to build current source circuit to output laser drive current LD BIAS to laser.

The control unit or the DAC chip controlled by the control unit outputs the DAC value as a heater voltage, thereby adjusting the working point.

The modulator is supplied with the required bias voltage VB via a power management circuit. The invention can also use the voltage source built by the DAC chip and the amplifier to output the DAC value as the heater voltage.

Further, the laser is configured to receive a driving current, and adjust the driving current of the laser corresponding to each optical channel to make the sum of the MPDXB and the MPDXD of each optical channel of the modulator equal to a target value corresponding to the optical channel or make a phase difference between the target value and the target value within an error tolerance range (where the error tolerance range is set as needed), so as to implement an automatic power control function, where X is a positive integer greater than or equal to 1 and less than or equal to N, and N is the number of optical channels of the modulator.

Each optical channel of the modulator is used for receiving a heater voltage to realize the adjustment of the working point of each optical channel of the modulator, and the MPDXB optical current value of the X-ray channel is equal to the MPDXD optical current value or has a difference within an error allowable range (the error allowable range is set as required) by adjusting the heater voltage received by the X-ray channel to realize the locking of the working point of the X-ray channel.

Theoretically, when the MPDXB photocurrent value of the X-ray channel is equal to the MPDXD photocurrent value, the Heater is considered to be in a normal operating point state, otherwise, the Heater voltage needs to be adjusted to recover to the normal operating state.

The haeer voltage is equivalent to heating to change the phase of light, and 2 is divided into 2 to output two paths of light from MMI: when the phase 1 light and the phase 2 light are equal, i.e., MPDXB = MPDXD, the module is at the operating point, which is about half of the maximum light, as shown in fig. 6.

Example four

Referring to fig. 5, an embodiment of the present invention discloses a method for locking a working point of a silicon optical module, including the following steps:

determining a target value corresponding to each optical channel;

acquiring photocurrent values MPDXB and MPDXD of each optical channel of the modulator in real time at any working temperature, and adjusting the driving current of the laser in real time to enable the sum of the MPDXB and the MPDXD of each optical channel of the modulator to be equal to a target value corresponding to the optical channel (the phase difference is also equal to the default value within an error allowable range);

and under any working temperature, adjusting the heater voltage of each optical channel of the modulator in real time to enable the MPDXB optical current value and the MPDXD optical current value of each optical channel to be equal (the phase difference is also equal by default in an error allowable range).

The basic principle of working point locking is to judge according to the light current values of MPDxB and MPDxD of the monitoring channel, when the light current values are equal, the Heater is considered to be in a normal working point state, otherwise, the Heater voltage is required to be adjusted to recover to the normal working state.

The target value corresponding to each optical channel is determined according to the following method: and adjusting the heater voltage of each path of the modulator, the driving current of each laser and DSP configuration to enable the transmitting end indexes of each path to be within an acceptable range, and recording the MPDXB + MPDXD of each optical channel of the modulator at the moment as a corresponding target value.

The embodiment of the invention provides a 400G silicon optical module with low power consumption, low cost and a single-channel transmission rate of 100Gbps, which is suitable for application of a data center. According to the invention, the stable operation of the optical module at different environmental temperatures is realized through the scheme.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (10)

1. A modulator, characterized by: the device comprises at least one optical channel, wherein each optical channel is provided with two parallel modulation arms, the combined light of the two modulation arms on each optical channel passes through a 2-in-2 MMI structure and outputs two paths of light according to different phases, and each optical channel corresponds to two MPD detection units, wherein the first MPD detection unit is used for converting a first path of optical signal output by the MMI structure into a current signal for output, and the second MPD detection unit is used for converting a second path of optical signal output by the MMI structure into a current signal for output.

2. The modulator of claim 1, wherein: the first path of optical signal output by the MMI structure of each path of optical channel is divided into detection light and signal light by the first output end splitter, the first MPD detection unit is configured to convert the detection optical signal output by the first output end splitter into a current signal for output, the second path of optical signal output by each MMI structure is divided into detection light and signal light by the second output end splitter, the second MPD detection unit is configured to convert the detection optical signal output by the second output end splitter into a current signal for output, and the signal light output by the second output end splitter is used as the signal light output of the path of optical channel.

3. The modulator of claim 1, wherein: the modulation arm is used for receiving the electric signal and modulating the optical signal;

the modulator is provided with a branching unit, the branching unit comprises at least one input end branching unit, and the branching unit is used for dividing at least one path of optical input into at least two paths of optical output which correspond to the multiple paths of optical channels one to one.

4. The modulator of claim 1, wherein: the modulator is provided with at least one optical input end and a plurality of optical output ends, the number of the optical output ends of the modulator is the same as that of the optical channels, when each input end branching unit has one input end and at least two output ends, the number of the input end branching units is the same as that of the optical input ends of the modulator, the input ends of the input end branching units correspond to the optical input ends of the modulator one to one, each output end of the input end branching unit corresponds to the input end of each optical channel one to one, and the output end of each optical channel corresponds to the optical output end of each modulator one to one.

5. An optical transmit assembly comprising at least one laser, characterized by: the modulator of claims 1 to 4, wherein the optical input ends of the modulator correspond to the lasers in a one-to-one manner, and the modulator is configured to receive laser light output by at least one laser and output at least two paths of modulated optical signals.

6. The light emitting assembly of claim 5, wherein: also included is a transmit end assembly for receiving the optical signal output from the optical output of the modulator and coupled to the optical fiber.

7. A silicon optical module is characterized in that: the optical transmission assembly of claim 5 or 6, wherein the modulator of the optical transmission assembly is electrically connected to the control unit and the DSP processing unit, the modulation arm of the modulator is configured to receive an electrical signal from the DSP processing unit and modulate the optical signal, and the two MPD detection units of each optical channel of the modulator are configured to respectively transmit the output photocurrents MPDXB and MPDXD to the control unit.

8. The silicon optical module according to claim 7, wherein: the switch selection circuit is provided with a plurality of input ends and an output end, the plurality of input ends of the switch selection circuit are respectively electrically connected with the plurality of MPD detection units in a one-to-one correspondence mode and used for switching light currents output by the plurality of MPD detection units into any light current output, the output end of the switch selection circuit is electrically connected with the input end of the acquisition circuit, and the acquisition circuit is used for converting a selected light current into sampling voltage and then inputting the sampling voltage to the control unit through the operational amplifier.

9. The silicon optical module according to claim 7, wherein: the laser is used for receiving the driving current, and the sum of MPDXB and MPDXD of each optical channel of the modulator is equal to the target value of the optical channel or the difference is in the range of error allowance by adjusting the driving current of the laser corresponding to each optical channel, so that the automatic power control function is realized;

each optical channel of the modulator is used for receiving a heater voltage to realize the adjustment of the working point of each optical channel of the modulator, and the MPDXB optical current value and the MPDXD optical current value of the X-ray channel are equal or have a difference within an error allowable range through the adjustment of the heater voltage received by the X-ray channel to realize the locking of the working point of the X-ray channel.

10. The method for locking the working point of the silicon optical module is characterized by comprising the following steps:

acquiring photocurrent values MPDXB and MPDXD of each optical channel of the modulator in real time at any working temperature, and adjusting the driving current of the laser in real time to ensure that the sum of the MPDXB and the MPDXD of each optical channel of the modulator is equal to the target value corresponding to the optical channel or the difference is in an error allowable range;

and under any working temperature, adjusting the heater voltage of each optical channel of the modulator in real time to enable the MPDXB optical current value and the MPDXD optical current value of each optical channel to be equal or have a difference within an error allowable range.

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