CN111491220B - Optical network node of ultra-dense wavelength division multiplexing passive optical network - Google Patents
Optical network node of ultra-dense wavelength division multiplexing passive optical network Download PDFInfo
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Abstract
The invention discloses an optical network node of an ultra-dense wavelength division multiplexing passive optical network, which comprises a 1 x 2n coupler, wherein n optical network nodes with the same structure are connected with the 1 x 2n coupler, each optical network node is respectively and independently connected with two output ports of the 1 x 2n coupler, one port recovers optical carriers in an optical injection locking mode, the recovered optical carriers are divided into two paths, one path is used as local oscillation light to form a coherent detection loop with signal light transmitted by the other port, downlink data signals are demodulated, and the other path modulates uplink user data and transmits the uplink user data. The invention has the beneficial effects that: the active filtering mode of the injection locking semiconductor laser is adopted to ensure the discrimination between user data under a tiny wavelength interval and provide high-quality local oscillation light for homodyne coherent detection; the recovered optical carrier is used for modulating uplink data, so that the utilization rate of the spectrum is improved; and ensures the synchronization of uplink wavelength; finally, the method provides green, efficient and high-speed broadband access service for users.
Description
Technical Field
The invention relates to an optical network node design scheme in an ultra-dense wavelength division multiplexing passive optical network, in particular to an optical network node scheme based on uplink remodulation and homodyne coherent detection.
Background
In recent years, with the rapid development of broadband services, especially the explosive increase of data volume and network scale represented by services such as streaming media technology, high definition television, cloud computing, and the like, users have made urgent demands for large-scale, high-performance, and low-power-consumption access networks. The ultra-dense wavelength division multiplexing passive optical network (DWDM-PON) is considered as an optimal networking technology in the next-generation passive optical network, and has the advantages of transparent data transmission, high transmission bandwidth, network safety and the like. And the ultra-dense wavelength division multiplexing passive optical network (UDWDM-PON) further compresses the channel interval to enable the channel interval in the system to reach GHz level. However, the number of optical network nodes (ONUs) in the ultra-dense wavelength division multiplexing passive optical network is large, the cost of the ONUs determines the cost of the system to a large extent, and relative stability between uplink channels at a fine wavelength interval is difficult to guarantee, which restricts wide commercial use of the UDWDM-PON.
Currently, in a commercial optical fiber communication system, an amplitude keying method is widely used. Conventional optical detectors employ an intensity modulation/direct detection method, which, while simple and inexpensive, is limited in its sensitivity to optical detector and receiver front-end amplifier noise. For amplitude keying signals, the homodyne coherent detection technology can directly reduce the detection frequency to the baseband frequency without complex electric signal demodulation, and in addition, the receiving sensitivity of the receiving mode is also obviously higher than that of direct detection, the power budget of a system is increased, and the transmission distance is enlarged. However, homodyne coherent demodulation is not widely used in commercial systems due to the high price of the light source used to generate the required local oscillator.
An active filtering unit formed by the injection locking semiconductor laser can realize high-quality carrier recovery by reasonably configuring device parameters and the like. The recovered optical carriers correspond to the channel reference wavelengths generated in the optical line terminal one by one, and uplink data is modulated on the recovered optical carriers, so that the relative stability of an uplink channel is ensured while the spectrum utilization rate is improved. In addition, the optical carrier wave recovered by the carrier wave can be used as local oscillation light with low cost and high precision for homodyne coherent detection by considering the characteristics that the wavelength of the injection locking semiconductor laser is strictly aligned with the wavelength of the main laser and the phase is coherent with the main laser.
Disclosure of Invention
Aiming at the prior art, the invention provides a design scheme of an optical network node in an ultra-dense wavelength division multiplexing passive optical network, which not only uses the same wavelength to transmit uplink and downlink data, improves the spectrum utilization rate, and further improves the bearing capacity of a single PON; and the problem that the optical receiver needs to use a high-price local oscillator laser in the traditional coherent receiving scheme is solved by using the optical injection locking technology as the homodyne coherent detection technology, and the sensitivity of the optical receiver is improved. The invention has low cost and easy realization, and can be used as a large-scale laying scheme of the self-adaptive UDWDM-PON optical network node.
In order to solve the technical problem, the optical network node of the ultra-dense wavelength division multiplexing passive optical network provided by the invention comprises a 1 × 2n coupler, wherein n optical network nodes with the same structure are connected with the 1 × 2n coupler;
the optical network node comprises a first optical circulator, a first polarization controller, a second optical circulator, a distributed feedback laser, a first 1 x 2 coupler, a second polarization controller, a Mach-Zehnder modulator, a synthetic signal analyzer, a third polarization controller, an adjustable optical delay line, a second 1 x 2 coupler and a light detection device; 2 ports of the second optical circulator are connected with the distributed feedback type laser to realize an active filtering function; the first 1 x 2 coupler divides the optical carrier wave recovered by the active filtering into two paths which are respectively used as the optical carrier wave for uplink remodulation and local oscillator light required by homodyne coherent demodulation; the Mach-Zehnder modulator is connected with the synthesized signal analyzer, and the synthesized signal generator provides baseband signals of uplink data for the Mach-Zehnder modulator; the third polarization controller and the adjustable optical delay line respectively control the polarization state and the phase of the downlink data signal to adapt to homodyne coherent detection;
the first optical circulators and the third polarization controllers of the n optical network nodes are respectively connected with 2n output ports of the 1 x 2n coupler in a one-to-one correspondence manner;
in the communication process, the optical network node realizes the receiving of downlink user data and the sending of uplink user data; that is, each optical network node in the n optical network nodes comprises two channels respectively connected with 2 output ports of the 1 × 2n coupler, wherein the channel connected with the third polarization controller directly transmits multi-wavelength downlink user data transmitted from an optical line terminal; the channel connected with the first optical circulator realizes active filtering in a mode of optical injection locking, and the recovered optical carrier is divided into two paths; one path of the local oscillation light is used as local oscillation light required by homodyne coherent detection, and is coherently demodulated with downlink user data transmitted in a channel connected with the third polarization controller in an optical detection device, and the downlink user data corresponding to the local oscillation light is recovered; and the other path of modulation is used for modulating the uplink user data to finish uplink remodulation, thereby improving the channel utilization rate and ensuring the carrier synchronization of the uplink user.
The optical network node of the ultra-dense wavelength division multiplexing passive optical network of the invention is characterized in that each optical network node is respectively and independently connected with two output ports of the 1 x 2n coupler, and the connection relationship of each device in the optical network node is as follows:
2 ports of the first optical circulator are connected with one output port of the 1 x 2n coupler, 3 ports of the first optical circulator are connected to 1 port of the second optical circulator through the first polarization controller, and 3 ports of the second optical circulator are connected with an input port of the first 1 x 2 coupler; an output port of the first 1 × 2 coupler is connected with an optical input port of a mach-zehnder modulator through the second polarization controller, an electric drive port of the mach-zehnder modulator is connected to the synthesized signal analyzer, and an optical output port of the mach-zehnder modulator is connected with the 2 port of the first optical circulator;
an optical input port of the third polarization controller is connected with the other output port of the 1 × 2n coupler, and an optical output port of the third polarization controller is connected with one end of the adjustable optical delay line;
the other end of the adjustable light delay line and the other output port of the first 1 × 2 coupler are connected to the light detection device through a second 1 × 2 coupler.
Compared with the prior art, the invention has the beneficial effects that:
because the invention adopts the active filtering of the injection locking distribution feedback type laser, the optical carrier coherent with the corresponding wavelength is recovered during data receiving, on one hand, the optical carrier can be used as local oscillator light with low cost and recover data with a received signal through a homodyne coherent detection technology, on the other hand, the optical carrier can be used as the optical carrier of uplink data, the uplink data is transmitted through an uplink remodulation method, the utilization rate of a channel is further improved, the problem of relative wavelength drift between independent light sources is solved, and the wavelength synchronization of uplink users is ensured;
drawings
FIG. 1 is a schematic diagram of the optical network node structure of the ultra-dense wavelength division multiplexing passive optical network according to the present invention;
in the figure, the position of the upper end of the main shaft,
1-1 x 2n coupler 2-first optical circulator 3-first polarization controller
4-second optical circulator 5-distributed feedback laser 6-first 1 x 2 coupler
7-second polarization controller 8-Mach Zehnder modulator 9-synthetic signal analyzer
10-third polarization controller 11-tunable optical delay line 12-second 1 x 2 coupler
13-light detection means.
Detailed Description
The invention will be further described with reference to the following figures and specific examples, which are not intended to limit the invention in any way.
As shown in fig. 1, an optical network node of an ultra-dense wavelength division multiplexing passive optical network includes a 1 × 2n coupler 1, and n optical network nodes with the same structure are connected to the 1 × 2n coupler 1; the optical network node comprises a first optical circulator 2, a first polarization controller 3, a second optical circulator 4, a distributed feedback laser 5, a first 1 x 2 coupler 6, a second polarization controller 7, a Mach-Zehnder modulator 8, a synthesized signal analyzer 9, a third polarization controller 10, an adjustable optical delay line 11, a second 1 x 2 coupler 12 and a light detection device 13.
The first optical circulators 2 and the third polarization controllers 10 of the n optical network nodes are respectively connected with 2n output ports of the 1 × 2n coupler 1 in a one-to-one correspondence manner; that is, each optical network node is connected to two output ports of the 1 × 2n coupler 1 independently, and the connection relationship between the devices in the optical network node is as follows:
a port 2 of the first optical circulator 2 is connected with an output port of the 1 × 2n coupler 1, a port 3 of the first optical circulator 2 is connected to a port 1 of the second optical circulator 4 through the first polarization controller 3, and a port 3 of the second optical circulator 4 is connected with an input port of the first 1 × 2 coupler 6; a port 1 of the first 1 × 2 coupler 6 is connected to an optical input port of a mach-zehnder modulator 8 through the second polarization controller 7, an electric drive port of the mach-zehnder modulator 8 is connected to the synthesized signal analyzer 9, and an optical output port of the mach-zehnder modulator 8 is connected to a port 2 of the first optical circulator 2;
an optical input port of the third polarization controller 10 is connected to another output port of the 1 × 2n coupler 1, and an optical output port of the third polarization controller 10 is connected to one end of the tunable optical delay line 11;
the other end of the tunable optical delay line 11 and the other output port of the first 1 × 2 coupler 6 are connected to the optical detection device 13 through a second 1 × 2 coupler 12.
Wherein, 2 ports of the second optical circulator 4 are connected with the distributed feedback laser 5 to realize the active filtering function;
the first 1 × 2 coupler 6 divides the optical carrier recovered by active filtering into two paths, which are respectively used as the optical carrier for uplink remodulation and the local oscillator light required by homodyne coherent demodulation.
The mach-zehnder modulator 8 is connected to the synthesized signal analyzer 9, and the synthesized signal generator 9 provides a baseband signal of uplink data to the mach-zehnder modulator 8.
The third polarization controller 10 and the tunable optical delay line 11 respectively control the polarization state and the phase of the downlink data signal to adapt to homodyne coherent detection.
In the communication process, the optical network node realizes the receiving of downlink user data and the sending of uplink user data; the n optical network nodes have the same structure, and each optical network node comprises channels respectively connected with the 2 output ports of the 1 x 2n coupler; the channel connected with the third polarization controller directly transmits multi-wavelength downlink user data transmitted by the optical line terminal; the channel connected with the first optical circulator realizes active filtering in a mode of optical injection locking, and the recovered optical carrier is divided into two paths; one path of the local oscillation light is used as local oscillation light required by homodyne coherent detection, and is coherently demodulated with downlink user data transmitted in a channel connected with the third polarization controller in an optical detection device, and the downlink user data corresponding to the local oscillation light is recovered; and the other path of modulation is used for modulating the uplink user data to finish uplink remodulation, thereby improving the channel utilization rate and ensuring the carrier synchronization of the uplink user. The design scheme of the optical network node in the ultra-dense wavelength division multiplexing passive optical network is based on an optical injection locking technology and a homodyne coherent detection technology.
Example (b):
a design scheme of an ultra-dense wavelength division multiplexing passive optical network node is provided.
As shown in fig. 1, the optical network node includes one 1 × 2n coupler 1, n first optical circulators 2, n first polarization controllers 3, n second optical circulators 4, n distributed feedback lasers 5, n first 1 × 2 couplers 6, n second polarization controllers 7, n mach-zehnder modulators 8, a composite signal analyzer 9, n third polarization controllers 10, n adjustable optical delay lines 11, n second 1 × 2 couplers 12, and an optical detection device 13; dividing the signal into 2n channels from the 1 × 2n coupler 1, and respectively recording the channels as a 1 st channel to a 2 nd channel, wherein every two adjacent channels form a group, for example, the 1 st channel and the 2 nd channel form a group, the 3 rd channel and the 4 th channel form a group, and the like, and dividing the channels into n groups; the structure of each group of channels is the same, taking the 1 st channel and the 2 nd channel as an example, the 1 st channel comprises a first optical circulator 2, a first polarization controller 3, a second optical circulator 4 and a first 1 × 2 coupler 6; the 3 ports of the first optical circulator 2 are connected with a first polarization controller 3; 2 ports of the first optical circulator 2 are connected with the 1 x 2n coupler 1 to gather uplink user data; the port 1 of the second optical circulator 4 is connected with the first polarization controller 3; a port 2 of the second optical circulator 4 is connected with a distributed feedback laser 5 to realize active filtering, a port 3 of the second optical circulator 4 is connected with a first 1 multiplied by 2 coupler 6 to divide the recovered optical carrier into two paths, and one path comprises a second polarization controller 7 and a Mach-Zehnder modulator 8; the Mach-Zehnder modulator 8 is also connected with a synthetic signal analyzer 9; the synthesized signal analyzer 9 provides an uplink data baseband signal to the mach-zehnder modulator 8; the other path is directly connected with the second 1 multiplied by 2 coupler 12 to provide local oscillation light for homodyne coherent detection; the 2 nd channel comprises a third polarization controller 10 and an adjustable optical delay line 11; the third polarization controller 10 and the tunable optical delay line 11 respectively adjust the polarization state and the phase of the downlink data and then apply the optical carrier recovered by the active filtering to the second 1 × 2 coupler 12, and the second 1 × 2 coupler 12 is connected to the optical detection device 13 for receiving the downlink data.
In the invention, the optical network node realizes data receiving through a homodyne coherent detection technology, active filtering is realized through an injection locking distribution feedback type laser, and the recovered optical carrier can provide local oscillation light with low cost and high quality, and uplink remodulation is realized in the optical network node, so that the channel utilization rate is improved.
The working process of the optical network node design scheme in the ultra-dense wavelength division multiplexing passive optical network of the invention is as follows:
the method comprises the following steps: the optical network node divides the downlink user data into 2n paths through a 1 x 2n coupler 1, each two channels form a group, the structures of each group are the same, in each group of channels, active filtering is realized in one channel, and the downlink user data is transmitted in the other channel;
step two: the implementation of the active filtering is based on an injection locking distributed feedback laser 5, and technicians in the industry know how to output optical carriers with equal wavelength and coherent phase corresponding to downlink data one by reasonably designing device parameters and working parameters;
step three: in a channel for realizing active filtering in the optical network node, an optical carrier output by the active filtering is divided into two paths by the first 1 × 2 coupler 6, one path of the optical carrier is modulated by a baseband signal to be transmitted through the mach-zehnder modulator 8 and is connected with the 2 ports of the first optical circulator 2 to form complete uplink user data to enter an optical fiber for transmission; the other path of the local oscillator light is used as local oscillator light required by homodyne coherent demodulation and is connected with a second 1 multiplied by 2 coupler 12;
step four: another channel in the optical network node transmits the downlink user data, and is connected to the second 1 × 2 coupler 12 after the polarization state is adjusted by the third polarization controller 10 and the optical phase is adjusted by the adjustable optical delay line 11, and is coherently demodulated with the local oscillation light generated by the active filtering, and the downlink user data is recovered by the optical detection device 13.
In the invention, the optical network node adopts an active filtering mode of an injection locking semiconductor laser to ensure the discrimination between user data under a very small wavelength interval and provide low-cost and high-quality local oscillation light for homodyne coherent detection; the recovered optical carrier is used for modulating uplink data, so that the uplink data and the downlink data of each user are transmitted by adopting the same optical path, and the utilization rate of a channel is improved; and ensures the carrier synchronization of the uplink user; finally, the method provides green, efficient and high-speed broadband access service for users.
While the present invention has been described with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are illustrative only and not restrictive, and various modifications which do not depart from the spirit of the present invention and which are intended to be covered by the claims of the present invention may be made by those skilled in the art.
Claims (2)
1. An optical network node of an ultra-dense wavelength division multiplexing passive optical network comprises a 1 x 2n coupler (1), wherein n optical network nodes with the same structure are connected with the 1 x 2n coupler (1); the method is characterized in that:
the optical network node comprises a first optical circulator (2), a first polarization controller (3), a second optical circulator (4), a distributed feedback laser (5), a first 1 x 2 coupler (6), a second polarization controller (7), a Mach-Zehnder modulator (8), a synthetic signal analyzer (9), a third polarization controller (10), an adjustable optical delay line (11), a second 1 x 2 coupler (12) and a light detection device (13);
2 ports of the second optical circulator (4) are connected with the distributed feedback laser (5) to realize an active filtering function;
the first 1 x 2 coupler (6) divides the optical carrier recovered by active filtering into two paths which are respectively used as the optical carrier for uplink remodulation and local oscillator light required by homodyne coherent demodulation;
the Mach-Zehnder modulator (8) is connected with the synthesized signal analyzer (9), and the synthesized signal generator (9) provides a baseband signal of uplink data for the Mach-Zehnder modulator (8);
the third polarization controller (10) and the adjustable optical delay line (11) respectively control the polarization state and the phase of the downlink data signal to adapt to homodyne coherent detection;
the first optical circulators (2) and the third polarization controllers (10) of n optical network nodes are respectively connected with 2n output ports of the 1 × 2n coupler (1) in a one-to-one correspondence manner, each optical network node is respectively and independently connected with two output ports of the 1 × 2n coupler (1), wherein 2 ports of the first optical circulators (2) are connected with one output port of the 1 × 2n coupler (1), and an optical input port of the third polarization controller (10) is connected with the other output port of the 1 × 2n coupler (1);
in the communication process, the optical network node realizes the receiving of downlink user data and the sending of uplink user data; each optical network node in the n optical network nodes comprises two channels which are respectively connected with 2 output ports of the 1 x 2n coupler (1), wherein the channel connected with the third polarization controller (10) directly transmits multi-wavelength downlink user data transmitted by an optical line terminal; the channel connected with the first optical circulator (2) adopts an optical injection locking mode to realize active filtering, and the recovered optical carrier is divided into two paths; one path of the local oscillation light is used as local oscillation light required by homodyne coherent detection, and is coherently demodulated with downlink user data transmitted in a channel connected with the third polarization controller (10) in an optical detection device (13), and the downlink user data corresponding to the local oscillation light is recovered; and the other path of modulation is used for modulating the uplink user data to finish uplink remodulation, thereby improving the channel utilization rate and ensuring the carrier synchronization of the uplink user.
2. The optical network node of the ultra-dense wavelength division multiplexing passive optical network according to claim 1, wherein each optical network node is independently connected to two output ports of the 1 × 2n coupler (1), and the connection relationship between the devices in the optical network node is as follows:
2 ports of the first optical circulator (2) are connected with one output port of the 1 x 2n coupler (1), 3 ports of the first optical circulator (2) are connected to 1 port of the second optical circulator (4) through the first polarization controller (3), and 3 ports of the second optical circulator (4) are connected with an input port of the first 1 x 2 coupler (6); the output port of the first 1 x 2 coupler (6) is connected with the optical input port of a Mach-Zehnder modulator (8) through the second polarization controller (7), the electric drive port of the Mach-Zehnder modulator (8) is connected to the synthesized signal analyzer (9), and the optical output port of the Mach-Zehnder modulator (8) is connected with the 2 port of the first optical circulator (2);
an optical input port of the third polarization controller (10) is connected with the other output port of the 1 × 2n coupler (1), and an optical output port of the third polarization controller (10) is connected with one end of the tunable optical delay line (11);
the other end of the adjustable light delay line (11) and the other output port of the first 1 x 2 coupler (6) are connected to the light detection device (13) through a second 1 x 2 coupler (12).
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| CN104301811B (en) * | 2014-08-22 | 2018-01-02 | 武汉邮电科学研究院 | The sending, receiving method of relevant passive optical network and signal |
| US9634786B2 (en) * | 2015-02-13 | 2017-04-25 | Georgia Tech Research Corporation | Communication systems with phase-correlated orthogonally-polarized light-stream generator |
| CN107493149B (en) * | 2016-06-12 | 2019-03-01 | 天津大学 | Ultra dense wavelength division multiple passive optical network based on the whole network Wavelength synchronous |
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