Dual-polarization signal phase reconstruction method and system based on total blind polarization rotation matrix estimation

Abstract

The invention relates to the technical field of optical fiber communication, and discloses a dual-polarization signal phase reconstruction method and system based on total blind polarization rotation matrix estimation, and the method comprises the following specific steps: obtaining a to-be-measured dual-polarization signal; presetting a polarization rotation matrix parameter # imgabs0 #, and constructing an initial signal; preprocessing the initial signal; executing amplitude constraint operation on the preprocessed signal; implementing a dispersion compensation algorithm on the signal subjected to amplitude constraint to obtain phase information of a compensated phase signal; calculating an amplitude error between the signal without dispersion and the initial signal; combining the intensity of the dual-polarization signal to be measured and the phase information of the phase signal to obtain a phase reconstruction signal; iteratively optimizing the phase reconstruction signal to obtain a final phase reconstruction signal; and carrying out error rate calculation to approximately obtain a # imgabs 1 # value. The method solves the problem of low phase reconstruction precision caused by polarization rotation in the prior art, and has the characteristic of effectively avoiding polarization fading.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber communication technology, and more specifically, to a dual-polarization signal phase reconstruction method and system based on full-blind polarization rotation matrix estimation. Background Art

[0002] With the rapid development of the Internet of Things, cloud computing and artificial intelligence, data traffic is experiencing explosive growth. The huge demand for bandwidth and computing resources from these emerging technologies has driven the construction and technology upgrade of many large-scale data centers. In order to meet these growing demands, the development of high-speed and large-capacity data center optical interconnect technology has become a top priority.

[0003] For 400Gbit / s data center optical interconnects, intensity modulation direct detection (IMDD) technology has been widely adopted due to its simplicity and cost-effectiveness. However, in the face of the need to further increase communication rates, IMDD technology faces problems such as insufficient spectral efficiency, power selective fading caused by dispersion, and limitations in optical signal-to-noise ratio. These problems limit its application in coarse wavelength division multiplexing systems for 800Gbit / s or even 1.6Tbit / s optical interconnects within the range of 0 to 80 kilometers. Coherent optical communication systems can significantly increase transmission capacity and meet the above rate requirements by adopting high-order modulation formats and polarization multiplexing technology. However, this system has a complex structure, high power consumption and cost, which greatly limits its application in cost-sensitive data center optical interconnects.

[0004] In summary, how to invent a signal phase reconstruction method that can solve the problem of low phase reconstruction accuracy caused by polarization rotation in the prior art is a technical problem that urgently needs to be solved in this technical field. Summary of the invention

[0005] In order to solve the problem of low phase reconstruction accuracy caused by polarization rotation in the prior art, the present invention provides a dual-polarization signal phase reconstruction method and system based on full-blind polarization rotation matrix estimation, which has the characteristic of effectively avoiding polarization fading.

[0006] In order to achieve the above-mentioned purpose of the present invention, the technical scheme adopted is as follows: A dual-polarization signal phase reconstruction method based on full-blind polarization rotation matrix estimation includes the following specific steps: S1, obtaining a dual-polarization signal to be measured, wherein the dual-polarization signal includes a signal with added dispersion and a signal without added dispersion; by presetting a polarization rotation matrix parameter , and set an initial phase value for the signal without adding dispersion to construct the initial signal; S2, preprocessing initial signal; S3, using the amplitude information of the signal with added dispersion, performing an amplitude constraint operation on the preprocessed signal; S4, implementing a dispersion compensation algorithm on the amplitude-constrained signal to obtain phase information of a compensated phase signal; S5, calculating the amplitude error between the signal without dispersion addition and the initial signal; combining the intensity of the dual polarization signal to be measured and the phase information of the phase signal to obtain a phase reconstruction signal; S6. Iteratively optimize the phase reconstruction signal to obtain a final phase reconstruction signal.

[0007] Preferably, in step S1, by presetting a polarization rotation matrix parameter , and set an initial phase value for the signal without added dispersion to construct the initial signal. The specific steps are: Preset a polarization rotation matrix parameter , used for polarization multiplexing and polarization demultiplexing; parameters Set to:

[0008] in, is the polarization rotation matrix parameter The total number of values ​​of The larger the value of , the more accurate the estimation of the polarization rotation matrix; Calculate the RMS value of the signal without added dispersion in the two polarization states to obtain the initial signal amplitude , , and performing the same RMS calculation on the signal with added dispersion, we obtain the amplitude , ;in, , will be used to set the initial signal strength, and , Then it is reserved for the signal amplitude constraint in the subsequent steps; A randomly selected initial phase is assigned to the dual-polarization signals to be measured in two polarization states without additional dispersion, which serves as the start of signal processing:

[0009]

[0010] in , is the initial signal, , is a randomly selected initial phase, is the imaginary unit; at the same time, the current iteration counter is set to .

[0011] Furthermore, in step S2, the initial signal is preprocessed, and the specific steps are as follows: The accumulated dispersion effect of the initial signal during the optical fiber transmission is compensated; the compensated dispersion amount is recorded as 𝐶𝐷, which matches the total dispersion introduced by the optical fiber; the time domain expression of the compensation process is as follows:

[0012] in, Indicates the transmission distance when dispersion compensation is implemented in the optical fiber link; Indicates the time of signal propagation; represents the dispersion coefficient, which quantifies the degree of light pulse broadening in the optical fiber; Indicates the wavelength of the signal, which is related to the propagation characteristics of light in the medium; represents the speed of light; For the initial signal , The process of dispersion compensation is expressed as:

[0013]

[0014] The compensated signal , By its magnitude , and Phase , Composition, of which , represents the signal amplitude after fiber dispersion compensation, and , represents the corresponding signal phase; According to the preset polarization rotation matrix parameters Polarization demultiplexing is performed on the dispersion compensated signal, and the estimated polarization rotation matrix is ​​specifically:

[0015] Polarization demultiplexing is realized by the inverse matrix function of the polarization rotation matrix estimated by signal convolution; the current parameter value is , the dual polarization signals before polarization demultiplexing are expressed as , , then the demultiplexed signal , Specifically:

[0016]

[0017] The signal is processed in the frequency domain through a root raised cosine filter to achieve spectral constraints; Using the signal generated by mapping the independent data sequence, the pilot symbol is replaced by the signal at a specific position according to the predetermined proportion of the pilot symbol, so as to constrain the signal in the time domain; The signal after pilot constraint is processed again by a root raised cosine filter to perform spectrum constraint; Convolve the polarization rotation matrix with the pilot-constrained signal to perform polarization multiplexing:

[0018]

[0019] Additional dispersion is applied to the signal after the second spectrum constraint; the total amount of dispersion is ,in is the amount of dispersion introduced by the signal during transmission in the optical fiber link, and is the additional amount of dispersion added; the time domain impulse response of the dispersion addition operation is specifically:

[0020] in, It indicates the transmission distance when dispersion addition is implemented in the optical fiber link; Get the preprocessed signal:

[0021]

[0022] in, , represents the preprocessed signal, , represents the amplitude of the preprocessed signal, , Represents the phase of the preprocessed signal.

[0023] Furthermore, in step S3, the amplitude information of the signal with added dispersion is used to perform an amplitude constraint operation on the preprocessed signal, and the specific steps are as follows: Based on the amplitude information of the signal with added dispersion, the amplitude constraint is performed on the preprocessed signal, and the corresponding constrained signal is expressed as , express:

[0024] .

[0025] Furthermore, in step S4, a dispersion compensation algorithm is applied to the amplitude-constrained signal to obtain phase information of the compensated phase signal, and the specific steps are as follows: For amplitude-constrained signals Implement the dispersion compensation algorithm to obtain the phase information of the compensated phase signal:

[0026]

[0027] in , is the phase signal, , is the amplitude of the phase signal after dispersion compensation, , This is the phase of the signal at this time; By extracting the compensated signal , The phase angle of the signal is used to obtain the phase information of the signal:

[0028] .

[0029] Furthermore, in the step S5, the amplitude error between the signal without dispersion addition and the initial signal is calculated; the phase reconstruction signal is obtained by combining the intensity of the dual polarization signal to be measured and the phase information of the phase signal, and the specific steps are as follows: Quantify the amplitude difference between the dual polarization signal and the phase signal to be measured and evaluate the error between the two:

[0030] is the dual polarization signal to be measured without adding additional dispersion, Represents the calculated amplitude error, which is the error in the set time window Measurements are made within According to the amplitude of the test signal and the phase information of the phase signal, the phase reconstruction signal is obtained:

[0031]

[0032] in, , Reconstruct the signal for the resulting phase.

[0033] Furthermore, in step S6, the final signal is iteratively optimized to obtain the final phase reconstruction signal, and the specific steps are: Check the current iteration number Whether the preset maximum number of iterations has been reached ; If the current iteration number equal , that is, all iterations are completed, and the algorithm will output the final phase reconstruction signal ; If not equal to , indicating that the algorithm has not completed all scheduled iterations, then the amplitude error With the preset decision threshold Comparison between Less than or equal to the decision threshold ,Right now , the algorithm terminates and outputs the final signal; if the amplitude error Greater than the judgment threshold ,Right now , then the phase of the initial signal is updated to the phase of the phase-reconstructed signal, and the iteration counter is incremented The value of , returns to step S2 for iteration.

[0034] Furthermore, after obtaining the final phase reconstruction signal, the bit error rate of the final phase reconstruction signal is calculated, and the bit error rate is approximated to obtain value and confirm the accurate phase reconstruction signal. The specific steps are as follows: Determine polarization rotation matrix parameters The current value of ,like , then the current value number increases, if , then the current value number increases, and returns to step S1 until , and finally concluded bit error rate value; find The minimum value in the group BER data is used as the polarization rotation matrix Value, based on The values ​​confirm the accurate phase reconstruction signal.

[0035] A dual-polarization signal phase reconstruction system based on full-blind polarization rotation matrix estimation, comprising a signal generation module, a signal construction module, a preprocessing module, an amplitude constraint module, a dispersion compensation module, an error judgment module, an iterative optimization module, and a bit error rate calculation module; The signal generating module is used to obtain a dual-polarization signal to be measured, wherein the dual-polarization signal includes a signal with added dispersion and a signal without added dispersion; The signal construction module is used to preset a polarization rotation matrix parameter , and set an initial phase value for the signal without adding dispersion to construct the initial signal; The preprocessing module is used to preprocess the initial signal; The amplitude constraint module is used to perform an amplitude constraint operation on the preprocessed signal using the amplitude information of the signal with added dispersion; The dispersion compensation module is used to implement a dispersion compensation algorithm on the amplitude-constrained signal to obtain phase information of the compensated phase signal; The error judgment module is used to calculate the amplitude error between the signal without dispersion addition and the initial signal; combining the intensity of the dual polarization signal to be measured and the phase information of the phase signal to obtain a phase reconstruction signal; The iterative optimization module is used to iteratively optimize the phase reconstruction signal to obtain the final phase reconstruction signal.

[0036] Preferably, the signal generating module comprises a transmitter and a receiver; the transmitter comprises a laser, an I / Q modulator, and a digital-to-analog converter; the receiver comprises a polarization beam splitter, an optical splitter, a dispersion element, a photodetector, and an analog-to-digital converter; the transmitter and the receiver are connected via an optical fiber transmission link; The laser is used to generate an optical signal; the I / Q modulator is used to perform electro-optical conversion; the digital-to-analog converter is used to convert a digital signal into an analog signal; The polarization beam splitter is used to separate the received optical signal into two output light beams with orthogonal polarization states; the photodetector is used to convert the optical signal into an electrical signal; the dispersion element is used to introduce additional dispersion into one of the signals; and the analog-to-digital converter is used to convert the analog electrical signal into a digital signal.

[0037] The beneficial effects of the present invention are as follows: The present invention adopts phase reconstruction technology and polarization multiplexing technology based on signal strength information, and performs amplitude constraint operation on the preprocessed signal, implements dispersion compensation algorithm on the amplitude constrained signal, and calculates the amplitude error between the signal without dispersion added and the initial signal by using the amplitude information of the signal with added dispersion, and combines the intensity of the dual polarization signal to be measured and the phase information of the phase signal. Therefore, the present invention solves the problem of low phase reconstruction accuracy caused by polarization rotation in the prior art, and has the characteristic of effectively avoiding polarization fading. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a flow chart of a dual-polarization signal phase reconstruction method based on full-blind polarization rotation matrix estimation of the present invention.

[0039] Figure 2 It is a schematic diagram of a signal generation module of a dual-polarization signal phase reconstruction system based on full-blind polarization rotation matrix estimation of the present invention. DETAILED DESCRIPTION

[0040] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Example 1 like Figure 1 As shown, a dual-polarization signal phase reconstruction method based on full-blind polarization rotation matrix estimation includes the following specific steps: S1, obtaining a dual-polarization signal to be measured, wherein the dual-polarization signal includes a signal with added dispersion and a signal without added dispersion; by presetting a polarization rotation matrix parameter , and set an initial phase value for the signal without adding dispersion to construct the initial signal; at the same time, initialize the control parameters of the iterative process, including the current iteration counter, the error judgment threshold, and the preset maximum number of iterations; S2, preprocessing initial signal; S3, using the amplitude information of the signal with added dispersion, performing an amplitude constraint operation on the preprocessed signal; S4, implementing a dispersion compensation algorithm on the amplitude-constrained signal to obtain phase information of a compensated phase signal; S5, calculating the amplitude error between the signal without dispersion addition and the initial signal; combining the intensity of the dual polarization signal to be measured and the phase information of the phase signal to obtain a phase reconstruction signal; S6. Iteratively optimize the phase reconstruction signal to obtain a final phase reconstruction signal.

[0042] Example 2 More specifically, in a specific embodiment, in step S1, by presetting a polarization rotation matrix parameter , and set an initial phase value for the signal without added dispersion to construct the initial signal. The specific steps are: Preset a polarization rotation matrix parameter , used for polarization multiplexing and polarization demultiplexing; parameters Set to:

[0043] in, is the polarization rotation matrix parameter The total number of values ​​of The larger the value of , the more accurate the estimation of the polarization rotation matrix; Calculate the RMS value of the signal without added dispersion in the two polarization states to obtain the initial signal amplitude , , and performing the same RMS calculation on the signal with added dispersion, we obtain the amplitude , ;in, , will be used to set the initial signal strength, and , Then it is reserved for the signal amplitude constraint in the subsequent steps; A randomly selected initial phase is assigned to the dual-polarization signals to be measured in two polarization states without additional dispersion, which serves as the start of signal processing:

[0044]

[0045] in , is the initial signal, , is a randomly selected initial phase, is the imaginary unit; at the same time, the current iteration counter is set to .

[0046] In a specific embodiment, in step S2, the initial signal is preprocessed, and the specific steps are: The accumulated dispersion effect of the initial signal during the optical fiber transmission is compensated; the compensated dispersion amount is recorded as 𝐶𝐷, which matches the total dispersion introduced by the optical fiber; the time domain expression of the compensation process is as follows:

[0047] in, Indicates the transmission distance when dispersion compensation is implemented in the optical fiber link; Indicates the time of signal propagation; represents the dispersion coefficient, which quantifies the degree of light pulse broadening in the optical fiber; Indicates the wavelength of the signal, which is related to the propagation characteristics of light in the medium; represents the speed of light; For the initial signal , The process of dispersion compensation is expressed as:

[0048]

[0049] The compensated signal , By its magnitude , and Phase , Composition, of which , represents the signal amplitude after fiber dispersion compensation, and , represents the corresponding signal phase; According to the preset polarization rotation matrix parameters Polarization demultiplexing is performed on the dispersion compensated signal, and the estimated polarization rotation matrix is ​​specifically:

[0050] Polarization demultiplexing is realized by the inverse matrix function of the polarization rotation matrix estimated by signal convolution; the current parameter value is , the dual polarization signals before polarization demultiplexing are expressed as , , then the demultiplexed signal , Specifically:

[0051]

[0052] The signal is processed in the frequency domain through a root raised cosine filter to achieve spectral constraints; Using the signal generated by mapping the independent data sequence, the pilot symbol is replaced by the signal at a specific position according to the predetermined proportion of the pilot symbol, so as to constrain the signal in the time domain; The signal after pilot constraint is processed again by a root raised cosine filter to perform spectrum constraint; Convolve the polarization rotation matrix with the pilot-constrained signal to perform polarization multiplexing:

[0053]

[0054] Additional dispersion is applied to the signal after the second spectrum constraint; the total amount of dispersion is ,in is the amount of dispersion introduced by the signal during transmission in the optical fiber link, and is the additional amount of dispersion added; the time domain impulse response of the dispersion addition operation is specifically:

[0055] in, It indicates the transmission distance when dispersion addition is implemented in the optical fiber link; Get the preprocessed signal:

[0056]

[0057] in, , represents the preprocessed signal, , represents the amplitude of the preprocessed signal, , Represents the phase of the preprocessed signal.

[0058] In a specific embodiment, in step S3, the amplitude information of the signal with added dispersion is used to perform an amplitude constraint operation on the preprocessed signal, and the specific steps are: Based on the amplitude information of the signal with added dispersion, the amplitude constraint is performed on the preprocessed signal, and the corresponding constrained signal is expressed as , express:

[0059] .

[0060] In a specific embodiment, in step S4, a dispersion compensation algorithm is applied to the amplitude-constrained signal to obtain phase information of the compensated phase signal, and the specific steps are as follows: For amplitude-constrained signals Implement the dispersion compensation algorithm to obtain the phase information of the compensated phase signal:

[0061]

[0062] in , is the phase signal, , is the amplitude of the phase signal after dispersion compensation, , This is the phase of the signal at this time; By extracting the compensated signal , The phase angle of the signal is used to obtain the phase information of the signal:

[0063] .

[0064] In a specific embodiment, in the step S5, the amplitude error between the signal without dispersion addition and the initial signal is calculated; the phase reconstruction signal is obtained by combining the intensity of the dual polarization signal to be measured and the phase information of the phase signal, and the specific steps are: Quantify the amplitude difference between the dual polarization signal and the phase signal to be measured and evaluate the error between the two:

[0065] is the dual polarization signal to be measured without adding additional dispersion, Represents the calculated amplitude error, which is the error in the set time window Measurements are made within According to the amplitude of the test signal and the phase information of the phase signal, the phase reconstruction signal is obtained:

[0066]

[0067] in, , Reconstruct the signal for the resulting phase.

[0068] In a specific embodiment, in step S6, the final signal is iteratively optimized to obtain the final phase reconstruction signal, and the specific steps are: Check the current iteration number Whether the preset maximum number of iterations has been reached ; If the current iteration number equal , that is, all iterations are completed, and the algorithm will output the final phase reconstruction signal ; If not equal to , indicating that the algorithm has not completed all scheduled iterations, then the amplitude error With the preset decision threshold Comparison between Less than or equal to the decision threshold ,Right now , the algorithm terminates and outputs the final signal; if the amplitude error Greater than the judgment threshold ,Right now , then the phase of the initial signal is updated to the phase of the phase-reconstructed signal, and the iteration counter is incremented The value of , returns to step S2 for iteration.

[0069] In a specific embodiment, after obtaining the final phase reconstruction signal, the bit error rate of the final phase reconstruction signal is calculated, and the bit error rate is approximately obtained. value and confirm the accurate phase reconstruction signal. The specific steps are as follows: Determine polarization rotation matrix parameters The current value of ,like , then the current value number increases, if , then the current value number increases, and returns to step S1 until , and finally concluded bit error rate value; find The minimum value in the group BER data is used as the polarization rotation matrix Value, based on The values ​​confirm the accurate phase reconstruction signal.

[0070] Example 3 A dual-polarization signal phase reconstruction system based on full-blind polarization rotation matrix estimation, comprising a signal generation module, a signal construction module, a preprocessing module, an amplitude constraint module, a dispersion compensation module, an error judgment module, an iterative optimization module, and a bit error rate calculation module; The signal generating module is used to obtain a dual-polarization signal to be measured, wherein the dual-polarization signal includes a signal with added dispersion and a signal without added dispersion; The signal construction module is used to preset a polarization rotation matrix parameter , and set an initial phase value for the signal without adding dispersion to construct the initial signal; The preprocessing module is used to preprocess the initial signal; The amplitude constraint module is used to perform an amplitude constraint operation on the preprocessed signal using the amplitude information of the signal with added dispersion; The dispersion compensation module is used to implement a dispersion compensation algorithm on the amplitude-constrained signal to obtain phase information of the compensated phase signal; The error judgment module is used to calculate the amplitude error between the signal without dispersion addition and the initial signal; combining the intensity of the dual polarization signal to be measured and the phase information of the phase signal to obtain a phase reconstruction signal; The iterative optimization module is used to iteratively optimize the phase reconstruction signal to obtain the final phase reconstruction signal.

[0071] like Figure 2 As shown, the signal generating module includes a transmitter and a receiver; the transmitter includes a laser, an I / Q modulator, and a digital-to-analog converter; the receiver includes a polarization beam splitter, an optical splitter, a dispersion element, a photodetector, and an analog-to-digital converter; the transmitter and the receiver are connected via an optical fiber transmission link; The laser is used to generate a stable optical signal; the I / Q modulator is used to perform electro-optical conversion on the optical signal to achieve signal modulation; the digital-to-analog converter is used to convert the digital signal into the analog signal required for modulation in this process; In this embodiment, the I / Q modulator is specifically a dual-polarization I / Q modulator; the digital-to-analog converter is a 4-channel digital-to-analog converter DAC; The polarization beam splitter is used to separate the received optical signal into two output light beams with orthogonal polarization states; the photodetector is used to convert the optical signal into an electrical signal and capture the intensity information of the two signals; the dispersion element is used to introduce additional dispersion into one of the signals to facilitate phase reconstruction of the signal; the analog-to-digital converter is used to convert the analog electrical signal into a digital signal to provide data for subsequent digital signal processing.

[0072] In this embodiment, the received optical signal is separated into two output signal beams with orthogonal polarization states by a polarization beam splitter. , After that, the output signal beam is further , It is divided into two light beams, one of which is output through an analog-to-digital converter as a signal with added dispersion after adding dispersion, and the other signal is output through an analog-to-digital converter as a signal without added dispersion without adding dispersion, and the phases of the signal beams in these two polarization states are reconstructed respectively.

[0073] In this embodiment, in the optical fiber transmission link, the signal is transmitted through a standard single-mode optical fiber of 80 kilometers and passes through an erbium-doped optical fiber amplifier on the way. The function of the amplifier is to compensate for the energy loss of the signal during the transmission process in the optical fiber, ensuring that the signal still maintains sufficient strength after long-distance transmission.

[0074] In this embodiment, the present invention adopts a phase reconstruction technology and a phase modulation multiplexing (PDM) technology based on signal strength information.

[0075] Among them, phase reconstruction technology sends orthogonal amplitude modulation (QAM) signals at the transmitter and performs direct detection at the receiver, providing a potential solution for high-speed optical interconnection.

[0076] Polarization multiplexing (PDM) technology can double the transmission capacity of single-polarization optical transmission systems. In a carrier-assisted direct detection phase reconstruction receiver, the optical carrier will undergo random polarization rotation due to the transmission characteristics of the optical fiber link. When the polarization beam splitter (PBS) at the receiving end processes these rotated optical carriers, one of the orthogonal polarization states may be lost, and the polarization state signal information of one channel in the signal cannot be recovered. This phenomenon is called polarization fading. In contrast, the dual-polarization carrier-free phase reconstruction receiver obtains the intensity information of the two signals through two photodetectors and an additional dispersion element, and then uses the GS iterative algorithm to reconstruct the phase of the signal, and finally recovers the orthogonal amplitude modulation signal. Since there is no need to generate an optical carrier at the transmitting end, this method can effectively avoid the problem of polarization fading in theory.

[0077] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A dual-polarization signal phase reconstruction method based on full-blind polarization rotation matrix estimation, characterized in that: The specific steps include: S1, obtaining a dual-polarization signal to be measured, wherein the dual-polarization signal includes a signal with added dispersion and a signal without added dispersion; by presetting a polarization rotation matrix parameter , and set an initial phase value for the signal without adding dispersion to construct the initial signal; S2, preprocessing initial signal; S3, using the amplitude information of the signal with added dispersion, performing an amplitude constraint operation on the preprocessed signal; S4, implementing a dispersion compensation algorithm on the amplitude-constrained signal to obtain phase information of a compensated phase signal; S5, calculating the amplitude error between the signal without dispersion addition and the initial signal; combining the intensity of the dual polarization signal to be measured and the phase information of the phase signal to obtain a phase reconstruction signal; S6. Iteratively optimize the phase reconstruction signal to obtain a final phase reconstruction signal.

2. The dual-polarization signal phase reconstruction method based on full-blind polarization rotation matrix estimation according to claim 1, characterized in that: In the step S1, by presetting a polarization rotation matrix parameter , and set an initial phase value for the signal without added dispersion to construct the initial signal. The specific steps are: Preset a polarization rotation matrix parameter , used for polarization multiplexing and polarization demultiplexing; parameters Set to: in, is the polarization rotation matrix parameter The total number of values ​​of The larger the value of , the more accurate the estimation of the polarization rotation matrix; Calculate the RMS value of the signal without added dispersion in the two polarization states to obtain the initial signal amplitude , , and performing the same RMS calculation on the signal with added dispersion, we obtain the amplitude , ;in, , will be used to set the initial signal strength, and , Then it is reserved for the signal amplitude constraint in the subsequent steps; A randomly selected initial phase is assigned to the dual-polarization signals to be measured in two polarization states without additional dispersion, which serves as the start of signal processing: in , is the initial signal, , is a randomly selected initial phase, is the imaginary unit; at the same time, the current iteration counter is set to .

3. The dual-polarization signal phase reconstruction method based on full-blind polarization rotation matrix estimation according to claim 2, characterized in that: In the step S2, the initial signal is preprocessed, and the specific steps are: The accumulated dispersion effect of the initial signal during the optical fiber transmission is compensated; the compensated dispersion amount is recorded as 𝐶𝐷, which matches the total dispersion introduced by the optical fiber; the time domain expression of the compensation process is as follows: in, Indicates the transmission distance when dispersion compensation is implemented in the optical fiber link; Indicates the time of signal propagation; represents the dispersion coefficient, which quantifies the degree of light pulse broadening in the optical fiber; Indicates the wavelength of the signal, which is related to the propagation characteristics of light in the medium; represents the speed of light; For the initial signal , The process of dispersion compensation is expressed as: The compensated signal , By its magnitude , and Phase , Composition, of which , represents the signal amplitude after fiber dispersion compensation, and , represents the corresponding signal phase; According to the preset polarization rotation matrix parameters Polarization demultiplexing is performed on the dispersion compensated signal, and the estimated polarization rotation matrix is ​​specifically: Polarization demultiplexing is realized by the inverse matrix function of the polarization rotation matrix estimated by signal convolution; the current parameter value is , the dual polarization signals before polarization demultiplexing are expressed as , , then the demultiplexed signal , Specifically: The signal is processed in the frequency domain through a root raised cosine filter to achieve spectral constraints; Using the signal generated by mapping the independent data sequence, the pilot symbol is replaced by the signal at a specific position according to the predetermined proportion of the pilot symbol, so as to constrain the signal in the time domain; The signal after pilot constraint is processed again by a root raised cosine filter to perform spectrum constraint; Convolve the polarization rotation matrix with the pilot-constrained signal to perform polarization multiplexing: Additional dispersion is applied to the signal after the second spectrum constraint; the total amount of dispersion is ,in is the amount of dispersion introduced by the signal during transmission in the optical fiber link, and is the additional amount of dispersion added; the time domain impulse response of the dispersion addition operation is specifically: in, It indicates the transmission distance when dispersion addition is implemented in the optical fiber link; Get the preprocessed signal: in, , represents the preprocessed signal, , represents the amplitude of the preprocessed signal, , Represents the phase of the preprocessed signal.

4. The dual-polarization signal phase reconstruction method based on full-blind polarization rotation matrix estimation according to claim 3, characterized in that: In step S3, the amplitude information of the signal with added dispersion is used to perform an amplitude constraint operation on the preprocessed signal, and the specific steps are as follows: Based on the amplitude information of the signal with added dispersion, the amplitude constraint is performed on the preprocessed signal, and the corresponding constrained signal is expressed as , express: 。 5. The dual-polarization signal phase reconstruction method based on full-blind polarization rotation matrix estimation according to claim 4, characterized in that: In the step S4, a dispersion compensation algorithm is applied to the amplitude-constrained signal to obtain phase information of the compensated phase signal. The specific steps are as follows: For amplitude-constrained signals Implement the dispersion compensation algorithm to obtain the phase information of the compensated phase signal: in , is the phase signal, , is the amplitude of the phase signal after dispersion compensation, , This is the phase of the signal at this time; By extracting the compensated signal , The phase angle of the signal is used to obtain the phase information of the signal: 。 6. The dual-polarization signal phase reconstruction method based on full-blind polarization rotation matrix estimation according to claim 4, characterized in that: In the step S5, the amplitude error between the signal without dispersion addition and the initial signal is calculated; the phase reconstruction signal is obtained by combining the intensity of the dual polarization signal to be measured and the phase information of the phase signal. The specific steps are: Quantify the amplitude difference between the dual polarization signal and the phase signal to be measured and evaluate the error between the two: is the dual polarization signal to be measured without adding additional dispersion, Represents the calculated amplitude error, which is the error in the set time window Measurements are made within According to the amplitude of the test signal and the phase information of the phase signal, the phase reconstruction signal is obtained: in, , Reconstruct the signal for the resulting phase.

7. The dual-polarization signal phase reconstruction method based on full-blind polarization rotation matrix estimation according to claim 6, characterized in that: In step S6, the final signal is iteratively optimized to obtain the final phase reconstruction signal, and the specific steps are: Check the current iteration number Whether the preset maximum number of iterations has been reached ; If the current iteration number equal , that is, all iterations are completed, and the algorithm will output the final phase reconstruction signal ; If not equal to , indicating that the algorithm has not completed all scheduled iterations, then the amplitude error With the preset decision threshold Comparison between; if the amplitude error Less than or equal to the decision threshold ,Right now , the algorithm terminates and outputs the final signal; if the amplitude error Greater than the judgment threshold ,Right now , then the phase of the initial signal is updated to the phase of the phase reconstruction signal, and the iteration counter is incremented The value of , returns to step S2 for iteration.

8. The dual-polarization signal phase reconstruction method based on full-blind polarization rotation matrix estimation according to claim 7, characterized in that: After obtaining the final phase reconstruction signal, the bit error rate of the final phase reconstruction signal is calculated, and the bit error rate is approximated to obtain value and confirm the accurate phase reconstruction signal. The specific steps are as follows: Determine polarization rotation matrix parameters The current value of ,like , then the current value number increases, if , then the current value number increases, and returns to step S1 until , and finally concluded bit error rate value; find The minimum value in the group BER data is used as the polarization rotation matrix Value, based on The values ​​confirm the accurate phase reconstruction signal.

9. A dual-polarization signal phase reconstruction system based on fully blind polarization rotation matrix estimation, characterized in that: It includes a signal generation module, a signal construction module, a preprocessing module, an amplitude constraint module, a dispersion compensation module, an error judgment module, an iterative optimization module, and a bit error rate calculation module; The signal generating module is used to obtain a dual-polarization signal to be measured, wherein the dual-polarization signal includes a signal with added dispersion and a signal without added dispersion; The signal construction module is used to preset a polarization rotation matrix parameter , and set an initial phase value for the signal without adding dispersion to construct the initial signal; The preprocessing module is used to preprocess the initial signal; The amplitude constraint module is used to perform an amplitude constraint operation on the preprocessed signal using the amplitude information of the signal with added dispersion; The dispersion compensation module is used to implement a dispersion compensation algorithm on the amplitude-constrained signal to obtain phase information of the compensated phase signal; The error judgment module is used to calculate the amplitude error between the signal without dispersion addition and the initial signal; combining the intensity of the dual polarization signal to be measured and the phase information of the phase signal to obtain a phase reconstruction signal; The iterative optimization module is used to iteratively optimize the phase reconstruction signal to obtain the final phase reconstruction signal.

10. The dual-polarization signal phase reconstruction system based on full-blind polarization rotation matrix estimation according to claim 9, characterized in that: The signal generating module includes a transmitter and a receiver; the transmitter includes a laser, an I / Q modulator, and a digital-to-analog converter; the receiver includes a polarization beam splitter, an optical splitter, a dispersion element, a photodetector, and an analog-to-digital converter; The transmitter and receiver are connected via an optical fiber transmission link; The laser is used to generate an optical signal; the I / Q modulator is used to perform electro-optical conversion; the digital-to-analog converter is used to convert a digital signal into an analog signal; The polarization beam splitter is used to separate the received optical signal into two output light beams with orthogonal polarization states; the photodetector is used to convert the optical signal into an electrical signal; the dispersion element is used to introduce additional dispersion into one of the signals; and the analog-to-digital converter is used to convert the analog electrical signal into a digital signal.

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