Real-time closed-loop phase compensation system and method for optical fiber link and related device

Abstract

The embodiment of the invention discloses a real-time closed-loop phase compensation system and method for an optical fiber link and a related device. The system comprises a transmitting end and a receiving end. A transmitting end firstly divides an optical signal into two initial signals, one initial signal is reflected to obtain a reference signal, and the other initial signal is subjected to acousto-optic frequency shift processing and transmission of a target optical fiber link to obtain a received signal. And the receiving end carries out acousto-optic frequency shift, partial reflection and secondary acousto-optic frequency shift processing on the received signal, and sends the processed signal to the sending end through the target optical fiber link, so that the sending end carries out acousto-optic frequency shift processing on the signal again to obtain a feedback signal. A sending end performs beat frequency on a feedback signal and a reference signal to obtain a beat frequency signal, performs operation and step limitation on a phase error between the beat frequency signal and a radio frequency reference signal on the basis of a last compensation signal, and obtains a driving signal through a digital signal synthesizer to realize closed-loop phase compensation by using the driving signal. The method is simple in compensation and high in adaptability.

Description

Technical Field

[0001] This application relates to the technical field of signal processing, and particularly to a real-time closed-loop phase compensation system, method and related device for an optical fiber link. Background Art

[0002] In the process of high-precision optical fiber optical frequency transfer, environmental factors such as vibration noise and temperature change of the optical fiber link often cause large disturbances to the optical frequency phase, thus affecting the stability of the transfer process. In order to cope with these disturbances, it is necessary to precisely control the phase of the transmitted optical frequency to achieve real-time suppression of link noise and ensure high-stability transfer of the optical frequency phase.

[0003] However, traditional optical fiber optical frequency transfer technologies often use the accumulation of frequency increments over time to achieve phase control. Although this method can obtain a large phase control range and a fast response speed, it has certain mathematical complexity in practical applications. This method must calculate the frequency control amount and the action time according to the real-time phase error, and fine-tune the control parameters every time an adjustment is made, which makes this method less adaptable to environmental changes and the implementation process is more cumbersome.

[0004] Therefore, how to provide a simple and environmentally adaptable phase control method to achieve real-time suppression of disturbances and high-stability transfer of optical frequency phase in the process of high-precision optical fiber optical frequency transfer is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0005] Based on the above problems, this application provides a real-time closed-loop phase compensation system, method and related device for an optical fiber link to provide a simple and environmentally adaptable phase control method, and further achieve real-time suppression of disturbances and high-stability transfer of optical frequency phase in the process of high-precision optical fiber optical frequency transfer.

[0006] The embodiments of this application disclose the following technical solutions: A real-time closed-loop phase compensation system for an optical fiber link, the system includes: a transmitting end and a receiving end; the transmitting end is connected to the receiving end through a target optical fiber link; the transmitting end includes a beam splitter, a Faraday mirror, a first acousto-optic modulator, and a phase extraction and compensation unit; the receiving end includes a second acousto-optic modulator and a Faraday half-reflective and half-transmissive lens; the beam splitter is connected to the Faraday mirror; the beam splitter is also connected to the first acousto-optic modulator; the first acousto-optic modulator is connected to the second acousto-optic modulator through the target optical fiber link; the second acousto-optic modulator is connected to the Faraday half-reflective and half-transmissive lens; the beam splitter is connected to the phase extraction and compensation unit; the phase extraction and compensation unit is connected to the first acousto-optic modulator; The beam splitter is used to optically split the transmitted optical signal to obtain a first initial signal and a second initial signal; The Faraday mirror is used to optically reflect the first initial signal to obtain a reference signal; The first acousto-optic modulator is used to perform acousto-optic frequency shift on the second initial signal to obtain a first output signal; The target optical fiber link is used to transmit the first output signal to obtain a received signal; The second acousto-optic modulator is used to perform acousto-optic frequency shift on the received signal to obtain a modulated signal; The Faraday semi-reflective and semi-transmissive lens is used to perform partial reflection processing on the modulated signal to obtain the reflected signal, so that the second acousto-optic modulator, the target optical fiber link, and the first acousto-optic modulator perform acousto-optic frequency shift, signal transmission, and secondary acousto-optic frequency shift on the reflected signal in sequence to obtain a feedback signal; The beam splitter is further used to perform beat frequency on the feedback signal and the reference signal to obtain a beat frequency optical signal; The phase extraction and compensation unit is used to perform phase output step limitation and digital signal synthesis on the phase error of the beat frequency optical signal to obtain a driving signal, so as to perform phase compensation on the target optical fiber link through the first acousto-optic modulator by using the driving signal to form a real-time closed-loop compensation; the phase error of the beat frequency optical signal is calculated based on a radio frequency reference signal; the phase output step limitation is performed on the basis of the previous compensation signal.

[0007] In a possible implementation manner, the phase extraction and compensation unit includes: a photodetector, a phase error extraction module, a proportional operation module, a step output unit, and a direct digital synthesis unit; The beam splitter is connected to the photodetector; the phase error extraction module is respectively connected to the photodetector and the proportional operation module; the proportional operation module is connected to the step output unit; the step output unit is connected to the direct digital synthesis unit; The photodetector is used to perform photoelectric demodulation on the beat frequency optical signal to obtain a radio frequency signal; The phase error extraction module is used to calculate the error between the radio frequency signal and the radio frequency reference signal to obtain a phase error signal; The proportional operation module is used to perform proportional operation on the phase error signal to obtain a phase compensation amount; The step output unit is used to perform the phase output step limitation on the phase compensation amount to obtain a compensation signal; The direct digital synthesis unit is used to perform the digital signal synthesis on the compensation signal to obtain the driving signal.

[0008] In a possible implementation, the step output unit is specifically configured to: Calculate the target phase step. Combine the target phase step and the phase output step limit formula to perform phase output step limit on the phase compensation amount to obtain a compensation signal. Wherein, the phase output step limit formula is Pci = Pc(i - 1)+ΔP, Pci is the compensation signal; Pc(i - 1) is the previous compensation signal; ΔP is the phase control increment, when i is less than n, ΔP = ±|Pstep|, when i is equal to n, ΔP = ±(|Pc|-|Pstep|×(n - 1)); i is the step output ordinal number, i is a positive integer; n is the number of step outputs, n = ⌊|Pc| / |Pstep|⌋ + 1; Pc is the phase compensation amount; Pstep is the target phase step, Pstep = πfout / fsys, fout is the output frequency of the direct digital synthesis unit, and fsys is the system clock of the direct digital synthesis unit.

[0009] In a possible implementation, the Faraday half - reflecting and half - transmitting lens is further configured to: Perform partial transmission processing on the modulation signal to obtain a second output signal. Wherein, after phase compensation of the target optical fiber link, the system generates a new second output signal based on the transmitted optical signal for output.

[0010] A real - time closed - loop phase compensation method for an optical fiber link, the method includes: Optically split the transmitted optical signal to obtain a first initial signal and a second initial signal, and optically reflect the first initial signal to obtain a reference signal. Perform acousto - optic frequency shift on the second initial signal to obtain a first output signal, and transmit the first output signal through a target optical fiber link to obtain a received signal. Perform acousto - optic frequency shift on the received signal to obtain a modulation signal. Perform partial reflection processing on the modulation signal to obtain a reflection signal. Perform secondary signal transmission on the reflection signal through the target optical fiber link, and perform acousto - optic frequency shift on the reflection signal after secondary transmission through the target optical fiber link to obtain a feedback signal. Perform beat frequency on the feedback signal and the reference signal to obtain a beat - frequency optical signal, and perform phase output step limit and digital signal synthesis on the phase error of the beat - frequency optical signal to obtain a drive signal; the phase error of the beat - frequency optical signal is calculated based on a radio - frequency reference signal; the phase output step limit is performed on the basis of the previous compensation signal for phase limit. Use the drive signal to perform phase compensation on the target optical fiber link to form real-time closed-loop compensation.

[0011] In a possible implementation, the obtaining of the drive signal by performing phase output step limitation and digital signal synthesis on the phase error of the beat optical signal includes: Perform optoelectronic demodulation on the beat optical signal to obtain a radio frequency signal; Calculate the error between the radio frequency signal and the radio frequency reference signal to obtain a phase error signal; Perform proportional operation on the phase error signal to obtain a phase compensation amount; Perform the phase output step limitation on the phase compensation amount to obtain a compensation signal; Perform the digital signal synthesis on the compensation signal to obtain the drive signal.

[0012] In a possible implementation, the performing of the phase output step limitation on the phase compensation amount to obtain a compensation signal includes: Calculate the target phase step; Combine the target phase step and the phase output step limitation formula to perform the phase output step limitation on the phase compensation amount to obtain a compensation signal; Wherein, the phase output step limitation formula is Pci = Pc(i - 1)+△P, Pci is the compensation signal; Pc(i - 1) is the previous compensation signal; △P is the phase control increment, when i is less than n, △P = ±|Pstep|, when i is equal to n, △P = ±(|Pc|-|Pstep|×(n - 1)); i is the step output ordinal number, i is a positive integer; n is the step output number, n = ⌊|Pc| / |Pstep|⌋ + 1; Pc is the phase compensation amount; Pstep is the target phase step, Pstep = πfout / fsys, fout is the output frequency of the direct digital synthesis unit, fsys is the system clock of the direct digital synthesis unit.

[0013] In a possible implementation, the method further includes: Perform partial transmission processing on the modulation signal to obtain a second output signal; Wherein, after phase compensation is performed on the target optical fiber link, a new second output signal is generated based on the transmitted optical signal for output.

[0014] A real-time closed-loop phase compensation device for an optical fiber link, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, when the processor executes the computer program, the real-time closed-loop phase compensation method for the optical fiber link as described above is implemented.

[0015] A computer-readable storage medium stores instructions, which, when run on a terminal device, cause the terminal device to execute the real-time closed-loop phase compensation method for an optical fiber link as described above.

[0016] Compared with the prior art, the present application has the following beneficial effects: The real-time closed-loop phase compensation system for an optical fiber link provided by the present application includes a transmitting end and a receiving end in the system, and the transmitting end and the receiving end are connected through a target optical fiber link. The transmitting end includes a beam splitter, a Faraday mirror, a first acousto-optic modulator, and a phase extraction and compensation unit. The receiving end includes a second acousto-optic modulator and a Faraday semi-transmissive and semi-reflective lens. First, the beam splitter divides the transmitted optical signal into two paths, namely the first and second parts of the initial signal. The Faraday mirror reflects the first part of the signal to obtain a reference signal. The first acousto-optic modulator frequency-shifts the second part of the signal and transmits it to the receiving end through the target optical fiber link. The second acousto-optic modulator first performs acousto-optic frequency shift on the received signal to obtain a modulated signal, and then the Faraday semi-transmissive and semi-reflective lens performs partial reflection processing on the modulated signal to obtain a reflected signal, so as to use the second acousto-optic modulator, the target optical fiber link, and the first acousto-optic modulator to perform acousto-optic frequency shift, signal transmission, and secondary acousto-optic frequency shift on the reflected signal in sequence, thereby generating a feedback signal. The beam splitter performs beat frequency between the feedback signal and the reference signal to generate a beat-frequency optical signal, and then the phase extraction and compensation unit performs phase output step limitation and digital signal synthesis based on the phase error of the beat-frequency optical signal on the basis of the previous compensation signal to obtain a drive signal, and performs real-time phase compensation on the target optical fiber link through the acousto-optic modulator to form a closed-loop compensation. The present application uses digital signal synthesis technology to realize the phase compensation of the optical fiber link, so that only one proportional link can complete effective noise suppression. There is no need for fine debugging according to the actual link conditions, and the environmental adaptability is strong. At the same time, the present application breaks through the phase dynamic range limitation of one cycle by restricting the phase output step of the radio frequency signal and accumulating the phase shift amount (that is, realizing phase output step limitation on the basis of the previous compensation signal), realizes phase shift in a theoretically infinite range of positive and negative, and realizes efficient suppression of link noise in a large range. Description of the Drawings

[0017] To more clearly illustrate the technical solutions in the embodiments or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1Schematic diagram of the structure of a real-time closed-loop phase compensation system for an optical fiber link provided by an embodiment of the present application; Figure 2 Schematic diagram of the structure of another real-time closed-loop phase compensation system for an optical fiber link provided by an embodiment of the present application; Figure 3 Flowchart of a real-time closed-loop phase compensation method for an optical fiber link provided by an embodiment of the present application; Figure 4 Method flowchart of a driving signal synthesis method provided by an embodiment of the present application. Detailed implementation manners

[0019] To facilitate the understanding of the technical solutions provided by the embodiments of the present application, the background technologies related to the embodiments of the present application will be described first below.

[0020] In the process of high-precision optical fiber optical frequency transfer, factors such as vibration noise and temperature change of the on-site optical fiber link will cause large disturbances in the optical frequency phase. To achieve high-stability transfer of the optical frequency phase, it is necessary to control the emitted optical frequency phase to complete the real-time suppression of link noise. In traditional optical fiber optical frequency transfer technologies, the accumulation of frequency increments in time is mostly used to achieve phase control. Although this method can obtain a sufficiently large phase control range and response speed by changing the frequency, its implementation process is relatively complex. Specifically, it is necessary to calculate the frequency control amount and action time according to the phase error, which involves complex mathematical relationships, and it is necessary to finely adjust the control parameters according to the actual situation during the implementation process, resulting in poor environmental adaptability.

[0021] In addition, traditional phase control methods, such as phase shifters and delay lines, usually have the limitation of a small control range and are difficult to meet the requirements of high-precision optical fiber optical frequency transfer.

[0022] To solve this problem, an embodiment of the present application provides a real-time closed-loop phase compensation system for an optical fiber link. The system includes a beam splitter, a Faraday mirror, a target optical fiber link, a first acousto-optic modulator, a second acousto-optic modulator, a Faraday semi-transparent and semi-reflective lens, and a phase extraction and compensation unit. The beam splitter first divides the transmitted optical signal into two beams: a first initial signal and a second initial signal. The Faraday mirror reflects the first initial signal to generate a reference signal. The first acousto-optic modulator performs acousto-optic modulation on the second initial signal to change its frequency and generate a first output signal. These modulated optical signals are transmitted through the target optical fiber link to obtain a received signal. The second acousto-optic modulator first performs acousto-optic frequency shift on the received signal to obtain a modulated signal, and then the Faraday semi-transparent and semi-reflective lens performs partial reflection processing on the modulated signal to obtain a reflected signal, so that the second acousto-optic modulator, the target optical fiber link, and the first acousto-optic modulator perform acousto-optic frequency shift, signal transmission, and secondary acousto-optic frequency shift on the reflected signal in sequence to obtain a feedback signal. The beam splitter performs beat frequency processing on the feedback signal and the reference signal to obtain a beat frequency optical signal for detecting the phase difference. The phase extraction and compensation unit outputs a drive signal according to the phase error detected by the beat frequency optical signal, and performs real-time phase compensation on the target optical fiber link through the first acousto-optic modulator. This process is closed-loop, that is, the compensation amount is continuously adjusted according to the feedback signal to ensure that the phase of the signal is always corrected during transmission. The present application uses digital signal synthesis technology to achieve phase compensation for the optical fiber link, and can complete efficient noise suppression through a proportional link, avoiding the complex operations of fine debugging according to the actual link conditions in the traditional method. In addition, the system has strong environmental adaptability, can automatically adapt to different environmental changes, and ensure stable phase compensation. By restricting the phase output step of the radio frequency signal and accumulating the phase shift amount (that is, realizing the phase output step restriction based on the previous compensation signal), the present application breaks through the limitation of the phase dynamic range of one cycle in the traditional method, and theoretically realizes phase shift in the range of positive and negative infinity, so as to efficiently suppress the large-amplitude noise in the link, and significantly improve the stability and noise suppression effect of the system. The limitation is difficult to meet the requirements of high-precision optical fiber optical frequency transfer. Its control range is limited, and it is difficult to effectively cope with the large phase changes caused by environmental interference during high-precision transfer, so the effect in practical applications is not ideal.

[0023] To solve this problem, an embodiment of the present application provides a real-time closed-loop phase compensation system for an optical fiber link. The system includes a beam splitter, a Faraday mirror, a target optical fiber link, a first acousto-optic modulator, a second acousto-optic modulator, a Faraday half-reflecting and half-transmitting lens, and a phase extraction and compensation unit. The beam splitter first divides the transmitted optical signal into two beams: a first initial signal and a second initial signal. The Faraday mirror reflects the first initial signal to generate a reference signal. The first acousto-optic modulator performs acousto-optic modulation on the second initial signal to change its frequency and generate a first output signal. These modulated optical signals are transmitted through the target optical fiber link to obtain a received signal. The second acousto-optic modulator and the Faraday half-reflecting and half-transmitting lens perform partial reflection processing on the received signal to generate a reflected signal, and the reflected signal is fed back to the first output signal through the second acousto-optic modulator and the target optical fiber link for acousto-optic frequency shift again, thereby generating a feedback signal. The beam splitter performs beat frequency processing on the feedback signal and the reference signal to obtain a beat frequency optical signal for detecting the phase difference. The phase extraction and compensation unit outputs a drive signal according to the phase error detected by the beat frequency optical signal, and performs real-time phase compensation on the target optical fiber link through the first acousto-optic modulator. This process is closed-loop, that is, the compensation amount is continuously adjusted according to the feedback signal to ensure that the phase of the signal is always corrected during transmission. The present application uses digital signal synthesis technology to achieve phase compensation for the optical fiber link, and can complete efficient noise suppression through a proportional link, avoiding the complex operations of fine debugging according to the actual link conditions in the traditional method. In addition, the system has strong environmental adaptability and can automatically adapt to different environmental changes to ensure stable phase compensation. By restricting the phase output step of the radio frequency signal and accumulating the phase shift amount (that is, realizing the phase output step limit based on the previous compensation signal), the present application breaks through the phase dynamic range limit of one cycle in the traditional method, and theoretically realizes phase shift in the range of positive and negative infinity, so as to efficiently suppress large-amplitude noise in the link and significantly improve the stability and noise suppression effect of the system.

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0025] See Figure 1 , which is a schematic structural diagram of a real-time closed-loop phase compensation system for an optical fiber link provided by an embodiment of the present application. As Figure 1As shown, the system includes a transmitting end and a receiving end, and the transmitting end is connected to the receiving end through a target optical fiber link. The transmitting end includes a beam splitter, a Faraday mirror, a target optical fiber link, a first acousto-optic modulator, and a phase extraction and compensation unit. The receiving end includes a second acousto-optic modulator and a Faraday semi-transparent and semi-reflective lens.

[0026] The transmitting end includes a beam splitter, a Faraday mirror, a target optical fiber link, a first acousto-optic modulator, and a phase extraction and compensation unit.

[0027] 1. Beam splitter: Function: The beam splitter is an optical element. One of its functions is to split the incident optical signal into two beams, respectively called the "first initial signal" and the "second initial signal". These beam splitters are often used to separate optical signals for subsequent processing. Another function of the beam splitter is to perform beat frequency processing on the feedback signal and the reference signal to obtain a beat frequency optical signal. Through beat frequency, a low-frequency signal can be generated, which contains the phase difference information between the two optical signals.

[0028] Connection with other components: (1) Connection with the Faraday mirror: Transmit the first initial signal generated by the beam splitter to the Faraday mirror.

[0029] (2) Connection with the first acousto-optic modulator: Transmit the second initial signal to the first acousto-optic modulator.

[0030] 2. Faraday mirror: Function: The Faraday mirror reflects the input first initial signal and generates a reference signal. This signal will be compared with other signals in subsequent steps to help determine the phase error.

[0031] Connection with other components: (1) Connection with the beam splitter: Reflect the light from the beam splitter to obtain a reference signal and perform beat frequency processing on the reference signal.

[0032] 3. First acousto-optic modulator: Function: This device modulates the input second initial signal through the acousto-optic effect, that is, changes its frequency. The modulated signal is called the first output signal. The main function of this device is to shift the frequency of the optical signal.

[0033] Connection with other components: (1) Connection with the beam splitter: Receive the second initial signal from the beam splitter and perform modulation.

[0034] (2) Connection with the target optical fiber link: Transmit the modulated optical signal through the optical fiber link.

[0035] (3) Connect to the receiving end via an optical fiber link: The receiving end receives the modulated optical signal through this link.

[0036] (4) Connect to the phase extraction and compensation unit: The feedback signal is compensated for phase in real time through the phase extraction and compensation unit to ensure stable signal transmission in the link.

[0037] 4. Target optical fiber link: Function: The target optical fiber link is used to transmit the modulated optical signal and the partially reflected optical signal, i.e., the first output signal and the reflected signal. It transmits the signal from the optical module to the receiving end through the optical fiber and can also transmit the signal from the receiving end to the optical module through the optical fiber.

[0038] Connection to other components: (1) Connect to the receiving end through the first acousto-optic modulator: The target optical fiber link receives the first output signal generated by the first acousto-optic modulator and transmits it to the receiving end. The target optical fiber link can also receive the reflected signal generated by the receiving end and transmit it to the first acousto-optic modulator.

[0039] 5. Phase extraction and compensation unit: Function: The phase extraction and compensation unit processes the phase error of the beat optical signal and outputs a drive signal. This drive signal is used to adjust the phase in the system to ensure the stability of the signal during transmission.

[0040] Phase output step limit: This process performs step limit based on the previous phase compensation value, so that the system compensation will not be over-adjusted, thus ensuring the stability and controllability of the real-time adjustment process.

[0041] Connection to other components: (1) Connect to the beam splitter: Receive the beat optical signal transmitted by the beam splitter and compensate for the phase error.

[0042] (2) Connect to the first acousto-optic modulator: Adjust the phase of the optical signal according to the drive signal to ensure that the signal transmission in the optical fiber link is not affected by the phase error.

[0043] The purpose of the entire system is to ensure accurate signal transmission by dynamically detecting and compensating for the phase error in the optical signal. The process is as follows: Signal splitting and modulation: The beam splitter splits the incident optical signal into two beams, which are processed by the Faraday mirror and the first acousto-optic modulator respectively. The Faraday mirror reflects one of the optical signals, while the first acousto-optic modulator performs frequency shifting on the other optical signal.

[0044] Signal Transmission and Reception: The modulated optical signal is transmitted through the target optical fiber link and partially reflected at the receiving end. The reflected signal is transmitted and modulated, and finally becomes the feedback signal.

[0045] Phase Detection and Compensation: The beam splitter performs beat frequency on the feedback signal and the reflected signal, and transmits the beat frequency signal to the phase extraction and compensation unit. The phase extraction and compensation unit generates a driving signal step by step by calculating the error between the beat frequency signal and the RF reference signal, so as to correct the phase of the signal in real time through the driving signal and ensure the stable transmission of the optical signal.

[0046] Closed-loop Feedback: This process is closed-loop, and the system automatically adjusts according to the phase error each time to ensure the stability and efficiency of signal transmission.

[0047] The receiving end includes a second acousto-optic modulator and a Faraday half-reflecting and half-transmitting lens.

[0048] 1. Second Acousto-optic Modulator (Second Modulator): Function: The second acousto-optic modulator is mainly used to perform acousto-optic frequency shift on the received signal to obtain a modulated signal. Simply put, it changes the frequency of the incident optical signal through the acousto-optic effect, thereby realizing the modulation of the optical signal.

[0049] Connection with Other Components: (1) Connection with the Target Optical Fiber Link: The first acousto-optic modulator transmits the signal to the receiving end through the target optical fiber link.

[0050] (2) Connection with the Faraday Half-reflecting and Half-transmitting Lens: The second acousto-optic modulator is connected to the Faraday half-reflecting and half-transmitting lens. The optical signal modulated by the second acousto-optic modulator will be transmitted to the Faraday half-reflecting and half-transmitting lens, which partially reflects the signal.

[0051] 2. Faraday Half-reflecting and Half-transmitting Lens: Function: The Faraday half-reflecting and half-transmitting lens is a special optical element with the properties of partial reflection and partial transmission. When the modulated signal passes through it, part of the optical signal will be reflected to become the reflected signal, while the rest will pass through. The reflected part is the feedback signal of the system, and this signal will be returned to the system after a series of processes.

[0052] Connection with Other Components: (1) Connection with the Second Acousto-optic Modulator: It receives the optical signal processed by the second acousto-optic modulator.

[0053] (2) Connection with the Target Optical Fiber Link: The reflected signal will be transmitted to the first acousto-optic modulator through the target optical fiber link.

[0054] (3) Connect to the first acousto-optic modulator: Through the target optical fiber link, the signal will finally be transmitted to the first acousto-optic modulator for secondary processing.

[0055] The following is the function flow of the receiving end in the entire signal transmission, involving the second acousto-optic modulator, the Faraday half-reflective and half-transmissive lens, the first acousto-optic modulator, and the target optical fiber link: (1) Operation of the second acousto-optic modulator: First, the received signal from the target optical fiber link enters the second acousto-optic modulator. This modulator uses the acousto-optic effect to shift the frequency of the signal, obtaining a modulated signal. This process is similar to changing the frequency of the optical signal to make it suitable for subsequent transmission and reflection processing.

[0056] (2) Reflection and transmission of the Faraday half-reflective and half-transmissive lens: After passing through the second acousto-optic modulator, the modulated signal enters the Faraday half-reflective and half-transmissive lens. At the Faraday half-reflective and half-transmissive lens, the signal will be partially reflected to form a reflected signal, and the other part will pass through the mirror surface. This reflected signal will become the feedback signal in the system.

[0057] The reflected signal will be transmitted through the target optical fiber link and continue to be transmitted in the system.

[0058] (3) Transmission and modulation of the feedback signal: The reflected signal enters the target optical fiber link, is transmitted through this link to the first acousto-optic modulator for further frequency shift processing. After this process, the signal will be transmitted back to the target optical fiber link again and then enter the second acousto-optic modulator for secondary processing, thus ensuring that the entire signal undergoes a series of modulation, transmission, and feedback steps.

[0059] (4) Generation of the feedback signal: After one acousto-optic frequency shift (the second acousto-optic modulator), one signal transmission (the target optical fiber link), and two acousto-optic frequency shifts (the first acousto-optic modulator), the feedback signal required by the system is finally generated. This feedback signal contains the information processed by each component in the system, especially the changes in phase and frequency.

[0060] The feedback mechanism and signal processing in this process play a crucial role in the entire system, providing a key reference for subsequent phase compensation and adjustment.

[0061] In a possible implementation, the Faraday half-reflective and half-transmissive lens is also used for: Performing partial transmission processing on the modulated signal to obtain a second output signal; wherein, after phase compensation in the target optical fiber link, the system generates a new second output signal based on the transmitted optical signal for output.

[0062] Specifically, the receiving end can also partially transmit the received modulated signal to obtain a second output signal. Meanwhile, during the transmission process, the phase of the optical signal is compensated to restore its accuracy. Finally, based on the phase-compensated signal, the system can generate a new second output signal (i.e., the compensated and stable second output signal) and output it.

[0063] See Figure 2 , Figure 2 FIG. is a schematic structural diagram of another real-time closed-loop phase compensation system for an optical fiber link provided by an embodiment of the present application. Specifically, the phase extraction and compensation unit includes: a photodetector, a phase error extraction module (such as a phase comparator), a proportional operation module, a step output unit, and a direct digital synthesis unit. The beam splitter is connected to the photodetector; the phase error extraction module is respectively connected to the photodetector and the proportional operation module; the proportional operation module is connected to the step output unit; the step output unit is connected to the direct digital synthesis unit.

[0064] Photodetector: The photodetector is mainly used to convert an optical signal into an electrical signal. In this system, its function is to perform optical demodulation on the beat optical signal to obtain a radio frequency signal. The radio frequency signal is a type of electrical signal, usually used to process and analyze the frequency components of the signal.

[0065] Beam splitter: The beam splitter is used to generate a beat optical signal, which is an optical signal with a specific frequency. It is connected to the photodetector to ensure that the photodetector can receive the beat optical signal and perform demodulation.

[0066] Phase error extraction module: The function of this module is to calculate the phase error between the radio frequency signal and the radio frequency reference signal, and extract the phase error signal Pe. The radio frequency reference signal is usually a predetermined standard signal, used to compare with the received signal to determine its phase difference.

[0067] Proportional operation module: This module is used to perform proportional operation on the phase error signal. Its goal is to convert the error into a phase compensation amount Pc through a certain proportional relationship (usually according to a certain algorithm or adjusting the proportional coefficient). This phase compensation amount is a correction to the original signal to ensure that the signal can be restored to the correct phase state.

[0068] Step output unit: The task of the step output unit is to perform step limitation on the calculated phase compensation amount Pc to obtain a compensation signal Pci, so as to ensure the accuracy and stability of the phase adjustment. Step limitation means that the change of the phase compensation amount is gradual to avoid unstable system caused by excessive adjustment.

[0069] Direct Digital Synthesis Unit: The function of this unit is to synthesize digital signals based on the compensation signals provided by the step output unit. The synthesized signal is a compensated signal that can correct the phase error of the original signal and ensure that the output signal has the correct phase characteristics.

[0070] In a possible implementation, the phase error signal Pe undergoes proportional operation through the proportional operation module to obtain the phase compensation amount Pc. The proportional coefficient of the proportional operation module is K, so Pc = K × Pe, where K is the proportional coefficient. Since the error amount is the sum of the noises of the round-trip link, the value of K can be, but is not limited to, 0.5.

[0071] In a possible implementation, the step output unit is specifically used for: Calculating the target phase step, and combining the target phase step with the phase output step limit formula to perform the phase output step limit on the phase compensation amount to obtain a compensation signal.

[0072] Among them, the phase output step limit formula is Pci = Pc(i - 1)+△P, where Pci is the compensation signal; Pc(i - 1) is the previous compensation signal; △P is the phase control increment. When i is less than n, △P = ±|Pstep|, and when i is equal to n, △P = ±(|Pc|-|Pstep|×(n - 1)); i is the step output ordinal number, and i is a positive integer; n is the number of step outputs, n = ⌊|Pc| / |Pstep|⌋+1; Pc is the phase compensation amount; Pstep is the target phase step, Pstep = πfout / fsys, where fout is the output frequency of the direct digital synthesis unit, and fsys is the system clock of the direct digital synthesis unit.

[0073] It should be noted that the positive or negative sign of △P depends on the direction of Pc. If the phase to be compensated needs to be advanced, it is positive, otherwise it is negative. n = ⌊|Pc| / |Pstep|⌋+1 means taking the floor of |Pc| / |Pstep| and then adding 1.

[0074] In a possible implementation, fout can be, but is not limited to, 50 MHz (megahertz), and fsys can be, but is not limited to, 500 MHz (megahertz). Therefore, Pstep = 0.1π.

[0075] Exemplarily, assuming Pc = 5.03π and Pstep = 0.1π, then n = 51.

[0076] In a possible implementation, the direct digital synthesis unit may be selected as, but not limited to, a direct digital synthesizer (DDS), or a digital-to-analog converter (DAC) driven by a field-programmable gate array (FPGA) chip.

[0077] A real-time closed-loop phase compensation system for an optical fiber link provided by this application realizes efficient compensation for the phase of the optical fiber link by adopting digital signal synthesis technology. This technology enables the system to effectively suppress noise with only one proportional link, without the need for cumbersome fine debugging according to the actual link conditions, and has good environmental adaptability. In addition, this application also breaks through the phase dynamic range limitation within a single period by restricting the phase output step of the radio frequency signal, that is, adjusting the phase based on the previous compensation signal. Through this method, the system can achieve theoretically infinite phase adjustment in both positive and negative directions, thereby realizing large-range and efficient suppression of link noise, and significantly improving the stability and signal quality of the optical fiber link.

[0078] See Figure 3 as shown Figure 3 is a flowchart of a real-time closed-loop phase compensation method for an optical fiber link provided by an embodiment of this application, including S301 - S306: S301: Optically split the transmitted optical signal to obtain a first initial signal and a second initial signal, and optically reflect the first initial signal to obtain a reference signal.

[0079] Optically split the transmitted optical signal to obtain two initial signals: a first initial signal and a second initial signal. Then, the first initial signal is reflected to obtain a reference signal. By splitting the optical signal into two parts, one part is used for subsequent reflection processing, and the other part is used for subsequent frequency shifting and transmission.

[0080] It should be noted that the input optical signal can be split into two beams by an optical splitter, and optical reflection is usually achieved through a mirror or a reflector.

[0081] S302: Acousto-optically shift the frequency of the second initial signal to obtain a first output signal, and transmit the first output signal through a target optical fiber link to obtain a received signal.

[0082] Perform acousto-optic frequency shift on the second initial signal to obtain a first output signal. Then, transmit this signal through the target optical fiber link to finally obtain a received signal. Frequency modulate the optical signal through the acousto-optic effect. This modulation can be used to control the frequency of the optical signal to ensure that important information is not lost due to transmission loss or phase error during signal transmission in the link.

[0083] S303: Perform acousto-optic frequency shift on the received signal to obtain a modulated signal.

[0084] Perform acousto-optic frequency shift on the received signal through an acousto-optic modulator to obtain a modulated signal, that is, change the frequency of the incident optical signal through the acousto-optic effect, thereby realizing the modulation of the optical signal.

[0085] S304: Perform partial reflection processing on the modulated signal to obtain a reflected signal.

[0086] Perform partial reflection processing on the modulated signal to obtain a reflected signal. Obtain feedback information through the reflected signal, and the reflected signal is used for subsequent phase correction and compensation.

[0087] S305: Perform secondary signal transmission on the reflected signal through the target optical fiber link, and perform acousto-optic frequency shift on the reflected signal that has undergone secondary transmission through the target optical fiber link to obtain a feedback signal.

[0088] Perform secondary signal transmission on the reflected signal through the target optical fiber link, and perform acousto-optic frequency shift on the transmitted signal to obtain a feedback signal. Perform secondary signal transmission to enhance the quality of the feedback signal, and modulate the signal through frequency shift to ensure that the feedback signal can effectively participate in the closed-loop control. The second transmission and frequency shift operations help to further improve the quality and stability of the signal, ensuring effective closed-loop control in the system.

[0089] S306: Perform beat frequency on the feedback signal and the reference signal to obtain a beat frequency optical signal, and perform phase output step limit and digital signal synthesis on the phase error of the beat frequency optical signal to obtain a drive signal.

[0090] Perform beat frequency processing on the feedback signal and the reference signal to obtain a beat frequency optical signal. Based on the previous compensation signal, perform phase output step limit and digital signal synthesis on the phase error of the beat frequency optical signal to obtain a drive signal. The beat frequency signal can reveal the phase difference between signals. By using digital signal processing methods to limit the phase error, a drive signal is generated to correct the phase deviation in the system.

[0091] The beat frequency technique generates a frequency difference through the interference of two optical signals, enabling the detection and analysis of the phase error between signals. Based on the previous compensation signal, the step limit and digital signal synthesis techniques can accumulate the phase shift amount and effectively correct and control the phase error.

[0092] See Figure 4 , Figure 4 FIG. is a flowchart of a method for synthesizing a driving signal provided by an embodiment of the present application. Correspondingly, the phase output step limit and digital signal synthesis of the phase error of the beat frequency optical signal in step S305 to obtain a driving signal can be specifically implemented through steps A1-A5: A1: Perform optoelectronic demodulation on the beat frequency optical signal to obtain a radio frequency signal.

[0093] To synthesize the driving signal, first, optoelectronic demodulation can be performed on the beat frequency optical signal to convert the optical signal into a radio frequency signal. The optoelectronic demodulation process can use a photodetector or a photodiode to convert the optical signal into a corresponding electrical signal (radio frequency signal).

[0094] Optoelectronic demodulation uses the photoelectric effect to convert the optical signal into an electrical signal. Specifically, the beat frequency optical signal is demodulated by a detector to generate a corresponding radio frequency signal, which can then be further processed and analyzed.

[0095] A2: Calculate the error between the radio frequency signal and the radio frequency reference signal to obtain a phase error signal.

[0096] Calculate the error between the radio frequency signal and the radio frequency reference signal to obtain a phase error signal. The radio frequency reference signal is usually a known standard signal representing the ideal reference phase in the system.

[0097] By comparing the radio frequency signal and the reference signal, the phase difference between them can be obtained. Usually, a phase comparator is used to calculate the error between the two. This error is the phase error signal, which contains information about the phase deviation in the current system.

[0098] A3: Perform a proportional operation on the phase error signal to obtain a phase compensation amount.

[0099] Perform a proportional operation on the phase error signal to obtain a phase compensation amount. The magnitude and direction of the phase error signal directly determine the amount of phase to be compensated.

[0100] Through proportional operation (such as a proportional control algorithm), the amount of phase to be compensated can be calculated based on the error signal. This is a closed-loop control process that ensures the error is gradually reduced and the system reaches an ideal state.

[0101] In a possible implementation, the calculation formula for the proportional operation is Pc = K × Pe, where Pc is the phase compensation amount, K is the proportionality coefficient, and Pe is the phase error signal. Since the error amount is the sum of the noises of the round-trip of the link, the value of K can be, but is not limited to, 0.5.

[0102] A4: Perform the phase output step limit on the phase compensation amount to obtain a compensation signal.

[0103] Perform a step limit on the phase compensation amount to ensure that the phase adjustment during the compensation process will not be too large, thereby avoiding over-regulation or instability of the system.

[0104] The purpose of the phase output step limit is to control the amount of each phase adjustment and avoid jumps with too large amplitudes. Usually, the step limit can be implemented through hardware or software algorithms to control the phase step size of each update, thereby achieving smooth regulation.

[0105] In a possible implementation, the performing the phase output step limit on the phase compensation amount to obtain a compensation signal includes: Calculate the target phase step, and combine the target phase step and the phase output step limit formula to perform the phase output step limit on the phase compensation amount to obtain a compensation signal.

[0106] Among them, the phase output step limit formula is Pci = Pc(i - 1)+△P, where Pci is the compensation signal; Pc(i - 1) is the previous compensation signal; △P is the phase control increment. When i is less than n, △P = ±|Pstep|, and when i is equal to n, △P = ±(|Pc|-|Pstep|×(n - 1)); i is the step output ordinal number, and i is a positive integer; n is the number of step outputs, n = ⌊|Pc| / |Pstep|⌋ + 1; Pc is the phase compensation amount; Pstep is the target phase step, and Pstep = πfout / fsys, where fout is the output frequency of the direct digital synthesis unit, and fsys is the system clock of the direct digital synthesis unit.

[0107] It should be noted that the positive or negative sign of △P depends on the direction of Pc. If the phase to be compensated needs to be advanced, it is positive, otherwise it is negative. n = ⌊|Pc| / |Pstep|⌋ + 1 means taking the floor of |Pc| / |Pstep| and then adding 1.

[0108] In a possible implementation, fout can be, but is not limited to, 50 MHz (megahertz), and fsys can be, but is not limited to, 500 MHz (megahertz). Therefore, Pstep = 0.1π.

[0109] A5: Perform the digital signal synthesis on the compensation signal to obtain the drive signal.

[0110] Step A5: Synthesize the compensation signal into a drive signal in digital domain.

[0111] Generate a drive signal according to the compensation signal through digital signal synthesis technology, and finally feedback the drive signal to the system to achieve phase compensation.

[0112] Digital signal synthesis involves converting the control quantity into a signal form suitable for system input, which can ensure that the drive signal can accurately compensate the phase deviation in the system.

[0113] The key to the process of Steps A1 - A5 is to generate a drive signal through demodulation of the beat frequency optical signal, calculation of the phase error, calculation and control of the phase compensation amount, and finally generate a drive signal through digital signal synthesis, so as to achieve phase compensation. Each step ensures that the drive signal accurately and real - time reflects the phase deviation in the system, and realizes precise adjustment of the phase through closed - loop control.

[0114] S306: Use the drive signal to perform phase compensation on the target optical fiber link to form a real - time closed - loop compensation.

[0115] Use the obtained drive signal to perform phase compensation on the target optical fiber link to complete real - time closed - loop compensation, which can ensure that the phase error in the optical fiber link is compensated in time, thus maintaining the signal quality and system stability.

[0116] Through closed - loop control technology, adjust the drive signal in real - time according to the feedback signal, correct the phase deviation in the link, and ensure the stability and accuracy of optical signal transmission.

[0117] In a possible implementation, the method further includes: Perform partial transmission processing on the modulation signal to obtain a second output signal. Specifically, after performing phase compensation on the target optical fiber link, generate a new second output signal based on the transmitted optical signal for output.

[0118] Specifically, the received modulation signal can also be partially transmitted to obtain a second output signal. At the same time, during the transmission process, the phase of the optical signal will be compensated to restore its accuracy. Finally, based on the phase - compensated signal, a new second output signal (i.e., the compensated and stable second output signal) can be generated and output.

[0119] In addition, an embodiment of the present application also provides a real - time closed - loop phase compensation device for an optical fiber link, including: a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the real - time closed - loop phase compensation method for the optical fiber link as described above is implemented.

[0120] In addition, an embodiment of the present application also provides a computer-readable storage medium. Instructions are stored in the computer-readable storage medium. When the instructions run on a terminal device, the terminal device is caused to execute the real-time closed-loop phase compensation method for an optical fiber link as described above.

[0121] Based on the content of S301 - S307 above, it can be seen that the present application uses digital signal synthesis technology to achieve phase compensation for an optical fiber link, so that only one proportional link is required to complete effective noise suppression. This method does not require complex fine-tuning according to the actual link conditions and has strong environmental adaptability. At the same time, the present application breaks through the limitation of the phase dynamic range within one cycle in the traditional method by restricting the phase output step of the radio frequency signal and accumulating the phase shift amount on the basis of the previous compensation signal, thus realizing a phase shift with a theoretically infinite range of positive and negative values. This not only significantly improves the phase adjustment ability and stability of the system, but also can achieve efficient suppression of link noise over a wide range.

[0122] The real-time closed-loop phase compensation system, method and related devices provided by the present application have been introduced in detail above. The various embodiments in the specification are described in a progressive manner, and the key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method part. It should be noted that for those of ordinary skill in the art in the technical field of the present application, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

[0123] It should be understood that in the present application, "at least one (item)" means one or more, and "a plurality" means two or more. "And / or" is used to describe the association relationship of associated objects and indicates that three relationships can exist. For example, "A and / or B" can represent: only A exists, only B exists, and both A and B exist at the same time. Among them, A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after. "At least one (one) of the following" or a similar expression means any combination of these items, including any combination of single item (one) or plural items (ones). For example, at least one (one) of a, b or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a, b and c", where a, b and c can be single or multiple.

[0124] It should also be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent in such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

Claims

1. A real-time closed-loop phase compensation system for an optical fiber link, characterized in that: The system comprises: a transmitting end and a receiving end; the transmitting end is connected to the receiving end through a target optical fiber link; the transmitting end comprises a beam splitter, a Faraday reflector, a first acousto-optic modulator and a phase extraction and compensation unit; the receiving end comprises a second acousto-optic modulator and a Faraday half-reflecting half-mirror; the beam splitter is connected to the Faraday reflector; the beam splitter is also connected to the first acousto-optic modulator; the first acousto-optic modulator is connected to the second acousto-optic modulator through the target optical fiber link; the second acousto-optic modulator is connected to the Faraday half-reflecting half-mirror; the beam splitter is connected to the phase extraction and compensation unit; the phase extraction and compensation unit is connected to the first acousto-optic modulator; The beam splitter is used to optically split the transmitted optical signal to obtain a first initial signal and a second initial signal; The Faraday reflector is used to optically reflect the first initial signal to obtain a reference signal; The first acousto-optic modulator is used to perform acousto-optic frequency shift on the second initial signal to obtain a first output signal; The target optical fiber link is used to transmit the first output signal to obtain a received signal; The second acousto-optic modulator is used to perform acousto-optic frequency shift on the received signal to obtain a modulated signal; The Faraday half-reflector and half-mirror is used to perform partial reflection processing on the modulated signal to obtain a reflected signal, so that the second acousto-optic modulator, the target optical fiber link and the first acousto-optic modulator perform a first acousto-optic frequency shift, signal transmission and a second acousto-optic frequency shift on the reflected signal in sequence to obtain a feedback signal; The beam splitter is further used to perform a beat frequency on the feedback signal and the reference signal to obtain a beat frequency optical signal; The phase extraction and compensation unit is used to perform phase output step limit and digital signal synthesis on the phase error of the beat frequency optical signal to obtain a driving signal, so as to use the driving signal to perform phase compensation on the target optical fiber link through the first acousto-optic modulator to form a real-time closed-loop compensation; the phase error of the beat frequency optical signal is calculated based on the radio frequency reference signal; the phase output step limit performs phase limitation on the basis of the last compensation signal.

2. The system according to claim 1, characterized in that The phase extraction and compensation unit includes: a photoelectric detector, a phase error extraction module, a proportional operation module, a step output unit and a direct digital synthesis unit; The beam splitter is connected to the photodetector; the phase error extraction module is connected to the photodetector and the proportional operation module respectively; the proportional operation module is connected to the step output unit; the step output unit is connected to the direct digital synthesis unit; The photoelectric detector is used to perform photoelectric demodulation on the beat frequency optical signal to obtain a radio frequency signal; The phase error extraction module is used to calculate the error between the RF signal and the RF reference signal to obtain a phase error signal; The proportional operation module is used to perform proportional operation on the phase error signal to obtain a phase compensation amount; The step output unit is used to perform the phase output step limit on the phase compensation amount to obtain a compensation signal; The direct digital synthesis unit is used to perform the digital signal synthesis on the compensation signal to obtain the driving signal.

3. The system according to claim 2, characterized in that The step output unit is specifically used for: Calculate target phase step; In combination with the target phase step and the phase output step limit formula, the phase output step limit is performed on the phase compensation amount to obtain a compensation signal; Among them, the phase output step limit formula is Pci=Pc(i-1)+△P, Pci is the compensation signal; Pc(i-1) is the previous compensation signal; △P is the phase control increment, when i is less than n, △P=±|Pstep|, when i is equal to n, △P=±(|Pc|-|Pstep|×(n-1)); i is the step output ordinal number, i is a positive integer; n is the step output step number, n=⌊|Pc| / |Pstep|⌋+1; Pc is the phase compensation amount; Pstep is the target phase step, Pstep=πfout / fsys, fout is the output frequency of the direct digital synthesis unit, and fsys is the system clock of the direct digital synthesis unit.

4. The system according to any one of claims 1 to 3, characterized in that: The Faraday half-reflector and half-lens are also used for: Performing partial transmission processing on the modulated signal to obtain a second output signal; After the target optical fiber link performs phase compensation, the system generates a new second output signal based on the transmitted optical signal for output.

5. A real-time closed-loop phase compensation method for an optical fiber link, characterized in that: The method comprises: Optically splitting the transmitted optical signal to obtain a first initial signal and a second initial signal, and optically reflecting the first initial signal to obtain a reference signal; Performing acousto-optic frequency shift on the second initial signal to obtain a first output signal, and transmitting the first output signal through a target optical fiber link to obtain a received signal; Performing acousto-optic frequency shift on the received signal to obtain a modulated signal; Performing partial reflection processing on the modulated signal to obtain a reflected signal; Performing secondary signal transmission on the reflected signal through the target optical fiber link, and performing acousto-optic frequency shift on the reflected signal that has been secondary transmitted through the target optical fiber link to obtain a feedback signal; The feedback signal and the reference signal are beat-frequencyed to obtain a beat-frequency optical signal, and a phase error of the beat-frequency optical signal is subjected to phase output step limit and digital signal synthesis to obtain a driving signal; the phase error of the beat-frequency optical signal is calculated based on a radio frequency reference signal; the phase output step limit is phase limited based on the last compensation signal; The drive signal is used to perform phase compensation on the target optical fiber link to form a real-time closed-loop compensation.

6. The method according to claim 5, characterized in that The step of performing phase output step limitation and digital signal synthesis on the phase error of the beat frequency optical signal to obtain a driving signal comprises: Performing photoelectric demodulation on the beat frequency optical signal to obtain a radio frequency signal; Calculating the error between the radio frequency signal and the radio frequency reference signal to obtain a phase error signal; Performing a proportional operation on the phase error signal to obtain a phase compensation amount; Performing the phase output step limit on the phase compensation amount to obtain a compensation signal; The drive signal is obtained by performing the digital signal synthesis on the compensation signal.

7. The method according to claim 6, characterized in that The step of performing the phase output step limit on the phase compensation amount to obtain a compensation signal includes: Calculate target phase step; In combination with the target phase step and the phase output step limit formula, the phase output step limit is performed on the phase compensation amount to obtain a compensation signal; Among them, the phase output step limit formula is Pci=Pc(i-1)+△P, Pci is the compensation signal; Pc(i-1) is the previous compensation signal; △P is the phase control increment, when i is less than n, △P=±|Pstep|, when i is equal to n, △P=±(|Pc|-|Pstep|×(n-1)); i is the step output ordinal number, i is a positive integer; n is the step output step number, n=⌊|Pc| / |Pstep|⌋+1; Pc is the phase compensation amount; Pstep is the target phase step, Pstep=πfout / fsys, fout is the output frequency of the direct digital synthesis unit, and fsys is the system clock of the direct digital synthesis unit.

8. The method according to any one of claims 5 to 7, characterized in that: The method further comprises: Performing partial transmission processing on the modulated signal to obtain a second output signal; Wherein, after the target optical fiber link performs phase compensation, a new second output signal is generated based on the transmitted optical signal for output.

9. A real-time closed-loop phase compensation device for an optical fiber link, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the real-time closed-loop phase compensation method for an optical fiber link as described in any one of claims 5 to 8 is implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores instructions, and when the instructions are executed on a terminal device, the terminal device executes the real-time closed-loop phase compensation method for an optical fiber link as described in any one of claims 5 to 8.

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