Method for suppressing polarization change during optical frequency signal beat frequency process and related device

Abstract

The present application discloses a method for suppressing polarization change during the beat frequency process of an optical frequency signal and related devices. First, a laser signal emitted by a laser and a transmitted optical signal emitted by an optical fiber link are obtained. Then, the polarization of the laser signal is rotated to obtain a rotated laser signal. Next, the rotated laser signal and the transmitted optical signal are respectively subjected to polarization beam splitting to obtain first and second horizontally polarized optical signals and first and second vertically polarized optical signals. Based on these signals, quadrature beat frequency, photoelectric demodulation, power detection, and phase detection are performed to obtain a first voltage, a second voltage, a first error, and a second error. Finally, the phase of the laser is adjusted by combining these voltages, errors, and a bias amount to ensure that the laser signal emitted by the laser and the transmitted optical signal emitted by the optical fiber link are phase-synchronized during beat frequency. The present application can effectively compensate for the influence of polarization state changes caused by stress, birefringence effects, etc. on beat frequency.

Description

Technical Field

[0001] This application relates to the technical field of signal processing, and particularly to a method for suppressing polarization change during the beat frequency process of an optical frequency signal and related devices. Background Art

[0002] In a field optical fiber link, due to the influence of factors such as temperature and stress, the birefringence effect changes, resulting in a random change in the polarization state of the transmitted optical signal. This instability of the polarization state is particularly important during the relay process, user usage process, or out-of-loop evaluation process, because these processes require beating the transmitted optical signal with a laser signal to obtain a stable radio frequency signal. However, due to the random change in the polarization state of the transmitted optical signal, the power of the radio frequency signal obtained by beating becomes unstable, which not only reduces the signal-to-noise ratio of the radio frequency signal, but also may cause problems such as phase out-of-step and cycle ambiguity. These problems will further lead to phase jump points during the relay, user usage, or out-of-loop evaluation process, destroying the continuity of the optical frequency signal phase, thus seriously affecting the reliability and stability of optical frequency transmission and limiting the transmission distance of optical signals in the optical fiber.

[0003] Therefore, how to effectively compensate for the change in the birefringence effect caused by factors such as temperature and stress in the optical fiber link, thereby stabilizing the polarization state of the optical signal, ensuring the stability of the radio frequency signal after beating, and improving the reliability of optical frequency transmission and the transmission distance of the system, is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0004] Based on the above problems, this application provides a method for suppressing polarization change during the beat frequency process of an optical frequency signal and related devices, which can effectively compensate for the change in the birefringence effect caused by factors such as temperature and stress in the optical fiber link, thereby stabilizing the polarization state of the optical signal, ensuring the stability of the radio frequency signal after beating, and improving the reliability of optical frequency transmission and the transmission distance of the system.

[0005] The embodiments of this application disclose the following technical solutions:

[0006] A method for suppressing polarization change during the beat frequency process of an optical frequency signal, the method comprising:

[0007] Obtain a laser signal and a transmitted optical signal; the transmitted optical signal is an optical signal to be beat with the laser signal; the transmitted optical signal is sent out by an optical fiber link; the laser signal is emitted by a laser;

[0008] Perform polarization rotation on the laser signal to obtain a rotated laser signal;

[0009] The rotation laser signal is subjected to polarization beam splitting to obtain a first horizontally polarized light signal and a first vertically polarized light signal, and the transmitted light signal is subjected to polarization beam splitting to obtain a second horizontally polarized light signal and a second vertically polarized light signal;

[0010] Based on the first horizontally polarized light signal, the second horizontally polarized light signal, the first vertically polarized light signal and the second vertically polarized light signal, quadrature beat frequency, photoelectric demodulation, power detection and phase detection are performed to obtain a first voltage, a second voltage, a first error and a second error; the first voltage is obtained by performing quadrature beat frequency and photoelectric demodulation based on the first horizontally polarized light signal and the second horizontally polarized light signal; the second voltage is obtained by performing quadrature beat frequency and photoelectric demodulation based on the first vertically polarized light signal and the second vertically polarized light signal;

[0011] Combining the first voltage, the second voltage, the first error, the second error and a bias amount, the phase of the laser is adjusted so that the laser signal emitted by the laser is phase-synchronized with the transmitted light signal emitted by the optical fiber link during beat frequency; the bias amount is the deviation value between the first error and the second error.

[0012] In a possible implementation manner, the performing quadrature beat frequency, photoelectric demodulation, power detection and phase detection based on the first horizontally polarized light signal, the second horizontally polarized light signal, the first vertically polarized light signal and the second vertically polarized light signal to obtain a first voltage, a second voltage, a first error and a second error includes:

[0013] The first horizontally polarized light signal and the second horizontally polarized light signal are subjected to quadrature beat frequency to obtain a horizontal beat frequency signal, and the first vertically polarized light signal and the second vertically polarized light signal are subjected to quadrature beat frequency to obtain a vertical beat frequency signal;

[0014] The horizontal beat frequency signal is subjected to photoelectric demodulation to obtain a first horizontal radio frequency signal and a second horizontal radio frequency signal, and the vertical beat frequency signal is subjected to the photoelectric demodulation to obtain a first vertical radio frequency signal and a second vertical radio frequency signal;

[0015] The power detection is respectively performed on the first horizontal radio frequency signal and the first vertical radio frequency signal to obtain a first voltage and a second voltage, and the phase detection is respectively performed on the second horizontal radio frequency signal and the second vertical radio frequency signal in combination with a radio frequency reference signal to obtain a first error and a second error.

[0016] In a possible implementation, combining the first voltage, the second voltage, the first error, the second error, and the bias amount to perform phase adjustment on the laser so that the laser signal emitted by the laser is phase-synchronized with the transmitted optical signal emitted by the optical fiber link during beat frequency, includes:

[0017] Calculating the difference between the first error and the second error to obtain the bias amount;

[0018] Combining the first voltage, the second voltage, the first error, the second error, and the bias amount to determine an output error;

[0019] Performing proportional-integral regulation on the output error to obtain a servo control signal;

[0020] Performing phase adjustment on the laser based on the servo control signal so that the laser signal emitted by the laser is phase-synchronized with the transmitted optical signal emitted by the optical fiber link during beat frequency.

[0021] In a possible implementation, combining the first voltage, the second voltage, the first error, the second error, and the bias amount to determine an output error, includes:

[0022] If the first voltage is less than the second voltage, determining the first error as the output error;

[0023] If the first voltage is greater than the second voltage, determining the sum of the second error and the bias amount as the output error.

[0024] In a possible implementation, combining a radio frequency reference signal to perform the phase detection on the second horizontal radio frequency signal and the second vertical radio frequency signal respectively to obtain a first error and a second error, includes:

[0025] Calculating the phase difference between the second horizontal radio frequency signal and the radio frequency reference signal to obtain the first error;

[0026] Calculating the phase difference between the second vertical radio frequency signal and the radio frequency reference signal to obtain the second error.

[0027] An apparatus for suppressing polarization change during the beat frequency of an optical frequency signal, the apparatus includes:

[0028] An acquisition unit, configured to acquire a laser signal and a transmitted optical signal; the transmitted optical signal is an optical signal to be beat-frequency with the laser signal; the transmitted optical signal is emitted by an optical fiber link; the laser signal is emitted by a laser;

[0029] A polarization rotation unit for performing polarization rotation on the laser signal to obtain a rotated laser signal;

[0030] A polarization beam splitting unit for performing polarization beam splitting on the rotated laser signal to obtain a first horizontally polarized light signal and a first vertically polarized light signal, and performing polarization beam splitting on the transmitted light signal to obtain a second horizontally polarized light signal and a second vertically polarized light signal;

[0031] A synthesis unit for performing quadrature beat frequency, photoelectric demodulation, power detection and phase detection based on the first horizontally polarized light signal, the second horizontally polarized light signal, the first vertically polarized light signal and the second vertically polarized light signal to obtain a first voltage, a second voltage, a first error and a second error; the first voltage is obtained by performing quadrature beat frequency and photoelectric demodulation based on the first horizontally polarized light signal and the second horizontally polarized light signal; the second voltage is obtained by performing quadrature beat frequency and photoelectric demodulation based on the first vertically polarized light signal and the second vertically polarized light signal;

[0032] A first phase adjustment unit for combining the first voltage, the second voltage, the first error, the second error and a bias amount to perform phase adjustment on the laser, so that the laser signal emitted by the laser is phase-synchronized with the transmitted light signal emitted by the optical fiber link during beat frequency; the bias amount is the deviation value between the first error and the second error.

[0033] In a possible implementation manner, the synthesis unit specifically includes:

[0034] A quadrature beat frequency unit for performing quadrature beat frequency on the first horizontally polarized light signal and the second horizontally polarized light signal to obtain a horizontal beat frequency signal, and performing quadrature beat frequency on the first vertically polarized light signal and the second vertically polarized light signal to obtain a vertical beat frequency signal;

[0035] A photoelectric demodulation unit for performing photoelectric demodulation on the horizontal beat frequency signal to obtain a first horizontal radio frequency signal and a second horizontal radio frequency signal, and performing the photoelectric demodulation on the vertical beat frequency signal to obtain a first vertical radio frequency signal and a second vertical radio frequency signal;

[0036] A power detection unit for respectively performing the power detection on the first horizontal radio frequency signal and the first vertical radio frequency signal to obtain a first voltage and a second voltage;

[0037] A phase detection unit for respectively performing the phase detection on the second horizontal radio frequency signal and the second vertical radio frequency signal in combination with a radio frequency reference signal to obtain a first error and a second error.

[0038] In a possible implementation manner, the first phase adjustment unit specifically includes:

[0039] An offset calculation unit, configured to calculate a difference between the first error and the second error to obtain the offset;

[0040] An output error determination unit, configured to determine an output error by combining the first voltage, the second voltage, the first error, the second error, and the offset;

[0041] A proportional-integral regulation unit, configured to perform proportional-integral regulation on the output error to obtain a servo control signal;

[0042] A second phase adjustment unit, configured to perform phase adjustment on the laser based on the servo control signal, so that the laser signal emitted by the laser is phase-synchronized with the transmitted optical signal emitted by the optical fiber link during beat frequency.

[0043] An apparatus for suppressing polarization change during the beat frequency of an optical frequency signal, comprising: a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein when the processor executes the computer program, the method for suppressing polarization change during the beat frequency of an optical frequency signal as described above is implemented.

[0044] A computer-readable storage medium, in which instructions are stored, and when the instructions are run on a terminal device, the terminal device is caused to execute the method for suppressing polarization change during the beat frequency of an optical frequency signal as described above.

[0045] Compared with the prior art, the present application has the following beneficial effects:

[0046] The present application provides a method and related device for suppressing polarization change during the beat frequency process of an optical frequency signal. Specifically, when implementing the method for suppressing polarization change during the beat frequency process of the optical frequency signal provided in the embodiments of the present application, first, a laser signal emitted by a laser and a transmitted optical signal emitted by an optical fiber link are acquired, where the transmitted optical signal will be beat with the laser signal. Then, the polarization of the laser signal is rotated to generate a rotated laser signal. Next, the rotated laser signal is polarization split into a first horizontally polarized optical signal and a first vertically polarized optical signal, and at the same time, the transmitted optical signal is polarization split into a second horizontally polarized optical signal and a second vertically polarized optical signal. Based on these signals, quadrature beat frequency, photoelectric demodulation, power detection, and phase detection are performed to obtain a first voltage, a second voltage, a first error, and a second error, where the first voltage and the second voltage are obtained based on the quadrature beat frequency and photoelectric demodulation results of the horizontally polarized optical signal and the vertically polarized optical signal respectively. Finally, by combining the first voltage, the second voltage, the first error, the second error, and the bias amount (i.e., the deviation value between the first error and the second error), the phase of the laser is adjusted so that the laser signal emitted by the laser and the transmitted optical signal emitted by the optical fiber link are phase synchronized during beat frequency.

[0047] Through technologies such as quadrature beat frequency, photoelectric demodulation, and phase detection, the present application deeply analyzes polarized optical signals and adjusts the bias amount according to the error, thereby compensating for the polarization state change caused by stress, birefringence effect, etc., and reducing the influence brought by polarization instability. At the same time, by acquiring the transmitted optical signal and the laser signal, rotating and splitting the polarization of the laser signal, and finally precisely adjusting the phase of the laser in combination with the bias amount, it can be ensured that the laser signal and the optical signal transmitted by the optical fiber link are always phase synchronized during the beat frequency process. This greatly improves the stability of the optical frequency signal. In addition, due to the ability to continuously and stably maintain the phase synchronization between the laser signal and the transmitted optical signal, it helps to extend the stable transmission distance of the optical signal in the optical fiber. Description of the Drawings

[0048] To more clearly illustrate the technical solutions in the embodiments or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following-described drawings 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.

[0049] Figure 1 It is a flowchart of a method for suppressing polarization change during the beat frequency process of an optical frequency signal provided in the embodiments of the present application;

[0050] Figure 2 It is a flowchart of a signal processing method provided in the embodiments of the present application;

[0051] Figure 3 A method flow chart of a phase adjustment method provided in an embodiment of the present application;

[0052] Figure 4 A schematic diagram of the structure of a device for suppressing polarization changes during the beat process of an optical frequency signal provided in an embodiment of the present application. DETAILED DESCRIPTION

[0053] To facilitate understanding of the technical solutions provided by the embodiments of the present application, the background technology involved in the embodiments of the present application will be described below.

[0054] In the actual optical fiber link, the birefringence effect of the optical fiber link will change because the optical fiber will be affected by factors such as temperature and stress in the actual environment, which will cause random fluctuations in the polarization state of the transmitted optical signal. This change in polarization state will cause the polarization characteristics of the optical signal to be unstable, which in turn affects the processing and transmission of the signal. In the relay process, user use process or out-of-loop evaluation process, it is usually necessary to beat the transmitted optical signal with the laser signal to obtain the radio frequency signal. However, due to the unstable change of the polarization state of the optical signal transmitted by the optical fiber, this will cause the radio frequency signal power obtained in the beating process to fluctuate, thereby affecting the signal-to-noise ratio of the radio frequency signal. Specifically, it manifests as phase desynchronization, cycle ambiguity and other problems. These problems further lead to phase jumps in the process of relaying, user use or out-of-loop evaluation, which may destroy the continuity of the phase of the optical frequency signal. Ultimately, this instability greatly affects the reliability and stability of the optical frequency signal transmission, limits the transmission distance of the optical signal in the optical fiber, and seriously restricts the performance and application of the optical fiber communication system.

[0055] In addition, some current optical fiber communication systems use electrically controlled polarization controllers to deal with random fluctuations in polarization states. By adjusting the amount of birefringence effect in the link, the polarization state of the optical signal is controlled to ensure that the radio frequency signal power and signal-to-noise ratio obtained after the beat frequency with the laser signal are high enough. However, during this adjustment process, the adjustment of the link birefringence effect by the electrically controlled polarization controller may cause a drastic change in polarization mode dispersion, resulting in a femtosecond or even ten-femtosecond jump in the optical frequency signal transmission phase. This phase jump will seriously affect the stability of the optical signal, especially in long-distance transmission links of the order of thousands of kilometers, where the polarization state of the transmitted light fluctuates violently. Frequent adjustment of the polarization controller will further aggravate this instability, resulting in a significant decrease in the transmission stability of the optical signal, thereby affecting the performance and reliability of the entire optical fiber communication system. Therefore, it is not reliable to use an electrically controlled polarization controller to deal with random fluctuations in polarization states. Although this method can effectively adjust the polarization state of the optical signal and improve the signal power and signal-to-noise ratio, the drastic changes in polarization mode dispersion and phase jumps it brings, especially in long-distance transmission, will significantly affect the stability of the system.

[0056] To solve this problem, an embodiment of the present application provides a method and related device for suppressing polarization change during the beat frequency process of an optical frequency signal. First, a laser signal and a transmitted optical signal are obtained. The transmitted optical signal is emitted by an optical fiber link and will be beat with the laser signal. Then, the polarization of the laser signal is rotated to obtain a rotated laser signal. Subsequently, the rotated laser signal and the transmitted optical signal are respectively subjected to polarization beam splitting to obtain optical signals with horizontal and vertical polarizations. Through quadrature beat frequency, optical demodulation, power detection, and phase detection, these signals are processed to obtain a first voltage, a second voltage, a first error, and a second error. Based on these voltages and error signals, combined with the bias amount (i.e., the deviation between the first error and the second error), the phase of the laser is adjusted to ensure that the laser signal and the transmitted optical signal are phase-synchronized during beat frequency. Through technologies such as quadrature beat frequency, optical demodulation, and phase detection, the present application deeply analyzes the polarized optical signal and adjusts the bias amount according to the detected error, thereby effectively compensating for the polarization state change caused by the birefringence effect and reducing the influence brought by polarization instability. At the same time, by obtaining the transmitted optical signal and the laser signal, and performing polarization rotation and beam splitting processing on the laser signal, and finally combining the bias amount to precisely adjust the phase of the laser, the present application ensures that the laser signal and the optical signal transmitted by the optical fiber link are always phase-synchronized during the beat frequency process. This greatly improves the stability of the optical frequency signal, and since the phase synchronization between the laser signal and the transmitted optical signal can be continuously and stably maintained, it helps to extend the stable transmission distance of the optical signal in the optical fiber.

[0057] 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 of 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.

[0058] See Figure 1 , which is a flowchart of a method for suppressing polarization change during the beat frequency process of an optical frequency signal provided by an embodiment of the present application. As Figure 1 shown, the method for suppressing polarization change during the beat frequency process of the optical frequency signal may include steps S101 - S105:

[0059] S101: Obtain a laser signal and a transmitted optical signal.

[0060] At the beginning of the entire phase difference adjustment process, it is first necessary to obtain two optical signals: a laser signal and a transmitted optical signal. The laser signal is generated and emitted by a laser, while the transmitted optical signal is sent out through an optical fiber link. The transmitted optical signal is the optical signal that will be heterodyned with the laser signal during the relay process, user usage process, or out-of-loop evaluation process.

[0061] S102: Perform polarization rotation on the laser signal to obtain a rotated laser signal.

[0062] After obtaining the laser signal and the transmitted optical signal, polarization rotation processing can be performed on the laser signal, that is, changing its polarization direction, so as to obtain a rotated laser signal. The purpose of this process is to change the characteristics of the laser signal so that the rotated laser signal meets the requirements of the system. Through optical beam splitting and polarization rotation, the propagation characteristics of the laser signal can be precisely controlled and adjusted.

[0063] It should be noted that the polarization rotation of the laser signal can be achieved by rotating a Faraday rotator. The angle of polarization rotation can be, but is not limited to, 45 degrees.

[0064] In a possible implementation, if it is necessary to transmit the laser signal to the next stage or the user, a beam splitter can be used to split the laser signal into two identical laser signals. One of the split laser signals is transmitted to the next stage or the user, and the other split laser signal is used for polarization rotation to obtain a rotated laser signal.

[0065] It should be noted that a beam splitter is an optical element whose main function is to split an incident light beam into two or more light beams with a certain ratio.

[0066] S103: Perform polarization beam splitting on the rotated laser signal to obtain a first horizontally polarized optical signal and a first vertically polarized optical signal, and perform polarization beam splitting on the transmitted optical signal to obtain a second horizontally polarized optical signal and a second vertically polarized optical signal.

[0067] The purpose of performing polarization beam splitting on the rotated laser signal is to divide it into two optical signals with different polarization directions, respectively obtaining a first horizontally polarized optical signal and a first vertically polarized optical signal. At the same time, a similar polarization beam splitting operation is performed on the transmitted optical signal to also divide it into two optical signals with different polarization directions, obtaining a second horizontally polarized optical signal and a second vertically polarized optical signal. Through this polarization beam splitting method, each optical signal can be separated according to its polarization direction for subsequent signal processing and analysis.

[0068] It should be noted that the polarization splitting of the rotating laser signal and the transmitted optical signal can be achieved by a Polarizing Beam Splitter (PBS).

[0069] S104: Based on the first horizontal polarization optical signal, the second horizontal polarization optical signal, the first vertical polarization optical signal, and the second vertical polarization optical signal, perform quadrature beat frequency, optical demodulation, power detection, and phase detection to obtain a first voltage, a second voltage, a first error, and a second error.

[0070] Based on four polarization optical signals - the first horizontal polarization optical signal, the second horizontal polarization optical signal, the first vertical polarization optical signal, and the second vertical polarization optical signal, perform a series of processing steps, including quadrature beat frequency, optical demodulation, power detection, and phase detection, so as to obtain a first voltage, a second voltage, a first error, and a second error. Specifically, the first voltage is obtained by performing quadrature beat frequency and optical demodulation on the first horizontal polarization optical signal and the second horizontal polarization optical signal. The second voltage is obtained by performing the same processing steps on the first vertical polarization optical signal and the second vertical polarization optical signal. These steps are aimed at extracting key voltage and error information through precise signal processing techniques for subsequent phase adjustment.

[0071] See Figure 2 , Figure 2 is a flowchart of a signal processing method provided by an embodiment of the present application. Correspondingly, step S104 performs quadrature beat frequency, optical demodulation, power detection, and phase detection based on the first horizontal polarization optical signal, the second horizontal polarization optical signal, the first vertical polarization optical signal, and the second vertical polarization optical signal to obtain a first voltage, a second voltage, a first error, and a second error, and can be specifically implemented through steps A1 - A3:

[0072] A1: Perform quadrature beat frequency on the first horizontal polarization optical signal and the second horizontal polarization optical signal to obtain a horizontal beat frequency signal, and perform quadrature beat frequency on the first vertical polarization optical signal and the second vertical polarization optical signal to obtain a vertical beat frequency signal.

[0073] To obtain the first voltage, the second voltage, the first error, and the second error, two different polarization optical signals can be first subjected to quadrature beat frequency processing. Specifically, first perform quadrature beat frequency on the first horizontal polarization optical signal and the second horizontal polarization optical signal (i.e., amplify the frequency difference between these two signals through specific mathematical or physical means), so as to obtain a new signal - the horizontal beat frequency signal.

[0074] Similarly, in the second step, the first vertical polarization optical signal and the second vertical polarization optical signal are processed in the same way to obtain a vertical beat signal. In this way, by means of orthogonal beat, signals with different polarization directions can be processed separately for subsequent signal analysis and processing.

[0075] A2: The optical demodulation is performed on the horizontal beat signal to obtain a first horizontal radio frequency signal and a second horizontal radio frequency signal, and the optical demodulation is performed on the vertical beat signal to obtain a first vertical radio frequency signal and a second vertical radio frequency signal.

[0076] The purpose of performing optical demodulation on the beat signal is to convert the optical signal into an electrical signal. Specifically, for the previously obtained horizontal beat signal, through the optical demodulation process, two different electrical signals are extracted, which are respectively called the first horizontal radio frequency signal and the second horizontal radio frequency signal.

[0077] Similarly, when the optical demodulation is performed on the vertical beat signal, two electrical signals will also be obtained, which are respectively the first vertical radio frequency signal and the second vertical radio frequency signal. These radio frequency signals are the results of optical demodulation and contain the frequency information of the original optical signal.

[0078] It should be noted that the optical demodulation of the horizontal beat signal and the vertical beat signal can be achieved through a photodetector.

[0079] A3: The power detection is respectively performed on the first horizontal radio frequency signal and the first vertical radio frequency signal to obtain a first voltage and a second voltage, and the phase detection is respectively performed on the second horizontal radio frequency signal and the second vertical radio frequency signal in combination with a radio frequency reference signal to obtain a first error and a second error.

[0080] Finally, the power detection is respectively performed on the first horizontal radio frequency signal and the first vertical radio frequency signal to obtain a first voltage and a second voltage. In combination with the radio frequency reference signal, the phase detection is respectively performed on the second horizontal radio frequency signal and the second vertical radio frequency signal to obtain a first error and a second error. Specifically, the power detection is used to measure the intensity of the radio frequency signal and convert it into a corresponding voltage value; while the phase detection calculates the corresponding error value by comparing the phase difference between the radio frequency signal and the reference signal. These steps are aimed at extracting and quantifying the key parameters of the radio frequency signal and providing basic data for subsequent signal processing and analysis.

[0081] It should be noted that the radio frequency reference signal is a standard radio frequency signal used to provide a reference phase or frequency for comparison and calibration with other radio frequency signals. In the above process, the role of the radio frequency reference signal is:

[0082] Phase Detection Reference: By comparing the second horizontal radio frequency signal and the second vertical radio frequency signal with the radio frequency reference signal, the phase offsets of these signals relative to the reference signal can be accurately measured, thereby obtaining the first error and the second error.

[0083] Ensuring Precision: Using the radio frequency reference signal ensures the precision and consistency of phase detection, making the signal processing results more reliable.

[0084] Specifically, during phase detection, the radio frequency reference signal serves as a known standard phase to determine the phase difference between the signal to be measured and this standard signal. In this way, the phase deviation between signals can be accurately quantified and corrected, thereby achieving precise phase synchronization and adjustment.

[0085] It should also be noted that the power detection of the first horizontal radio frequency signal and the first vertical radio frequency signal can be achieved through a power detector.

[0086] In a possible implementation, in step A1, the phase detection of the second horizontal radio frequency signal and the second vertical radio frequency signal is respectively performed in combination with the radio frequency reference signal to obtain the first error and the second error, which specifically includes the following two steps:

[0087] (1) Calculate the phase difference between the second horizontal radio frequency signal and the radio frequency reference signal:

[0088] Compare the second horizontal radio frequency signal with the radio frequency reference signal and calculate the phase difference between the two to obtain the first error. The first error represents the phase deviation of the second horizontal radio frequency signal relative to the radio frequency reference signal.

[0089] (2) Calculate the phase difference between the second vertical radio frequency signal and the radio frequency reference signal:

[0090] Compare the second vertical radio frequency signal with the radio frequency reference signal and calculate the phase difference between the two to obtain the second error. The second error represents the phase deviation of the second vertical radio frequency signal relative to the radio frequency reference signal.

[0091] Through these two steps, the phase deviations of the second horizontal radio frequency signal and the second vertical radio frequency signal relative to the radio frequency reference signal, namely the first error and the second error, can be clearly determined. These error values will play a key role in subsequent calculations and adjustments, helping to ensure that the laser signal emitted by the laser is phase-synchronized with the transmitted optical signal in the optical fiber link during beat frequency.

[0092] S105: Combine the first voltage, the second voltage, the first error, the second error, and the bias amount to perform phase adjustment on the laser so that the laser signal emitted by the laser is phase-synchronized with the transmitted optical signal emitted by the optical fiber link during beat frequency.

[0093] The operating state of the laser is adjusted by comprehensively considering multiple factors, that is, the phase of the laser is adjusted by using the previously obtained first voltage, second voltage, first error, second error, and bias amount. Specifically, the first voltage and the second voltage represent the power information of the signal, the first error and the second error reflect the phase difference of the signal, and the bias amount is a value calculated from the difference between the first error and the second error. Through these data, the laser can be accurately adjusted to ensure that the laser signal emitted by the laser is phase-consistent with the optical signal transmitted in the optical fiber link at the beat frequency (i.e., the frequency of phase synchronization), thereby ensuring the stability and accuracy of signal transmission.

[0094] See Figure 3 , Figure 3 which is a flowchart of a phase adjustment method provided by an embodiment of the present application. Correspondingly, in step S105, the phase of the laser is adjusted by combining the first voltage, the second voltage, the first error, the second error, and the bias amount, so that the laser signal emitted by the laser is phase-synchronized with the transmitted optical signal emitted by the optical fiber link at the beat frequency, and specifically can be implemented through steps B1 - B4:

[0095] B1: Calculate the difference between the first error and the second error to obtain the bias amount.

[0096] During the phase adjustment process, it is first necessary to determine the difference between two different error values (i.e., the first error and the second error). This difference, called the bias amount, represents the deviation of the system under two error conditions. By calculating this difference, a correction amount can be obtained to help further adjust the phase of the laser to make the synchronization with the optical fiber link transmission signal more accurate. In short, the bias amount reflects the gap between the errors, is used to quantify the relative deviation between the two errors, and provides a necessary reference basis for subsequent adjustment.

[0097] B2: Determine the output error by combining the first voltage, the second voltage, the first error, the second error, and the bias amount.

[0098] "Determine the output error by combining the first voltage, the second voltage, the first error, the second error, and the bias amount" means: Calculate a final output error by comprehensively considering multiple factors (including the first voltage, the second voltage, the first error, the second error, and the bias amount).

[0099] Specifically, if the first voltage is less than the second voltage, the output error directly takes the first error value; conversely, if the first voltage is greater than the second voltage, the second error is added to the bias amount to obtain the output error. The purpose of this process is to select an appropriate error value for correction according to the magnitude relationship of the voltages and in combination with different error situations, so as to ensure the accuracy and stability of the phase adjustment.

[0100] B3: Perform proportional-integral regulation on the output error to obtain a servo control signal.

[0101] The process of "performing proportional-integral regulation on the output error to obtain a servo control signal" refers to generating a control signal based on the output error through a proportional-integral (PI) regulation algorithm to adjust the behavior of the system.

[0102] Specifically, first, the output error refers to the gap between the current state of the system and the desired target, usually a real-time feedback signal used to reflect the deviation of the system. To make the system reach the target state, we need to make appropriate adjustments according to this error. Proportional-integral regulation (PI) is a control method that combines two different control methods:

[0103] Proportional regulation (P): Proportional control adjusts according to the magnitude of the current error. The larger the error, the greater the adjustment of the control signal. In this way, proportional regulation can quickly respond to the error and reduce the deviation of the system.

[0104] Integral regulation (I): Integral control adjusts according to the accumulated amount of the error over a period of time, that is, considering the persistence and historical impact of the error. Through the integral action, the system can correct small errors that have existed for a long time, ensuring that even long-term deviations can be corrected, thus preventing the system from deviating from the target for a long time.

[0105] Combining these two control methods, a comprehensive servo control signal can be obtained through proportional-integral regulation. This control signal is used to drive the actuator of the system and adjust the state of the laser so that the laser signal emitted by it is phase-synchronized with the transmitted optical signal emitted by the optical fiber link during beat frequency.

[0106] B4: Perform phase adjustment on the laser based on the servo control signal so that the laser signal emitted by the laser is phase-synchronized with the transmitted optical signal emitted by the optical fiber link during beat frequency.

[0107] By applying the servo control signal, the phase of the laser signal emitted by the laser can be adjusted to ensure that the laser signal is phase-synchronized with the optical signal transmitted by the optical fiber link during beat frequency.

[0108] Specifically, the servo control signal is a control signal generated by the system based on error feedback, indicating what adjustments the laser needs to make to correct the current state. Phase adjustment refers to changing the phase of the output signal of the laser (i.e., the time delay or angle of the signal), so that the phase relationship between the laser signal and the optical signal transmitted through the optical fiber link reaches the desired state.

[0109] In optical fiber communication or laser systems, beat frequency refers to the periodic change in the phase difference when two signals with different frequencies interact, forming a low-frequency signal. If the phases of the laser signal and the transmitted signal are not synchronized, their beat frequency will be disturbed, which may affect the signal stability and transmission quality. Therefore, to ensure the signal transmission quality, the servo control signal can be used to adjust the output phase of the laser, so that the laser signal is phase-synchronized with the signal transmitted through the optical fiber link, thereby keeping the beat frequency stable and ensuring the accurate transmission of the signal.

[0110] Based on the content of S101 - S105, first, the laser signal is obtained from the laser, and the transmitted optical signal for beat frequency with it is obtained through the optical fiber link. Then, the laser signal is optically split and the rotated laser signal is obtained through polarization rotation. Next, the polarized splitting of the rotated laser signal and the polarized splitting of the transmitted optical signal are performed to obtain four optical signals with different polarization states. Through quadrature beat frequency, optical demodulation, power detection, and phase detection, the first voltage, the second voltage, the first error, and the second error are obtained. Finally, combining these voltage and error signals, the bias amount is calculated and the phase of the laser is adjusted to ensure that the laser signal and the transmitted optical signal are always phase-synchronized during the beat frequency process. This application deeply analyzes the polarized optical signal through technologies such as quadrature beat frequency, optical demodulation, and phase detection, and adjusts the bias amount according to the error to compensate for the polarization state change caused by the birefringence effect and reduce the influence of polarization instability. By obtaining the laser signal and the transmitted optical signal, performing polarization rotation and splitting, and precisely adjusting the phase of the laser in combination with the bias amount, it is ensured that the phase of the optical signal is synchronized with the laser signal during the beat frequency process, thereby greatly improving the stability of the optical frequency signal and extending the stable transmission distance of the optical signal in the optical fiber.

[0111] See Figure 4 , Figure 4 is a schematic structural diagram of a device for suppressing polarization change during the beat frequency process of an optical frequency signal provided by an embodiment of this application. As Figure 4 shown, the device for suppressing polarization change during the beat frequency process of the optical frequency signal includes:

[0112] An acquisition unit 401, configured to acquire a laser signal and a transmitted optical signal; the transmitted optical signal is the optical signal to be beat-frequency with the laser signal; the transmitted optical signal is sent out by the optical fiber link; the laser signal is emitted by the laser;

[0113] The polarization rotation unit 402 is configured to perform polarization rotation on the laser signal to obtain a rotated laser signal;

[0114] The polarization beam splitting unit 403 is configured to perform polarization beam splitting on the rotated laser signal to obtain a first horizontally polarized light signal and a first vertically polarized light signal, and perform polarization beam splitting on the transmitted light signal to obtain a second horizontally polarized light signal and a second vertically polarized light signal;

[0115] The synthesis unit 404 is configured to perform quadrature beat frequency, photoelectric demodulation, power detection, and phase detection based on the first horizontally polarized light signal, the second horizontally polarized light signal, the first vertically polarized light signal, and the second vertically polarized light signal to obtain a first voltage, a second voltage, a first error, and a second error; the first voltage is obtained by performing quadrature beat frequency and photoelectric demodulation on the first horizontally polarized light signal and the second horizontally polarized light signal; the second voltage is obtained by performing quadrature beat frequency and photoelectric demodulation on the first vertically polarized light signal and the second vertically polarized light signal;

[0116] The first phase adjustment unit 405 is configured to combine the first voltage, the second voltage, the first error, the second error, and the bias amount to perform phase adjustment on the laser, so that the laser signal emitted by the laser is phase-synchronized with the transmitted light signal emitted by the optical fiber link during beat frequency; the bias amount is the deviation value between the first error and the second error.

[0117] In a possible implementation manner, the synthesis unit 404 specifically includes:

[0118] The quadrature beat frequency unit is configured to perform quadrature beat frequency on the first horizontally polarized light signal and the second horizontally polarized light signal to obtain a horizontal beat frequency signal, and perform quadrature beat frequency on the first vertically polarized light signal and the second vertically polarized light signal to obtain a vertical beat frequency signal;

[0119] The photoelectric demodulation unit is configured to perform photoelectric demodulation on the horizontal beat frequency signal to obtain a first horizontal radio frequency signal and a second horizontal radio frequency signal, and perform the photoelectric demodulation on the vertical beat frequency signal to obtain a first vertical radio frequency signal and a second vertical radio frequency signal;

[0120] The power detection unit is configured to perform the power detection on the first horizontal radio frequency signal and the first vertical radio frequency signal respectively to obtain a first voltage and a second voltage;

[0121] The phase detection unit is configured to perform the phase detection on the second horizontal radio frequency signal and the second vertical radio frequency signal respectively in combination with a radio frequency reference signal to obtain a first error and a second error.

[0122] In a possible implementation, the first phase adjustment unit 405 specifically includes:

[0123] A bias calculation unit for calculating the difference between the first error and the second error to obtain the bias;

[0124] An output error determination unit for determining an output error by combining the first voltage, the second voltage, the first error, the second error, and the bias;

[0125] A proportional-integral regulation unit for performing proportional-integral regulation on the output error to obtain a servo control signal;

[0126] A second phase adjustment unit for performing phase adjustment on the laser based on the servo control signal so that the laser signal emitted by the laser is phase-synchronized with the transmitted optical signal emitted by the optical fiber link during beat frequency.

[0127] In a possible implementation, the output error determination unit is specifically configured to:

[0128] If the first voltage is less than the second voltage, determine the first error as the output error;

[0129] If the first voltage is greater than the second voltage, determine the sum of the second error and the bias as the output error.

[0130] In a possible implementation, the phase detection unit specifically includes:

[0131] A first error calculation unit for calculating the phase difference between the second horizontal radio frequency signal and the radio frequency reference signal to obtain a first error;

[0132] A second error calculation unit for calculating the phase difference between the second vertical radio frequency signal and the radio frequency reference signal to obtain a second error.

[0133] In addition, an embodiment of the present application further provides a device for suppressing polarization change during the beat frequency of an optical frequency signal, 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 method for suppressing polarization change during the beat frequency of an optical frequency signal as described above is implemented.

[0134] In addition, an embodiment of the present application further provides a computer-readable storage medium. Instructions are stored in the computer-readable storage medium. When the instructions are run on a terminal device, the terminal device is caused to execute the method for suppressing polarization change during the beat frequency of an optical frequency signal as described above.

[0135] An embodiment of the present application provides a device for suppressing polarization change during the beat frequency process of an optical frequency signal. First, an acquisition unit 401 is used to acquire a laser signal and a transmitted optical signal, and a polarization rotation unit 402 is used to perform polarization rotation on the laser signal to obtain a rotated laser signal. A polarization beam splitting unit 403 performs polarization beam splitting on the rotated laser signal to obtain a first horizontally polarized optical signal and a first vertically polarized optical signal, and performs polarization beam splitting on the transmitted optical signal to obtain a second horizontally polarized optical signal and a second vertically polarized optical signal. Then, a synthesis unit 404 performs quadrature beat frequency, photoelectric demodulation, power detection, and phase detection based on the first horizontally polarized optical signal, the second horizontally polarized optical signal, the first vertically polarized optical signal, and the second vertically polarized optical signal to obtain a first voltage, a second voltage, a first error, and a second error, so that a first phase adjustment unit 405 can combine the first voltage, the second voltage, the first error, the second error, and a bias amount to perform phase adjustment on the laser, so that the laser signal emitted by the laser is phase-synchronized with the transmitted optical signal emitted by the optical fiber link during beat frequency. The present application uses quadrature beat frequency, photoelectric demodulation, and phase detection technologies to deeply analyze polarized optical signals, and compensates for the polarization state change caused by the birefringence effect through bias amount adjustment, reducing the influence of polarization instability. At the same time, by acquiring the transmitted optical signal and the laser signal, performing polarization rotation and beam splitting processing on the laser signal, and performing precise phase adjustment on the laser in combination with the bias amount, it is ensured that the laser signal is phase-synchronized with the optical signal transmitted by the optical fiber link during the beat frequency process, greatly improving the stability of the optical frequency signal. This continuously stable phase synchronization characteristic helps to extend the stable transmission distance of the optical signal in the optical fiber.

[0136] The above has introduced in detail a method and related device for suppressing polarization change during the beat frequency process of an optical frequency signal provided by the present application. The various embodiments in the specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, 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.

[0137] It should be understood that in this 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, indicating 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 simultaneously. 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 (item) of the following" or its similar expressions refer to any combination of these items, including any combination of single items (items) or plural items (items). For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0138] 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 such actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variants 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 further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element.

Claims

1. A method for suppressing polarization change during the beat process of an optical frequency signal, characterized in that: The method comprises: Acquire a laser signal and a transmission optical signal; the transmission optical signal is an optical signal that beats with the laser signal; the transmission optical signal is emitted by an optical fiber link; the laser signal is emitted by a laser; Performing polarization rotation on the laser signal to obtain a rotated laser signal; Perform polarization splitting on the rotating laser signal to obtain a first horizontally polarized light signal and a first vertically polarized light signal, and perform polarization splitting on the transmission light signal to obtain a second horizontally polarized light signal and a second vertically polarized light signal; Based on the first horizontally polarized light signal, the second horizontally polarized light signal, the first vertically polarized light signal, and the second vertically polarized light signal, orthogonal beat frequency, photoelectric demodulation, power detection, and phase detection are performed to obtain a first voltage, a second voltage, a first error, and a second error; the first voltage is obtained based on the first horizontally polarized light signal and the second horizontally polarized light signal undergoing orthogonal beat frequency and photoelectric demodulation; the second voltage is obtained based on the first vertically polarized light signal and the second vertically polarized light signal undergoing orthogonal beat frequency and photoelectric demodulation; In combination with the first voltage, the second voltage, the first error, the second error and the offset, the phase of the laser is adjusted so that the laser signal emitted by the laser and the transmission light signal emitted by the optical fiber link maintain phase synchronization at the beat frequency; the offset is the deviation value between the first error and the second error; The method of performing orthogonal beat frequency, photoelectric demodulation, power detection and phase detection based on the first horizontally polarized light signal, the second horizontally polarized light signal, the first vertically polarized light signal and the second vertically polarized light signal to obtain a first voltage, a second voltage, a first error and a second error includes: Performing orthogonal beat frequency on the first horizontal polarized light signal and the second horizontal polarized light signal to obtain a horizontal beat frequency signal, and performing orthogonal beat frequency on the first vertical polarized light signal and the second vertical polarized light signal to obtain a vertical beat frequency signal; Performing photoelectric demodulation on the horizontal beat frequency signal to obtain a first horizontal radio frequency signal and a second horizontal radio frequency signal, and performing photoelectric demodulation on the vertical beat frequency signal to obtain a first vertical radio frequency signal and a second vertical radio frequency signal; The power detection is performed on the first horizontal RF signal and the first vertical RF signal respectively to obtain a first voltage and a second voltage, and the phase detection is performed on the second horizontal RF signal and the second vertical RF signal respectively in combination with a RF reference signal to obtain a first error and a second error.

2. The method according to claim 1, characterized in that The combining the first voltage, the second voltage, the first error, the second error and the offset to adjust the phase of the laser so that the laser signal emitted by the laser and the transmission optical signal emitted by the optical fiber link maintain phase synchronization at the beat frequency, comprises: Calculating the difference between the first error and the second error to obtain the offset; determining an output error by combining the first voltage, the second voltage, the first error, the second error, and the offset; Performing proportional-integral adjustment on the output error to obtain a servo control signal; The phase of the laser is adjusted based on the servo control signal so that the laser signal emitted by the laser and the transmission light signal emitted by the optical fiber link maintain phase synchronization at the beat frequency.

3. The method according to claim 2, characterized in that The determining the output error by combining the first voltage, the second voltage, the first error, the second error and the offset comprises: If the first voltage is less than the second voltage, determining the first error as the output error; If the first voltage is greater than the second voltage, the sum of the second error and the offset is determined as the output error.

4. The method according to claim 1, characterized in that: The performing the phase detection on the second horizontal radio frequency signal and the second vertical radio frequency signal in combination with the radio frequency reference signal to obtain the first error and the second error comprises: Calculating a phase difference between the second horizontal radio frequency signal and the radio frequency reference signal to obtain a first error; A phase difference between the second vertical RF signal and the RF reference signal is calculated to obtain a second error.

5. A device for suppressing polarization changes during the beat frequency process of an optical frequency signal, characterized in that: The device comprises: An acquisition unit, used for acquiring a laser signal and a transmission optical signal; the transmission optical signal is an optical signal that beats with the laser signal; the transmission optical signal is emitted by an optical fiber link; the laser signal is emitted by a laser; a polarization rotation unit, used for performing polarization rotation on the laser signal to obtain a rotated laser signal; a polarization beam splitting unit, configured to perform polarization beam splitting on the rotating laser signal to obtain a first horizontally polarized light signal and a first vertically polarized light signal, and to perform polarization beam splitting on the transmission light signal to obtain a second horizontally polarized light signal and a second vertically polarized light signal; a comprehensive unit, configured to perform orthogonal beat frequency, photoelectric demodulation, power detection, and phase detection on the first horizontally polarized light signal, the second horizontally polarized light signal, the first vertically polarized light signal, and the second vertically polarized light signal to obtain a first voltage, a second voltage, a first error, and a second error; the first voltage is obtained by performing orthogonal beat frequency and photoelectric demodulation on the first horizontally polarized light signal and the second horizontally polarized light signal; the second voltage is obtained by performing orthogonal beat frequency and photoelectric demodulation on the first vertically polarized light signal and the second vertically polarized light signal; a first phase adjustment unit, configured to perform phase adjustment on the laser in combination with the first voltage, the second voltage, the first error, the second error and an offset, so that the laser signal emitted by the laser and the transmission optical signal emitted by the optical fiber link maintain phase synchronization at a beat frequency; the offset is a deviation value between the first error and the second error; The comprehensive unit specifically includes: an orthogonal beat unit, configured to perform an orthogonal beat on the first horizontally polarized light signal and the second horizontally polarized light signal to obtain a horizontal beat signal, and perform an orthogonal beat on the first vertically polarized light signal and the second vertically polarized light signal to obtain a vertical beat signal; an optoelectronic demodulation unit, configured to perform optoelectronic demodulation on the horizontal beat frequency signal to obtain a first horizontal radio frequency signal and a second horizontal radio frequency signal, and perform optoelectronic demodulation on the vertical beat frequency signal to obtain a first vertical radio frequency signal and a second vertical radio frequency signal; a power detection unit, configured to perform the power detection on the first horizontal radio frequency signal and the first vertical radio frequency signal to obtain a first voltage and a second voltage; The phase detection unit is used to perform the phase detection on the second horizontal radio frequency signal and the second vertical radio frequency signal in combination with the radio frequency reference signal to obtain a first error and a second error.

6. The device according to claim 5, characterized in that The first phase adjustment unit specifically includes: an offset calculation unit, configured to calculate a difference between the first error and the second error to obtain the offset; an output error determination unit, configured to determine an output error by combining the first voltage, the second voltage, the first error, the second error, and the offset; A proportional-integral adjustment unit, used for performing proportional-integral adjustment on the output error to obtain a servo control signal; The second phase adjustment unit is used to adjust the phase of the laser based on the servo control signal so that the laser signal emitted by the laser and the transmission light signal emitted by the optical fiber link maintain phase synchronization at the beat frequency.

7. A device for suppressing polarization changes during the beat frequency process of an optical frequency signal, 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 method for suppressing polarization changes in the beat process of an optical frequency signal as described in any one of claims 1 to 4 is implemented.

8. 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 method for suppressing polarization changes in an optical frequency signal beat process as described in any one of claims 1 to 4.

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