Polarization change suppression method in optical frequency signal beat frequency process and related device

Abstract

The invention discloses a polarization change suppression method in an optical frequency signal beat frequency process and a related device. First, a laser signal emitted by a laser and a transmission optical signal emitted by an optical fiber link are obtained. Polarization rotation is carried out on the laser signal to obtain a rotation laser signal; then, polarization beam splitting is carried out on the rotating laser signal and the transmission light signal respectively, and first and second horizontal polarization light signals and first and second vertical polarization light signals are obtained; orthogonal beat frequency, photoelectric demodulation, power detection and phase detection are performed based on the signals to obtain a first voltage, a second voltage, a first error and a second error. And finally, performing phase adjustment on the laser by combining the voltage, the error and the offset so as to ensure that a laser signal emitted by the laser and a transmission optical signal emitted by the optical fiber link are kept in phase synchronization during frequency beating. According to the invention, the influence of polarization state change caused by stress, birefringence effect and the like on beat frequency can be effectively compensated.

Description

Technical Field

[0001] The present application relates to the field of signal processing technology, and in particular to a method and a related device for suppressing polarization changes in an optical frequency signal beat process. Background Art

[0002] In actual optical fiber links, due to factors such as temperature and stress, the birefringence effect will change, resulting in random changes in the polarization state of the transmitted optical signal. This polarization state instability is particularly important during the relay process, user use process, or out-of-loop evaluation process, because these processes require the transmitted optical signal to beat the laser signal to obtain a stable RF signal. However, due to the random changes in the polarization state of the transmitted optical signal, the RF signal power obtained by the beat becomes unstable, which not only reduces the signal-to-noise ratio of the RF signal, but may also cause problems such as phase desynchronization and cycle ambiguity. These problems will further lead to phase jumps during relaying, user use, or out-of-loop evaluation, destroying the continuity of the optical signal phase, thereby seriously affecting the reliability and stability of optical transmission and limiting the transmission distance of the optical signal in the optical fiber.

[0003] Therefore, how to effectively compensate for the changes 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 RF signal after the beat frequency, and improving the reliability of optical frequency transmission and the transmission distance of the system is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0004] Based on the above problems, the present application provides a method and related device for suppressing polarization changes during the beat process of an optical frequency signal, which can effectively compensate for the changes 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 the beat, and improving the reliability of optical frequency transmission and the transmission distance of the system.

[0005] The embodiments of the present application disclose the following technical solutions: A method for suppressing polarization change during an optical frequency signal beat process, the method comprising: 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.

[0006] In a possible implementation, 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.

[0007] In a possible implementation, combining the first voltage, the second voltage, the first error, the second error, and the offset to perform phase adjustment on 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, includes: 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.

[0008] In a possible implementation manner, determining the output error by combining the first voltage, the second voltage, the first error, the second error, and the offset includes: 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.

[0009] In a possible implementation, 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 includes: 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.

[0010] A device for suppressing polarization changes in an optical frequency signal beat process, the device comprising: 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 is used 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 transmitted light signal emitted by the optical fiber link maintain phase synchronization at the beat frequency; the offset is a deviation value between the first error and the second error.

[0011] In a possible implementation, the integration 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.

[0012] In a possible implementation manner, 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.

[0013] A device for suppressing polarization changes during the beat process of an optical frequency signal comprises: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the method for suppressing polarization changes during the beat process of an optical frequency signal as described above is implemented.

[0014] A computer-readable storage medium stores instructions. When the instructions are executed on a terminal device, the terminal device executes the method for suppressing polarization changes in the beat process of an optical frequency signal as described above.

[0015] Compared with the prior art, this application has the following beneficial effects: The present application provides a method for suppressing polarization changes during the beat process of an optical frequency signal and a related device. Specifically, when executing the method for suppressing polarization changes during the beat process of an optical frequency signal provided in an embodiment of the present application, first obtain a laser signal emitted by a laser and a transmission light signal emitted by an optical fiber link, wherein the transmission light signal will beat with the laser signal. Next, the laser signal is polarized and rotated to generate a rotated laser signal. Then, the rotated laser signal is polarized and split to obtain a first horizontally polarized light signal and a first vertically polarized light signal, and at the same time, the transmission light signal is polarized and split to obtain a second horizontally polarized light signal and a second vertically polarized light signal. Based on these signals, 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, wherein the first voltage and the second voltage are respectively obtained based on the orthogonal beat frequency and photoelectric demodulation results of the horizontally polarized light signal and the vertically polarized light signal. Finally, the phase of the laser is adjusted by combining the first voltage, the second voltage, the first error, the second error and the offset (i.e., the deviation value between the first error and the second error) so that the laser signal emitted by the laser and the transmitted light signal emitted by the optical fiber link maintain phase synchronization at the beat frequency.

[0016] This application uses orthogonal beat frequency, photoelectric demodulation and phase detection technologies to conduct an in-depth analysis of polarized light signals, and adjusts the bias amount according to the error, thereby compensating for changes in polarization states caused by stress, birefringence effects, etc., and reducing the impact of polarization instability. At the same time, by obtaining the transmitted light signal and the laser signal, and performing polarization rotation and beam splitting on the laser signal, and finally combining the bias amount to accurately adjust the phase of the laser, it can be ensured that the laser signal and the light signal transmitted by the optical fiber link always maintain phase synchronization during the beat frequency process. This greatly improves the stability of the optical frequency signal. In addition, since the phase synchronization of the laser signal and the transmitted light signal can be maintained continuously and stably, it helps to extend the stable transmission distance of the optical signal in the optical fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in this embodiment or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 A method flow chart of a method for suppressing polarization changes in an optical frequency signal beat process provided in an embodiment of the present application; Figure 2 A method flow chart of a signal processing method provided in an embodiment of the present application; Figure 3 A method flow chart of a phase adjustment method provided in an embodiment of the present application; 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

[0019] 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.

[0020] 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.

[0021] 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.

[0022] In order to solve this problem, a method and a related device for suppressing polarization changes during the beat process of an optical frequency signal are provided in an embodiment of the present application. First, a laser signal and a transmission optical signal are obtained. The transmission optical signal is emitted by an optical fiber link and will beat with the laser signal. Next, the laser signal is polarized and rotated to obtain a rotated laser signal. Then, the rotating laser signal and the transmission optical signal are polarized and split respectively to obtain horizontally and vertically polarized optical signals. These signals are processed by orthogonal beat, photoelectric demodulation, power detection and phase detection to obtain a first voltage, a second voltage, a first error and a second error. According to these voltages and error signals, combined with the offset (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 transmission optical signal maintain phase synchronization during the beat. The present application uses orthogonal beat, photoelectric demodulation and phase detection technologies to conduct an in-depth analysis of the polarized optical signal, and adjusts the offset according to the detected error, thereby effectively compensating for the change in polarization state caused by the birefringence effect and reducing the impact of polarization instability. At the same time, the present application obtains the transmitted optical signal and the laser signal, performs polarization rotation and beam splitting on the laser signal, and finally combines the bias amount to accurately adjust the phase of the laser to ensure that the laser signal and the optical signal transmitted by the optical fiber link always maintain phase synchronization during the beat frequency process. This greatly improves the stability of the optical frequency signal, and because the phase synchronization of the laser signal and the transmitted optical signal can be maintained continuously and stably, it helps to extend the stable transmission distance of the optical signal in the optical fiber.

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0024] See also Figure 1 , which is a flow chart of a method for suppressing polarization changes in an optical frequency signal beat process provided by an embodiment of the present application, such as Figure 1 As shown, the method for suppressing polarization change during the optical frequency signal beat process may include steps S101-S105: S101: Acquire laser signals and transmit optical signals.

[0025] At the beginning of the entire phase difference adjustment process, two optical signals need to be obtained first: laser signal and transmission optical signal. The laser signal is generated and emitted by the laser, while the transmission optical signal is sent through the optical fiber link. The transmission optical signal is the optical signal that will beat with the laser signal during the relay process, user use process or out-of-loop evaluation process.

[0026] S102: Perform polarization rotation on the laser signal to obtain a rotated laser signal.

[0027] After obtaining the laser signal and transmitting the optical signal, the laser signal can be polarized and rotated, that is, its polarization direction is changed 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 needs of the system. Through optical beam splitting and polarization rotation, the propagation characteristics of the laser signal can be precisely controlled and adjusted.

[0028] It should be noted that the polarization rotation of the laser signal can be achieved by rotating a Faraday rotator, and the angle of polarization rotation can be, but is not limited to, 45 degrees.

[0029] In one possible implementation, if the laser signal needs to be transmitted to the next level or user, a beam splitter can be used to split the laser signal to obtain two identical laser signals, one of which is transmitted to the next level or user, and the other is used for polarization rotation to obtain a rotated laser signal.

[0030] 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 beams of light with a certain ratio.

[0031] S103: 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.

[0032] The rotating laser signal is subjected to polarization splitting processing to separate it into two optical signals with different polarization directions, and obtain a first horizontally polarized optical signal and a first vertically polarized optical signal. At the same time, a similar polarization splitting operation is performed on the transmission optical signal to separate it into two optical signals with different polarization directions, and obtain a second horizontally polarized optical signal and a second vertically polarized optical signal. Through this polarization splitting method, each optical signal can be separated according to its polarization direction for subsequent signal processing and analysis.

[0033] It should be noted that the polarization splitting of the rotating laser signal and the transmitting optical signal can be achieved by a polarizing beam splitter (PBS).

[0034] S104: Perform 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.

[0035] Based on four polarized light signals - the first horizontal polarized light signal, the second horizontal polarized light signal, the first vertical polarized light signal and the second vertical polarized light signal, a series of processing steps are performed, including orthogonal beat frequency, photoelectric demodulation, power detection and phase detection, so as to obtain the first voltage, the second voltage, the first error and the second error. Specifically, the first voltage is obtained by orthogonal beat frequency and photoelectric demodulation of the first horizontal polarized light signal and the second horizontal polarized light signal. The second voltage is obtained by performing the same processing steps on the first vertical polarized light signal and the second vertical polarized light signal. These steps are intended to extract key voltage and error information through precise signal processing technology for subsequent phase adjustment.

[0036] See also Figure 2 , Figure 2 A method flow chart of a signal processing method provided in an embodiment of the present application. Accordingly, step S104 performs 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, which can be specifically implemented by steps A1-A3: A1: performing orthogonal beat frequency processing on the first horizontally polarized light signal and the second horizontally polarized light signal to obtain a horizontal beat frequency signal, and performing orthogonal beat frequency processing on the first vertically polarized light signal and the second vertically polarized light signal to obtain a vertical beat frequency signal.

[0037] In order to obtain the first voltage, the second voltage, the first error and the second error, the two different polarized light signals may be subjected to orthogonal beat frequency processing. Specifically, the first horizontally polarized light signal and the second horizontally polarized light signal are first subjected to orthogonal beat frequency processing (i.e., the frequency difference between the two signals is amplified by a specific mathematical or physical method), thereby obtaining a new signal, namely, a horizontal beat frequency signal.

[0038] Similarly, in the second step, the first vertical polarized light signal and the second vertical polarized light signal are processed in the same way to obtain a vertical beat signal. In this way, by means of orthogonal beat frequency, signals with different polarization directions can be processed separately for subsequent signal analysis and processing.

[0039] A2: 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 photoelectric demodulation on the vertical beat frequency signal to obtain a first vertical radio frequency signal and a second vertical radio frequency signal.

[0040] The purpose of performing photoelectric demodulation on the beat frequency signal is to convert the optical signal into an electrical signal. Specifically, for the horizontal beat frequency signal obtained previously, two different electrical signals are extracted through the photoelectric demodulation process, which are respectively called the first horizontal radio frequency signal and the second horizontal radio frequency signal.

[0041] Similarly, by performing photoelectric demodulation on the vertical beat frequency signal, two electrical signals are obtained, namely a first vertical radio frequency signal and a second vertical radio frequency signal. These radio frequency signals are the results of photoelectric demodulation and contain the frequency information of the original optical signal.

[0042] It should be noted that the photoelectric demodulation of the horizontal beat signal and the vertical beat signal can be achieved by using a photoelectric detector.

[0043] A3: Perform the power detection on the first horizontal RF signal and the first vertical RF signal to obtain a first voltage and a second voltage, and perform the phase detection on the second horizontal RF signal and the second vertical RF signal in combination with the RF reference signal to obtain a first error and a second error.

[0044] Finally, the first horizontal RF signal and the first vertical RF signal are power-detected to obtain the first voltage and the second voltage. Combined with the RF reference signal, the second horizontal RF signal and the second vertical RF signal are phase-detected to obtain the first error and the second error. Specifically, power detection is used to measure the strength of the RF signal and convert it into a corresponding voltage value; while phase detection calculates the corresponding error value by comparing the phase difference between the RF signal and the reference signal. These steps are designed to extract and quantify the key parameters of the RF signal and provide basic data for subsequent signal processing and analysis.

[0045] It should be noted that the RF reference signal is a standard RF signal used to provide a reference phase or frequency for comparison and calibration with other RF signals. In the above process, the role of the RF reference signal is: Phase detection reference: By comparing the second horizontal RF signal and the second vertical RF signal with the RF reference signal, the phase offset of these signals relative to the reference signal can be accurately measured to obtain the first error and the second error.

[0046] Ensure accuracy: Using an RF reference signal ensures accurate and consistent phase detection, making signal processing results more reliable.

[0047] Specifically, when performing phase detection, the RF reference signal is used as a known standard phase to determine the phase difference of the signal to be tested relative to the standard signal. In this way, the phase deviation between the signals can be accurately quantified and corrected, thereby achieving precise phase synchronization and adjustment.

[0048] 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 implemented by a power detector.

[0049] In a possible implementation manner, in step A1, the phase detection is performed on the second horizontal RF signal and the second vertical RF signal in combination with the RF reference signal to obtain the first error and the second error, which specifically includes the following two steps: (1) Calculate the phase difference between the second horizontal RF signal and the RF reference signal: The second horizontal radio frequency signal is compared with the radio frequency reference signal, and the phase difference between the two is calculated to obtain a first error. The first error represents the phase deviation of the second horizontal radio frequency signal relative to the radio frequency reference signal.

[0050] (2) Calculate the phase difference between the second vertical RF signal and the RF reference signal: The second vertical radio frequency signal is compared with the radio frequency reference signal, and the phase difference between the two is calculated to obtain a second error. The second error represents the phase deviation of the second vertical radio frequency signal relative to the radio frequency reference signal.

[0051] Through these two steps, the phase deviations of the second horizontal RF signal and the second vertical RF signal relative to the RF reference signal, i.e., 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 and the transmitted optical signal in the optical fiber link maintain phase synchronization at the beat frequency.

[0052] S105: Combining the first voltage, the second voltage, the first error, the second error and the offset, phase-adjust 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.

[0053] The working state of the laser is adjusted by comprehensively considering multiple factors, that is, the phase of the laser is adjusted using the first voltage, second voltage, first error, second error and offset obtained previously. 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 offset is a value calculated from the difference between the first error and the second error. With these data, the laser can be accurately adjusted to ensure that the laser signal emitted by the laser and the optical signal transmitted in the optical fiber link maintain phase consistency at the beat frequency (i.e., the frequency of phase synchronization), thereby ensuring the stability and accuracy of signal transmission.

[0054] See also Figure 3 , Figure 3 A method flow chart of a phase adjustment method provided in an embodiment of the present application. Accordingly, step S105 combines the first voltage, the second voltage, the first error, the second error and the offset to perform phase adjustment on 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, which can be specifically achieved through steps B1-B4: B1: Calculate the difference between the first error and the second error to obtain the offset.

[0055] 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) by comparing them. This difference, called the offset, represents the deviation of the system under the two error conditions. By calculating this difference, a correction can be obtained to help further adjust the phase of the laser so that it is more accurately synchronized with the signal transmitted by the optical fiber link. In short, the offset reflects the gap between the errors, is used to quantify the relative deviation between the two errors, and provides the necessary reference for subsequent adjustments.

[0056] B2: Determine an output error by combining the first voltage, the second voltage, the first error, the second error, and the offset.

[0057] “Determining the output error by combining the first voltage, the second voltage, the first error, the second error and the offset” means: calculating a final output error by comprehensively considering multiple factors (including the first voltage, the second voltage, the first error, the second error and the offset).

[0058] 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 offset to obtain the output error. The purpose of this process is to select the appropriate error value for correction based on the voltage relationship and the different error conditions, thereby ensuring the accuracy and stability of phase adjustment.

[0059] B3: Perform proportional-integral adjustment on the output error to obtain a servo control signal.

[0060] 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.

[0061] Specifically, first of all, the output error refers to the gap between the current state of the system and the desired target, which is usually a real-time feedback signal used to reflect the deviation of the system. In order to make the system reach the target state, we need to make appropriate adjustments based on this error. Proportional-integral regulation (PI) is a control method that combines two different control methods: Proportional control (P): Proportional control is adjusted according to the current error. The larger the error, the greater the adjustment of the control signal. In this way, proportional control can respond quickly to the error and reduce the deviation of the system.

[0062] Integral regulation (I): Integral control is based on the accumulation of errors over a period of time, that is, taking into account the persistence and historical impact of the errors. Through the integral action, the system can correct small errors that exist for a long time, ensuring that even long-term deviations can be corrected, thereby avoiding the system from deviating from the target for a long time.

[0063] 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 it emits and the transmitted optical signal emitted by the optical fiber link maintain phase synchronization at the beat frequency.

[0064] B4: adjusting 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.

[0065] By applying a servo control signal, the phase of the laser signal emitted by the laser can be adjusted to ensure that the laser signal maintains phase synchronization with the optical signal transmitted by the optical fiber link at the beat frequency.

[0066] 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 laser's output signal (i.e., the time delay or angle of the signal) so that the phase relationship between the laser signal and the optical signal transmitted by the optical fiber link reaches the desired state.

[0067] In fiber optic communications or laser systems, beat frequency refers to the periodic change in the phase difference between two signals of different frequencies when they interact with each other, forming a low-frequency signal. If the phases of the laser signal and the transmission signal are not synchronized, their beat frequency will be disturbed, which may affect the stability of the signal and the transmission quality. Therefore, in order to ensure the transmission quality of the signal, the output phase of the laser can be adjusted using a servo control signal to synchronize the phase of the laser signal with the signal transmitted by the optical fiber link, thereby keeping the beat frequency stable and ensuring accurate signal transmission.

[0068] Based on the contents of S101-S105, it can be known that first, a laser signal is obtained from the laser, and a transmission light signal that beats with it is obtained through an optical fiber link. Next, the laser signal is optically split and a rotated laser signal is obtained through polarization rotation, and then the rotating laser signal is polarized and split with the polarization of the transmission light signal to obtain four light signals with different polarization states. Through orthogonal beat frequency, photoelectric demodulation, power detection and phase detection, a first voltage, a second voltage, a first error and a second error are obtained. Finally, based on these voltages and error signals, the bias is calculated and the phase of the laser is adjusted to ensure that the laser signal and the transmission light signal always maintain phase synchronization during the beat process. This application uses orthogonal beat frequency, photoelectric demodulation and phase detection technologies to deeply analyze the polarized light signal, and adjusts the bias according to the error to compensate for the change in polarization state caused by the birefringence effect and reduce the impact of polarization instability. By acquiring laser signals and transmitting optical signals, performing polarization rotation and beam splitting, and combining the bias amount to accurately adjust the phase of the laser, it is ensured that the phase of the optical signal and the laser signal are synchronized during the beat 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.

[0069] See also Figure 4 , Figure 4 This is a schematic diagram of the structure of a device for suppressing polarization changes in the process of optical frequency signal beat frequency provided by an embodiment of the present application. Figure 4 As shown, the polarization change suppression device in the optical frequency signal beat process includes: The acquisition unit 401 is used to 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; and the laser signal is emitted by a laser. A polarization rotation unit 402, configured to perform polarization rotation on the laser signal to obtain a rotated laser signal; A polarization beam splitting unit 403, 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; The integration unit 404 is used 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; The first phase adjustment unit 405 is used to perform phase adjustment on the laser in combination with the first voltage, the second voltage, the first error, the second error and the offset, 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.

[0070] In a possible implementation, the integration unit 404 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.

[0071] In a possible implementation, the first phase adjustment unit 405 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.

[0072] In a possible implementation manner, the output error determination unit is specifically used to: 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.

[0073] In a possible implementation manner, the phase detection unit specifically includes: A first error calculation unit, configured to calculate a phase difference between the second horizontal RF signal and the RF reference signal to obtain a first error; The second error calculation unit is used to calculate the phase difference between the second vertical RF signal and the RF reference signal to obtain a second error.

[0074] In addition, an embodiment of the present application also provides a device for suppressing polarization changes in the beat process of an optical frequency signal, including: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the method for suppressing polarization changes in the beat process of an optical frequency signal as described above is implemented.

[0075] In addition, an embodiment of the present application further provides a computer-readable storage medium, in which instructions are stored. When the instructions are executed on a terminal device, the terminal device executes the method for suppressing polarization changes in the beat process of an optical frequency signal as described above.

[0076] The embodiment of the present application provides a device for suppressing polarization changes during the beat process of an optical frequency signal. First, the acquisition unit 401 is used to acquire a laser signal and a transmission optical signal, and the polarization rotation unit 402 is used to polarize the laser signal to obtain a rotated laser signal. The polarization splitting unit 403 performs polarization splitting on the rotated laser signal to obtain a first horizontally polarized light signal and a first vertically polarized light signal, and performs polarization splitting on the transmission optical signal to obtain a second horizontally polarized light signal and a second vertically polarized light signal. Then, the integration unit 404 performs 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, so that the first phase adjustment unit 405 can combine 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 during the beat frequency. This application uses orthogonal beat frequency, photoelectric demodulation and phase detection technology to conduct in-depth analysis of polarized light signals, and compensates for the change in polarization state caused by the birefringence effect by adjusting the bias, thereby reducing the impact of polarization instability. At the same time, by acquiring the transmitted light signal and laser signal, the laser signal is polarized and split, and the laser is precisely phase-adjusted in combination with the bias, ensuring that the laser signal and the light signal transmitted by the optical fiber link maintain phase synchronization during the beat frequency process, greatly improving the stability of the optical frequency signal. This continuous and stable phase synchronization characteristic helps to extend the stable transmission distance of the optical signal in the optical fiber.

[0077] The above is a detailed introduction to a method for suppressing polarization changes in the beat frequency process of an optical frequency signal and related devices provided by the present application. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced 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 method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0078] It should be understood that in this application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: 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.

[0079] It should also be noted that, in this article, relational terms such as first and second, etc. 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 "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

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.

2. The method according to claim 1, characterized in that 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.

3. 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.

4. The method according to claim 3, 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.

5. The method according to claim 2, 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.

6. A device for suppressing polarization change during the beat 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 is used 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 transmitted light signal emitted by the optical fiber link maintain phase synchronization at the beat frequency; the offset is a deviation value between the first error and the second error.

7. The device according to claim 6, characterized in that 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.

8. The device according to claim 6, 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.

9. A device for suppressing polarization changes during the beat 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 during the beat process of an optical frequency signal as described in any one of claims 1 to 5 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 method for suppressing polarization changes in an optical frequency signal beat process as described in any one of claims 1 to 5.

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