Method and apparatus for improving polarization tracking speed

Abstract

The present application relates to the technical field of optical fiber communication, and provides a method and device for improving polarization tracking speed. The present application controls a polarization controller to track polarization light randomly disturbed by different disturbance speeds; according to feedback light intensity of the polarization controller, the phase shift amount of a phase shifter in the polarization controller is first adjusted according to a specified step length iteration until the feedback light intensity tends to zero, and then the optimal phase modulation speed adapted by the polarization controller is determined; then the polarization light randomly disturbed by different disturbance speeds is tracked according to the optimal phase modulation speed, the step length modulation factor of a variable step length control model is used to make the feedback light intensity tend to zero, the control parameters of the variable step length control model are determined, and the purpose of improving the tracking speed by using the optimal phase modulation speed and the control parameters is achieved. The present application solves the problem that the performance of the polarization controller in the prior art is limited by the control algorithm and the high-performance polarization controller at the hardware level cannot be well utilized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical fiber communication technology, in particular to a method and device for improving polarization tracking speed. BACKGROUND

[0002] High-speed optical fiber communication has realized important functions such as large server cluster and transoceanic communication, and has become an important foundation of modern society, and is developing towards miniaturization and integration. However, in a communication system, stress, movement and vibration on an optical fiber will cause fluctuations in the polarization state of light, causing fluctuations in the polarization state of an optical signal, thereby causing random fluctuations in the intensity and phase of a modulated signal.

[0003] Therefore, a polarization controller is used to constantly change the phase shift of each phase modulation unit according to the randomly changing input polarization state, so as to output the polarization state at a certain specific polarization state, thereby reducing the fluctuations in the polarization state of the optical signal as much as possible. The main indicators of polarization control are tracking speed and tracking accuracy. The response speed and accuracy of the phase modulation unit limit the tracking speed and tracking accuracy. With the gradual replacement of the mechanical extrusion type unit by various high-performance integrated optical devices, the tracking speed has been rapidly improved, and the factors limiting polarization stabilization and affecting tracking speed have gradually shifted from hardware to control algorithms.

[0004] At present, many polarization controllers can achieve nanosecond-level response, however, the overall polarization tracking effect of such polarization controllers is limited to 10Krad / s to 100Krad / s, which is a great waste of the rapid response performance of the polarization controller at the hardware level.

[0005] Therefore, there is an urgent need for a solution that improves the performance utilization of the polarization controller by improving the coordination between the polarization controller and the polarization control algorithm, thereby breaking through the bottleneck of polarization tracking speed.

[0006] In view of this, overcoming the defects of the prior art is a problem that urgently needs to be solved in the technical field. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a method and device for improving polarization tracking speed, which aims to determine the optimal phase modulation speed by iteratively adjusting the phase shift of the phase shifter in the polarization controller, to improve the adaptation of the polarization control algorithm to the polarization controller, and thereby improve the effect of polarization control, solving the problem that the performance of the polarization controller is limited by the control algorithm in the prior art, and the high-performance polarization controller at the hardware level cannot be well utilized.

[0008] The present application adopts the following technical solutions:

[0009] In a first aspect, the present application provides a method for improving the speed of polarization tracking, comprising:

[0010] controlling the polarization controller to track the randomly disturbed polarized light with different disturbance speeds; adjusting the phase shift of the phase shifter in the polarization controller according to the feedback light intensity of the polarization controller and a specified step size, until the feedback light intensity tends to zero; determining the optimal phase adjustment speed adapted by the polarization controller;

[0011] controlling the polarization controller to track the randomly disturbed polarized light with different disturbance speeds according to the optimal phase adjustment speed; adjusting the phase shift of the phase shifter in the polarization controller according to the feedback light intensity of the polarization controller and a step size modulation factor through a variable step size control model, until the feedback light intensity tends to zero, obtaining the control parameters of the variable step size control model, so that the polarization controller uses the optimal phase adjustment speed and the control parameters for tracking.

[0012] Further, the adjusting the phase shift of the phase shifter in the polarization controller according to the feedback light intensity of the polarization controller and a specified step size, until the feedback light intensity tends to zero comprises:

[0013] for each phase shifter in the polarization controller, increasing or decreasing the phase shift of the phase shifter by a specified step size based on the corresponding feedback light intensity, to adjust the phase shift of the phase shifter in the corresponding iteration direction;

[0014] the polarization controller updates the feedback light intensity according to the adjusted phase shift;

[0015] comparing the updated feedback light intensity with the updated feedback light intensity, and determining the iteration direction of the next adjustment of the phase shift of the phase shifter according to the comparison result;

[0016] iterating the above process until the feedback light intensity of the polarization controller tends to zero.

[0017] Further, the determining the optimal phase adjustment speed adapted by the polarization controller comprises:

[0018] recording the phase adjustment speed of the phase shifter and the corresponding tracking speed of the polarization controller in each iteration process;

[0019] comparing the tracking speeds of the polarization controller at different phase adjustment speeds to determine the mapping relationship between the phase adjustment speed and the tracking speed;

[0020] obtaining the optimal phase adjustment speed adapted by the polarization controller based on the mapping relationship.

[0021] Further, the mapping relationship between the phase modulation speed and the tracking speed is determined by comparing the tracking speeds of the polarization controller at different phase modulation speeds, comprising:

[0022] The polarization controller tracks the randomly scrambled polarized light at different phase modulation speeds and different disturbance speeds; the relative intensity difference of each iteration is determined, and the relative intensity difference at the same disturbance speed is taken as the same group of sample data; wherein the expression of the relative intensity difference is: I FB I is the feedback light intensity, OUT I is the output light intensity of the polarization controller;

[0023] According to the multiple groups of sample data, the complementary cumulative distribution is calculated; and according to the multiple groups of sample data and the corresponding complementary cumulative distribution, the relative intensity difference curve is constructed.

[0024] The relative intensity difference curves at different phase modulation speeds are compared when tracking, and when the relative intensity difference of the polarization controller within a preset time is less than a preset value, the mapping relationship is obtained.

[0025] Further, the calculation of the complementary cumulative distribution according to the multiple groups of sample data comprises:

[0026] The first sample number of each group of sample data is obtained; and the second sample number of the relative intensity difference less than the intensity difference threshold in each group of sample data is obtained.

[0027] The ratio of the second sample number to the first sample number is determined as the cumulative distribution value F(RIE);

[0028] According to all the complementary cumulative distribution values 1-F(RIE) corresponding to the multiple groups of sample data, the complementary cumulative distribution of the multiple groups of sample data is obtained.

[0029] Further, in the iteration process, further comprising:

[0030] The clock division multiple of the polarization controller for tracking is adjusted, so that the waiting response time of the polarization controller is the shortest, so as to improve the tracking speed of the polarization controller;

[0031] The waiting response time is: the time when the phase shift of the phase shifter in the current iteration is adjusted to the time when the adjusted phase shifter responds to the adjustment.

[0032] Further, the polarization controller is controlled to track the randomly scrambled polarized light at different disturbance speeds according to the optimal phase modulation speed; and the phase shift of the phase shifter in the polarization controller is iteratively adjusted according to the feedback light intensity of the polarization controller and the step length modulation factor through a variable step length control model, comprising:

[0033] In each iteration process, for each phase shifter in the polarization controller, the phase shift of the phase shifter is increased or decreased by a current step based on the corresponding feedback light intensity, so as to adjust the phase shift of the phase shifter in a corresponding iteration direction;

[0034] The polarization controller updates the feedback light intensity according to the adjusted phase shift; compares the updated feedback light intensity with the updated feedback light intensity before the adjustment; and determines the iteration direction for adjusting the phase shift of the phase shifter in the next iteration according to the comparison result.

[0035] The polarization controller obtains output light according to the adjusted phase shift; determines a step modulation factor of the current iteration according to the output light; and updates the current step for the next iteration according to the step modulation factor of the current iteration.

[0036] Further, the determination of the step modulation factor of the current iteration according to the output light comprises:

[0037] determining a current state point of the output light on a Poincare sphere, determining a target point of the polarization state of the output light on the Poincare sphere, and determining an adjustment reference distance between the current state point and the target point;

[0038] when the adjustment reference distance is greater than a feedback light threshold, determining a first multiple value as the step modulation factor; and when the adjustment reference distance is less than or equal to the feedback light threshold, determining a second multiple value as the step modulation factor; wherein the first multiple value is greater than the second multiple value.

[0039] Further, the Jones matrix of the phase shifter is:

[0040]

[0041] wherein, is the phase shift of the phase shifter, and j is the imaginary part of a complex number;

[0042] The Jones matrix of the coupler in the polarization controller is:

[0043]

[0044] The phase shifters and the couplers are alternately arranged and combined to form the polarization controller; when the polarization controller is a two-stage phase modulation structure, the Jones matrix of the polarization controller is:

[0045]

[0046] wherein, E OUT represents the output light intensity of the polarization controller, E FB represents the feedback light intensity of the polarization controller, and E xrepresents the light intensity of the incident light X direction polarization, E y represents the light intensity of the incident light Y direction polarization, represents the phase shift amount of the first stage phase shifter of the polarization controller, represents the phase shift amount of the second stage phase shifter of the polarization controller.

[0047] In a second aspect, the application further provides a device for improving the polarization tracking speed, which is used to implement the method for improving the polarization tracking speed in the first aspect, and comprises a laser, a polarization scrambler, a polarization controller and a control unit.

[0048] The laser is configured to generate an original light source.

[0049] The polarization scrambler is configured to randomly scramble the original light source at different polarization scrambling speeds to obtain corresponding polarized light.

[0050] The control unit is configured to control the polarization controller to track the polarized light randomly scrambled at different polarization scrambling speeds, to iteratively adjust the phase shift amount of the phase shifter in the polarization controller according to the feedback light intensity of the polarization controller at a specified step length until the feedback light intensity tends to zero, to determine an optimal phase modulation speed adapted by the polarization controller, and to control the polarization controller to track the polarized light randomly scrambled at different polarization scrambling speeds according to the optimal phase modulation speed, and to iteratively adjust the phase shift amount of the phase shifter in the polarization controller according to the feedback light intensity of the polarization controller and a step length modulation factor through a variable step length control model until the feedback light intensity tends to zero to obtain a control parameter of the variable step length control model.

[0051] The polarization controller is configured to track the polarized light randomly scrambled at different polarization scrambling speeds.

[0052] In an optional embodiment, the control unit comprises:

[0053] at least one processor, and a memory connected with the at least one processor in communication, wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the processor to implement the method for improving the polarization tracking speed in the first aspect.

[0054] In a third aspect, the application further provides a non-volatile computer storage medium, which stores computer executable instructions, and the computer executable instructions are executed by one or more processors to complete the method for improving the polarization tracking speed in the first aspect.

[0055] In a fourth aspect, a chip is provided, which comprises a processor and an interface, and is configured to call and run a computer program stored in a memory to implement the method for improving the polarization tracking speed in the first aspect.

[0056] In a fifth aspect, a computer program product containing instructions, which, when executed on a computer or processor, cause the computer or processor to perform the method for improving polarization tracking speed according to the first aspect to the fourth aspect and any one of them.

[0057] In a sixth aspect, a method system for improving polarization tracking speed is provided, which comprises the device for improving polarization tracking speed according to the second aspect and uses the method for improving polarization tracking speed according to the first aspect to complete the interaction of the device for improving polarization tracking speed according to the second aspect.

[0058] Compared with the prior art, the present application has at least the following beneficial effects:

[0059] The present application controls the polarization controller to track the polarization light randomly disturbed by different disturbance speeds; according to the feedback light intensity of the polarization controller, the phase shift amount of the phase shifter in the polarization controller is first adjusted according to a specified step length iteration, until the feedback light intensity tends to zero, and then the optimal phase adjustment speed adapted by the polarization controller is determined; then the polarization light randomly disturbed by different disturbance speeds is tracked according to the optimal phase adjustment speed, the step length modulation factor of the variable step length control model is used to make the feedback light intensity tend to zero, the control parameters of the variable step length control model are determined, and the purpose of improving the tracking speed by using the optimal phase adjustment speed and the control parameters is achieved. Wherein, the present application determines the optimal phase adjustment speed by iteratively adjusting the phase shift amount of the phase shifter in the polarization controller, optimizes the phase adjustment speed to improve the adaptation degree of the control algorithm and the polarization controller, improves the tracking speed of the polarization controller, and solves the problem that the performance of the polarization controller in the prior art is limited by the control algorithm, and the high-performance polarization controller at the hardware level cannot be well utilized. BRIEF DESCRIPTION OF DRAWINGS

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained according to these drawings without creative labor for those skilled in the art.

[0061] Figure 1 is a flowchart of a method for improving polarization tracking speed provided by an embodiment of the present application;

[0062] Figure 2 is a schematic diagram of a four-stage silicon-based thermal phase shifter structure provided by an embodiment of the present application;

[0063] Figure 3 is a flowchart of step 10 provided by an embodiment of the present application;

[0064] Figure 4is a flowchart of step 10 provided by an embodiment of the present application;

[0065] Figure 5 is a complementary cumulative distribution diagram of main clock 800 division provided by an embodiment of the present application;

[0066] Figure 6 is a complementary cumulative distribution diagram of main clock 1600 division provided by an embodiment of the present application;

[0067] Figure 7 is a complementary cumulative distribution diagram of main clock 800 division provided by an embodiment of the present application;

[0068] Figure 8 is a flowchart of step 20 provided by an embodiment of the present application;

[0069] Figure 9 is a perturbation trajectory diagram using fixed step length algorithm provided by an embodiment of the present application;

[0070] Figure 10 is a control effect diagram using fixed step length algorithm provided by an embodiment of the present application;

[0071] Figure 11 is a perturbation trajectory diagram using variable step length algorithm provided by an embodiment of the present application;

[0072] Figure 12 is a control effect diagram using variable step length algorithm provided by an embodiment of the present application;

[0073] Figure 13 is a device diagram for improving polarization tracking speed provided by an embodiment of the present application;

[0074] Figure 14 is a control unit architecture diagram provided by an embodiment of the present application. DETAILED DESCRIPTION

[0075] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0076] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0077] Unless otherwise required by context, as used herein the term "comprising" is to be interpreted as open-ended, i.e. as "including but not limited to". In describing the disclosure, the terms "one embodiment", "some embodiments", "an exemplary embodiment", "an example", "a specific example" or "some examples" are intended to mean that a particular feature, structure, material, or characteristic is included in at least one embodiment or example of the present disclosure. These terms are not necessarily intended to refer to the same embodiment or example. Furthermore, these terms can refer to a single embodiment or example or multiple embodiments or examples occurring in either a single application or multiple applications. Thus, in the description, these terms are used in a way to mean that a particular feature, structure, material, or characteristic is included in at least one embodiment or example of the disclosure, but is not necessarily included in all embodiments or examples of the disclosure.

[0078] In the description of the present disclosure, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the purpose of facilitating the description of the present disclosure and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present disclosure.

[0079] In the description of the present disclosure, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise stated, the meaning of "a plurality of" is two or more. In addition, for example, in the description, the same type of nouns can also be described as two independent individuals by adding "A", "B" at the end, in which case the features limited by "A", "B" are only for the purpose of distinguishing the same type of individual description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

[0080] In describing some embodiments, the use of "coupled" or "coupling" and "connected" or "connecting" along with their derivatives, can be used. For example, some embodiments can be described as connected to each other when the two or more components are in direct physical or electrical contact with each other. As another example, some embodiments can be described as coupled to each other when the two or more components are in direct physical or electrical contact with each other, or when the two or more components are not in direct contact with each other, but are still in cooperation, communication, or interoperability with each other. The embodiments disclosed herein are not necessarily limited in terms of the manner in which the components are coupled or connected together.

[0081] In the description of the application, the expression "A and / or B" (wherein A and B represent specific features) is used in the sense that the expression includes the following three combinations: A alone, B alone, and A and B together.

[0082] As used herein, "about," "approximately," or "substantially" with reference to a stated value includes the stated value and the average value within an acceptable range of deviation from the stated value, as determined by one of ordinary skill in the art considering the measurement at issue and the error (i.e., limitations in the measurement system) associated with the measurement of the particular quantity.

[0083] Example 1:

[0084] The polarization control process can be described using a Poincare sphere as follows: a polarization controller outputs a stabilized polarization state at a point on the surface of the Poincare sphere from an input polarization state that is randomly moving on the surface of the Poincare sphere. Due to the carrier fading phenomenon caused by the random fluctuation of the local oscillator polarization state in a coherent optical communication system, a polarization controller is needed to track the polarization state. However, in a harsh environment, such as lightning, the polarization state in the optical fiber can rotate at a speed of Mrad / s, and therefore a high-speed automatic polarization controller is of great significance. In recent years, thin-film lithium niobate polarization controllers have attracted widespread attention from researchers due to their ultrafast electro-optic response speed.

[0085] With the gradual replacement of high-performance integrated optical devices such as silicon-based phase modulation units and lithium niobate type phase modulation units for the past mechanical extrusion type units, the polarization tracking speed is rapidly improved, and the tracking speed is gradually not limited by hardware factors. The factors limiting the tracking speed are more for the control algorithm. For example, many lithium niobate polarization controllers can reach nanosecond-level response at present. However, although the response time of the lithium niobate polarization controller reaches the nanosecond level, the polarization tracking rate of the overall lithium niobate polarization controller is still limited to 10Krad / s to 100Krad / s. The reason is still that the circuit and the control algorithm are not well adapted to the polarization controller. This is a great waste of the fast response performance of the lithium niobate polarization controller at the hardware level.

[0086] To solve the above problems, as shown in the Figure 1 The embodiment of the application provides a method for improving polarization tracking speed, which comprises the following steps:

[0087] Step 10: controlling the polarization controller to track the polarization light randomly disturbed by different polarization disturbance speeds; according to the feedback light intensity of the polarization controller, the phase shift amount of the phase shifter in the polarization controller is iteratively adjusted according to a specified step size until the feedback light intensity tends to zero; and the optimal phase modulation speed adapted by the polarization controller is determined.

[0088] Wherein, the state represented by the feedback light intensity tending to zero is s1=±1; wherein, s1=±1 represents the position of the polarization state on the Poincare sphere, and the position can only be +1 or -1, and cannot be locked at ±1 at the same time. The specified step size is a fixed value, which is selected by a person skilled in the art according to the specific use scene. The optimal phase modulation speed is the fastest phase modulation speed adapted by the polarization controller for tracking.

[0089] The use scene of the method for improving polarization tracking speed of the embodiment of the application is described below:

[0090] The ultimate goal of the embodiment of the application is to find the related parameters that make the specified polarization controller reach the fastest tracking speed; and in the subsequent use of the polarization controller, after inputting the polarization light of any polarization state, the tracking is performed according to the determined related parameters, and the tracking speed can reach the fastest tracking speed.

[0091] The embodiment of the application achieves the ultimate goal by performing polarization light tracking experiments through multiple iterations. Since the factors affecting the polarization tracking speed are mainly the phase modulation speed and the parameters for controlling the polarization controller to track, the process of achieving the ultimate goal of the embodiment of the application is divided into two stages: first, the optimal phase modulation speed is determined, and then the parameters for tracking are determined.

[0092] In both stages of the polarization tracking experiment, randomly scrambled polarized light is input into a polarization controller, which tracks the input polarized light and iteratively adjusts the phase shift of the phase shifter during the tracking process. Each time, the polarization controller stabilizes the polarization state of the input polarized light at a specific polarization state, outputting a portion of the stabilized polarized light as feedback light and the remaining portion directly as output light. The iteration stops when the intensity of the feedback light approaches zero, completing the tracking of the input polarized light.

[0093] In an alternative embodiment, the polarization controller may be an adaptive polarization controller that includes multiple stages of phase shifters, such as a four-stage silicon-based thermal phase shifter.

[0094] like Figure 2 As shown, a polarization controller is provided, which includes a polarization splitter rotator (PSR) and multiple 3dB couplers (i.e., Figure 2 The diagram shows a 3dB phase shifter (PS) structure, multiple drivers, and a photodiode (PD). The PSR is used to separate and convert the orthogonal components of arbitrary polarized light into specific polarization states; the multi-stage phase shifter structure consists of… Figure 2 The diagram shows phase shifters "PS1", "PS2", "PS3", and "PS4". A driver is used to control the phase shifters and other active devices (such as thermally modulated phase shifters). The driver receives signals from a Field Programmable Gate Array (FPGA) or other controller and converts them into current or voltage signals capable of driving the phase shifters and other devices. A photodiode (PD) is used to detect the feedback light intensity and convert this information into electrical signals for transmission.

[0095] Based on such Figure 2The polarization controller shown in the polarization light tracking experiment, the polarization controller input port PSR converts the input polarization light into X direction polarization state and Y direction polarization state of transverse electric (TE) mode; in the TE mode, the electric field is mainly located in the plane perpendicular to the light propagation direction, and there is no component perpendicular to the plane and the light propagation direction. The polarization light output by the PSR is divided into two parts, the input power of the input polarization controller is divided into two ways, one of which has the regulation of the phase shifter, forming a single arm Mach-Zehnder interferometer (MZI) structure, the overall effect is to convert the phase modulation into intensity modulation, and the interference is carried out in the 3dB coupler, and finally output by the last 3dB coupler; in the optional embodiment, 10% of the output of the last 3dB coupler is taken as the output light, and 90% is taken as the feedback light. And the embodiment of the application changes the additional phase of each phase shifter according to the intensity of the feedback light (i.e. feedback light intensity), so that the polarization state of the output light is TE mode and the light intensity is maximum.

[0096] In the process of determining the optimal phase modulation speed, the phase shift of the phase shifter to be adjusted is increased or decreased by a specified step iteratively, which will be described in detail below. The embodiment of the application adjusts the phase modulation speed in the polarization tracking algorithm, measures the influence of different phase modulation speeds on the polarization tracking effect, and optimizes the phase modulation speed to improve the polarization tracking speed from the level of the control algorithm.

[0097] Step 20: According to the optimal phase modulation speed, the polarization controller controls the polarization light with different disturbance speeds to be randomly scrambled; through the variable step control model, the phase shift of the phase shifter in the polarization controller is iteratively adjusted according to the feedback light intensity of the polarization controller and the step modulation factor, until the feedback light intensity tends to zero, and the control parameters of the variable step control model are obtained, so that the polarization controller uses the optimal phase modulation speed and the control parameters for tracking.

[0098] Wherein, the variable step control model is used to control the polarization tracking experiment of the polarization controller, and the control parameters of the variable step control model include the step modulation factor and other parameters.

[0099] The embodiment of the present application first determines the phase modulation speed of the two main factors affecting the tracking speed, and then controls the polarization controller to perform polarization tracking experiments according to the optimal phase modulation speed and the variable step control model. In the iteration process, the step length of the phase shift amount is dynamically adjusted based on the step length adjustment factor, so that the feedback light intensity can tend to zero faster at each iteration, and the fastest tracking speed of the polarization controller for different polarization states is obtained. The control parameters at the end of the iteration are used as the final determined control parameters, so that when the polarization controller is used subsequently, the optimal phase modulation speed and the control parameters of the final determined variable step control model are set, which can greatly improve the polarization tracking speed and achieve good polarization tracking effect.

[0100] The present application controls the polarization controller to track the polarization light randomly disturbed by different disturbance speeds. According to the feedback light intensity of the polarization controller, the phase shift amount of the phase shifter in the polarization controller is iteratively adjusted according to the specified step length until the feedback light intensity tends to zero, and the optimal phase modulation speed suitable for the polarization controller is determined. Then, the polarization light randomly disturbed by different disturbance speeds is tracked according to the optimal phase modulation speed, and the feedback light intensity tends to zero based on the step length modulation factor of the variable step control model to determine the control parameters of the variable step control model, achieving the purpose of improving the tracking speed using the optimal phase modulation speed and the control parameters. In the present application, the optimal phase modulation speed is determined by iteratively adjusting the phase shift amount of the phase shifter in the polarization controller, the adaptation of the control algorithm to the polarization controller is improved by optimizing the phase modulation speed, and the tracking speed of the polarization controller is improved, solving the problem that the performance of the polarization controller in the prior art is limited by the control algorithm and the high-performance polarization controller at the hardware level cannot be well utilized.

[0101] The method for improving the polarization tracking speed of the embodiment of the present application will be described in detail as follows:

[0102] Since the main factors limiting polarization stability and affecting tracking speed in the prior art are not hardware, but the control algorithm for controlling the polarization controller to track polarization, the embodiment of the present application determines the optimal phase modulation speed and the control parameters of the variable step control model, and uses them for tracking to simplify the complexity of the control algorithm, so that the adaptation of the control algorithm to the specified polarization controller can be improved, the tracking speed and the polarization control effect can be improved, and the problem of slow overall tracking speed and poor polarization control effect of the polarization controller in the prior art is solved.

[0103] First, the process of performing polarization tracking experiments will be described in detail with the determination of the optimal phase modulation speed as an example, as shown in FIG. 10. Figure 3 As shown in step 10, the phase shift amount of the phase shifter in the polarization controller is iteratively adjusted according to the specified step length based on the feedback light intensity of the polarization controller until the feedback light intensity tends to zero, which includes:

[0104] Step 101a: for each phase shifter in the polarization controller, increase or decrease the phase shift of the phase shifter by a specified step size based on the corresponding feedback light intensity, to adjust the phase shift of the phase shifter in the corresponding iteration direction.

[0105] Step 102a: the polarization controller updates the feedback light intensity according to the adjusted phase shift.

[0106] Step 103a: compare the updated feedback light intensity with the updated feedback light intensity, and determine the iteration direction of the next adjustment of the phase shift of the phase shifter according to the comparison result.

[0107] Step 104a: iterate the above process until the feedback light intensity of the polarization controller tends to zero.

[0108] wherein the Jones matrix of the phase shifter is:

[0109]

[0110] wherein, is the phase shift of the phase shifter, and j is the imaginary part of the complex number;

[0111] The Jones matrix of the coupler in the polarization controller is:

[0112]

[0113] The phase shifter and the coupler are alternately arranged and combined to form the polarization controller; when the polarization controller is a two-stage phase modulation structure, the Jones matrix of the polarization controller is:

[0114]

[0115] wherein, E OUT represents the output light intensity of the polarization controller, E FB represents the feedback light intensity of the polarization controller, E x represents the intensity of the light polarized in the X direction of the incident light, E y represents the intensity of the light polarized in the Y direction of the incident light, represents the phase shift of the first-stage phase shifter of the polarization controller, represents the phase shift of the second-stage phase shifter of the polarization controller.

[0116] For a single phase shifter, by increasing or decreasing its phase shift, and waiting for the response of the polarization controller, the feedback light intensity is measured at the feedback port, and according to the change of the feedback light intensity, the change direction of the phase shifter phase shift is changed. According to the tracking effect of the polarization controller on the randomly scrambled polarization state light of different perturbation speeds, the fastest tracking speed of the polarization controller is obtained.

[0117] For a single phase shifter, the optimization control of the tracking speed is achieved by iteration through the gradient descent algorithm, and the control process of the gradient descent algorithm is divided into four stages, which are as follows:

[0118] Stage 1: Obtain the current feedback light intensity, and increase or decrease a specified step of the phase shift amount;

[0119] Stage 2: Wait for the response of the phase shifter;

[0120] Stage 3: Obtain the current feedback light intensity, and compare it with the feedback light intensity in stage 1 to determine the direction of the next iteration;

[0121] Stage 4: Wait for the response of the phase shifter.

[0122] In each iteration process, according to the current feedback light intensity, one phase shifter in the polarization controller is adjusted, and after the polarization controller responds to this adjustment, the updated current feedback light intensity is compared with the feedback light intensity before updating to determine the direction of the next iteration (the iteration direction is to increase or decrease the phase shift amount), and the adjusted phase shifter is waited for response.

[0123] In an optional embodiment, for a polarization controller containing multiple stages (for example, four or more stages) of phase shifters, the above iteration process can be performed on one phase shifter in the polarization controller first, and then the above iteration process can be performed on other phase shifters in the polarization controller in turn to achieve a larger phase adjustment range.

[0124] The gradient descent algorithm of the embodiment of the application reduces the complexity of the control algorithm, focuses on the coordination of software and hardware, and reduces the difficulty of optimizing the speed of the polarization controller.

[0125] Through the four-stage silicon-based thermal phase shifter structure as shown in Figure 2 , a higher (100 Krad / s) tracking speed can be achieved, which is mainly limited by the response time of the thermal-optic effect, and the order of magnitude of the response time is microsecond level. In each iteration process, the loop delay T of the feedback loop of the polarization controller is S1+2×S2+2×S3+2×S4; wherein S1 represents the running and processing time of the control algorithm in the current iteration process; S2 represents the voltage rise time of the digital-to-analog converter and the amplification circuit on the control circuit board; S3 represents the conversion time of the photodetector, the transimpedance amplifier and the analog-to-digital converter; and S4 represents the response time of the control algorithm waiting for the response of the polarization controller. In an optional embodiment, the tracking speed can be further improved by reducing the response time, specifically, in the iteration process, it also includes:

[0126] The clock division multiple of the tracking of the polarization controller is adjusted to minimize the waiting response time of the polarization controller, so as to improve the tracking speed of the polarization controller; wherein the waiting response time is from the time of adjusting the phase shift of the phase shifter in the current iteration to the time of the adjusted phase shifter responding to the adjustment. For a specified polarization controller, by adjusting the running speed of the control algorithm, the running and processing time of the control algorithm in the current iteration process and the response time of the control algorithm to the polarization controller can be reduced, so as to increase the iteration number of the gradient descent algorithm in the same time, and then the fastest tracking speed of the polarization controller can be found faster.

[0127] In an alternative embodiment, as shown in Figure 2 , a polarization controller with a four-stage thermal phase shifter structure is used in hardware, and the control algorithm is implemented by FPGA. When the control algorithm is running on the FPGA, the response time of the polarization controller is adapted by adjusting the clock division multiple, so that the time of waiting for the response of the phase shifter in stages 2 and 4 of the gradient descent algorithm can be directly obtained and adjusted, and better tracking effect can be achieved.

[0128] According to the above steps, a polarization light tracking experiment is performed. In this process, in order to determine the optimal phase adjustment speed, as shown in Figure 4 , the determination of the optimal phase adjustment speed adapted by the polarization controller in step 10 comprises:

[0129] Step 101b: In each iteration process, the phase adjustment speed of the phase shifter and the corresponding tracking speed of the polarization controller are recorded.

[0130] Step 102b: The mapping relationship between the phase adjustment speed and the tracking speed is determined by comparing the tracking speeds of the polarization controller at different phase adjustment speeds.

[0131] Step 103b: Based on the mapping relationship, the optimal phase adjustment speed adapted by the polarization controller is obtained.

[0132] By adjusting the phase adjustment speed in the control algorithm, the influence of different phase adjustment speeds on the polarization tracking effect is measured. For example, the mapping relationship between the phase adjustment speed and the tracking speed can be that for 2 times of the phase adjustment speed, the tracking speed also reaches 2 times.

[0133] As shown in Figure 5 , the step 102b comprises:

[0134] Step 1021: The polarization controller is used to track the polarization light randomly disturbed by different disturbance speeds at different phase adjustment speeds; the relative intensity difference of each iteration is determined, and the relative intensity differences at the same disturbance speed are taken as the same group of sample data; wherein the expression of the relative intensity difference is: I FB I is the feedback light intensity, OUT I is the output light intensity of the polarization controller.

[0135] Step 1022: calculating a complementary cumulative distribution according to the multiple sets of sample data; and constructing a relative intensity error curve according to the multiple sets of sample data and the corresponding complementary cumulative distributions.

[0136] The evaluation criterion of the polarization control in the embodiment of the application adopts a relative intensity error (RIE) and a complementary cumulative distribution.

[0137] The complementary cumulative distribution is a probability of a specified relative intensity error being worse than its corresponding relative intensity error. A first sample quantity of each set of sample data is obtained; a second sample quantity of the each set of sample data, in which the relative intensity error is less than an intensity error threshold, is obtained; a ratio of the second sample quantity to the first sample quantity is determined as a cumulative distribution value F(RIE); and a complementary cumulative distribution of the multiple sets of sample data is obtained according to all the complementary cumulative distribution values 1-F(RIE) corresponding to the multiple sets of sample data.

[0138] Step 1023: comparing the relative intensity error curves when tracking at different phase modulation speeds, and obtaining the mapping relationship when the relative intensity error of the polarization controller is less than a preset value within a preset time.

[0139] The preset time and the preset value are selected by a person skilled in the art according to a specific use scenario, and are not limited herein; in an alternative embodiment, the preset time can be specified according to a percentage of tracking time, for example, 99%; and the preset value can be 0.5.

[0140] Through experimental measurement, the polarization control effects of the same polarization controller operating at different phase modulation speeds are compared, as shown in FIG. 1. Figure 5 FIG. 2 shows a complementary cumulative distribution of a main clock 8000 division, as shown in FIG. 3. Figure 6 FIG. 4 shows a complementary cumulative distribution of a main clock 1600 division, as shown in FIG. 5. Figure 7 FIG. 6 shows a complementary cumulative distribution of a main clock 800 division, and through comparison of the relative intensity error curves, if the maximum polarization tracking speed is determined by 99% of the time being less than 0.5, it can be obviously observed that the phase modulation speed affects the polarization tracking speed. For a 2-fold phase modulation speed, the tracking speed also reaches 2-fold. Therefore, for an algorithm with a certain number of iterations, increasing the phase modulation speed will significantly improve the tracking speed.

[0141] The embodiment of the present application determines the optimal phase modulation speed, and then a subsequent control algorithm controls the polarization controller to perform tracking experiments according to the optimal phase modulation speed. In the iteration process, because the gradient descent algorithm has the most suitable gradient direction, fixed step convergence can lead to slow convergence. In the prior art, there are many functions that can achieve step length modulation factors that change synchronously with feedback light intensity, that is, step length can be adjusted steplessly. However, in actual application, a complex adjustment process is required, and the corresponding algorithm is too sensitive to noise interference and has low robustness.

[0142] The embodiment of the present application provides a variable step length algorithm for optimizing the convergence speed of the gradient descent algorithm. The variable step length control model based on the variable step length algorithm is used to perform tracking experiments, the convergence speed of tracking experiments in each iteration is accelerated, and the control parameters of the variable step length control model that enable the fastest tracking speed are determined after iteration. Specifically, as shown in Figure 8 In step 20, the polarization controller is controlled to track the polarization light randomly disturbed by different perturbation speeds according to the optimal phase modulation speed. The phase shift amount of the phase shifter in the polarization controller is iteratively adjusted according to the feedback light intensity of the polarization controller and the step length modulation factor through the variable step length control model.

[0143] In step 201, in each iteration process, for each phase shifter in the polarization controller, the phase shift amount of the phase shifter is increased or decreased by a current step length based on the corresponding feedback light intensity, so as to adjust the phase shift amount of the phase shifter in the corresponding iteration direction.

[0144] In the first iteration process, the initial current step length is selected by a person skilled in the art according to a specific use scenario.

[0145] In step 202, the polarization controller updates the feedback light intensity according to the adjusted phase shift amount, compares the updated feedback light intensity with the updated feedback light intensity, and determines the iteration direction of adjusting the phase shift amount of the phase shifter next time according to the comparison result.

[0146] In step 203, the polarization controller obtains output light according to the adjusted phase shift amount, determines the step length modulation factor of the current iteration according to the output light, and updates the current step length for the next iteration according to the step length modulation factor of the current iteration.

[0147] The determination method of the step length modulation factor of the current iteration can be as follows:

[0148] The current state point of the output light on the Poincaré sphere is determined, the target point of the polarization state of the output light on the Poincaré sphere is determined, and the adjustment reference distance between the current state point and the target point is determined. When the adjustment reference distance is greater than the feedback light threshold, a first multiple value is determined as the step size modulation factor; when the adjustment reference distance is less than or equal to the feedback light threshold, a second multiple value is determined as the step size modulation factor; wherein, the first multiple value is greater than the second multiple value. The feedback light threshold, the first multiple value, and the second multiple value are selected by those skilled in the art according to the specific application scenario; the variable step size algorithm of this embodiment achieves step size modulation by setting the feedback light threshold, using a smaller step size when the feedback light intensity does not exceed the feedback light threshold, and using a larger step size (for example, the larger step size used is 3 times the smaller step size) when the feedback light intensity exceeds the feedback light threshold.

[0149] The step size modulation factor can adjust the step size of the phase shifter based on the feedback light intensity, i.e., the distance between the current state and the target point, thereby reducing the number of iterations and quickly converging to the required state of s1 = ±1. The variable step size algorithm of this invention can make full use of the gradient direction of a single measurement for large step size convergence, significantly reducing the number of iterations and improving the polarization tracking effect.

[0150] This embodiment performs speed simulations for two algorithms, comparing the tracking performance of the fixed-step-size algorithm and the variable-step-size algorithm by applying the same perturbation velocity. Figure 9 The image shows the swerve trajectory using a fixed step size algorithm, as shown below. Figure 10 The image shows the tracking effect using a fixed step size algorithm; as shown. Figure 11 The image shows the perturbation trajectory using the variable step size algorithm, as shown below. Figure 12 The image shows the tracking effect using the variable step size algorithm; as shown. Figures 9-12 As shown, compared to the long-term loss of lock with a fixed step size, the variable step size algorithm only has a few loss points. Obviously, the variable step size algorithm greatly improves the convergence ability of the polarization controller when searching for the fastest tracking speed through the gradient descent algorithm.

[0151] This invention improves the robustness of the program and the adaptability of software and hardware through the gradient descent algorithm, while reducing the complexity of the control algorithm. By introducing a step size modulation factor, the number of iterations of the gradient descent algorithm is reduced. In this embodiment, for a specific polarization controller, the matching between the phase modulation speed of the control algorithm and the actual response speed of the polarization controller is considered, significantly improving the tracking speed of the polarization controller and maximizing the thermal-optical phase modulation speed.

[0152] Example 2:

[0153] To implement the method in Example 1, such as Figure 13As shown, the embodiment of the present application also provides a device for improving polarization tracking speed, which comprises a laser, a polarization scrambler, a polarization controller and a control unit.

[0154] The laser is configured to generate an original light source.

[0155] The polarization scrambler is configured to randomly scramble the original light source at different polarization scrambling speeds to obtain corresponding polarized light.

[0156] The control unit is configured to control the polarization controller to track the polarized light randomly scrambled at different polarization scrambling speeds, to iteratively adjust the phase shift of the phase shifter in the polarization controller according to the feedback light intensity of the polarization controller at a specified step size until the feedback light intensity tends to zero, to determine the optimal phase modulation speed adapted by the polarization controller, and to control the polarization controller to track the polarized light randomly scrambled at different polarization scrambling speeds according to the optimal phase modulation speed. The control unit is also configured to iteratively adjust the phase shift of the phase shifter in the polarization controller according to the feedback light intensity of the polarization controller and a step size modulation factor through a variable step size control model until the feedback light intensity tends to zero to obtain the control parameters of the variable step size control model. In an optional embodiment, the control unit can comprise a control circuit including a digital-to-analog / analog-to-digital converter, a photodetector and a transimpedance amplifier, and an FPGA, and the control circuit is configured to perform signal processing.

[0157] The polarization controller is configured to track the polarized light randomly scrambled at different polarization scrambling speeds. The polarization controller can be an automatic polarization controller (APC).

[0158] As shown, the device for improving polarization tracking speed of the embodiment of the present application can further comprise an optical amplifier configured to amplify the polarized light with a random polarization state. An oscilloscope is configured to observe and record the optical signal converted by the photodetector at the output and feedback ports. The polarized light output from the optical amplifier (i.e., the optical signal shown in the middle) is input to the polarization controller, and the output with a specified polarization state is obtained from the polarization controller. A part of the directly output polarized light is transmitted to the oscilloscope through the PD to transmit the corresponding signal to the oscilloscope, and the remaining part of the polarized light is used as feedback light and transmitted to the control unit through the PD to transmit the corresponding signal to the control unit, and the control unit controls the related parameters of the polarization controller in the next iteration according to the feedback. Figure 13 Figure 13

[0159] Example 3: In an optional embodiment, as shown in

[0160] Figure 14 ​​Fig. 1 is a schematic diagram of an architecture of a control unit for improving polarization tracking speed according to an embodiment of the present application. The control unit for improving polarization tracking speed according to the embodiment includes one or more processors 21 and a memory 22. In the embodiment, the processor 21 is taken as an example. Figure 14

[0161] The processor 21 and the memory 22 can be connected through a bus or other means, Figure 14 In the embodiment, the connection through the bus is taken as an example.

[0162] The memory 22 is a non-volatile computer readable storage medium, which can be used to store non-volatile software programs and non-volatile computer executable programs, such as the method for improving polarization tracking speed according to the embodiment. The processor 21 executes the method for improving polarization tracking speed by running the non-volatile software programs and instructions stored in the memory 22.

[0163] The memory 22 can include a high-speed random access memory, and can also include a non-volatile memory, such as at least one magnetic disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 22 can optionally include a memory remotely arranged with respect to the processor 21, and these remote memories can be connected to the processor 21 through a network. Examples of the above-mentioned network include but are not limited to the Internet, an intranet, a local area network, a mobile communication network, and a combination thereof.

[0164] The program instructions / modules are stored in the memory 22, and when executed by the one or more processors 21, the method for improving polarization tracking speed in the above-mentioned embodiment is executed, for example, each step in the method for improving polarization tracking speed according to the embodiment of the present application is executed.

[0165] The embodiment of the present application also provides a non-volatile computer storage medium, which stores computer executable instructions. The computer executable instructions are executed by one or more processors, for example Figure 14 a processor 21, so that the above-mentioned one or more processors can execute the method for improving polarization tracking speed in the specific embodiment of the present application, for example, execute each step in the method for improving polarization tracking speed according to the embodiment of the present application; and can also realize Figure 14 the various modules, units; or execute the method for improving polarization tracking speed in the specific embodiment of the present application, for example, execute each step in the method for improving polarization tracking speed according to the embodiment of the present application; and can also realize Figure 14 the various modules, units.

[0166] ​It is worth mentioning that the information interaction, execution process and the like between the modules and units in the above apparatus and system are based on the same concept as the processing method embodiments of the present application, and the specific content can be referred to the description in the method embodiments of the present application, which will not be repeated here.

[0167] Those skilled in the art can understand that all or part of the steps in the various methods of the embodiments can be completed by relevant hardware instructed by a program, and the program can be stored in a computer readable storage medium, which can include read only memory (ROM), random access memory (RAM), magnetic disk or optical disk, etc.

[0168] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for improving polarization tracking speed, characterized by, The method comprises the following steps: controlling the polarization controller to track the polarization light randomly disturbed by different disturbance velocities; adjusting the phase shift of the phase shifter in the polarization controller according to the feedback light intensity of the polarization controller and a specified step size, until the feedback light intensity tends to zero; determining the optimal phase modulation speed adapted by the polarization controller; controlling the polarization controller to track the polarization light randomly disturbed by different disturbance velocities according to the optimal phase modulation speed; adjusting the phase shift of the phase shifter in the polarization controller according to the feedback light intensity of the polarization controller and a step size modulation factor through a variable step size control model, until the feedback light intensity tends to zero, obtaining the control parameters of the variable step size control model, so that the polarization controller uses the optimal phase modulation speed and the control parameters for tracking.

2. The method of boosting polarization tracking speed according to claim 1, wherein, The step of adjusting the phase shift of the phase shifter in the polarization controller according to the feedback light intensity of the polarization controller and a specified step size, until the feedback light intensity tends to zero comprises the following steps: for each phase shifter in the polarization controller, increasing or decreasing the phase shift of the phase shifter by a specified step size based on the corresponding feedback light intensity, so as to adjust the phase shift of the phase shifter in the corresponding iteration direction; the polarization controller updates the feedback light intensity according to the adjusted phase shift; comparing the updated feedback light intensity with the feedback light intensity before updating, and determining the iteration direction of adjusting the phase shift of the phase shifter next time according to the comparison result; iterating the above process until the feedback light intensity of the polarization controller tends to zero.

3. The method of boosting polarization tracking speed according to claim 2, wherein, The step of determining the optimal phase modulation speed adapted by the polarization controller comprises the following steps: recording the phase modulation speed of the phase shifter and the corresponding tracking speed of the polarization controller in each iteration process; comparing the tracking speeds of the polarization controller at different phase modulation speeds to determine the mapping relationship between the phase modulation speed and the tracking speed; based on the mapping relationship, the optimal phase modulation speed adapted by the polarization controller is obtained.

4. The method of boosting polarization tracking speed according to claim 3, wherein, The step of comparing the tracking speeds of the polarization controller at different phase modulation speeds to determine the mapping relationship between the phase modulation speed and the tracking speed comprises the following steps: The polarization controller tracks the polarization light randomly disturbed by different disturbance speeds at different phase modulation speeds; relative intensity differences of each iteration are determined, and the relative intensity differences at the same disturbance speed are taken as the same group of sample data; wherein, the expression of the relative intensity difference is: I FB is the feedback light intensity, I OUT is the output light intensity of the polarization controller; calculating the complementary cumulative distribution according to a plurality of sample data; constructing the relative intensity difference curve according to the plurality of sample data and the corresponding complementary cumulative distribution; comparing the relative intensity difference curves when tracking at different phase modulation speeds, and obtaining the mapping relationship when the relative intensity difference of the polarization controller within a preset time is less than a preset value.

5. The method of boosting polarization tracking speed according to claim 4, wherein, The step of calculating the complementary cumulative distribution according to a plurality of sample data comprises the following steps: obtaining the first sample quantity of each sample data; obtaining the second sample quantity of the relative intensity difference less than the intensity difference threshold in each sample data; determining the ratio of the second sample quantity to the first sample quantity as the cumulative distribution value F(RIE); obtaining the complementary cumulative distribution of the plurality of sample data according to all the complementary cumulative distribution values 1-F(RIE) corresponding to the plurality of sample data.

6. The method of boosting polarization tracking speed of claim 2, wherein, In the iteration process, it further comprises the following steps: adjusting the clock division multiple of controlling the polarization controller to track, so that the waiting response time of the polarization controller is the shortest, and the tracking speed of the polarization controller is improved; The waiting response time is from the time of adjusting the phase shift of the phase shifter in the current iteration to the time of the adjusted phase shifter responding to the adjustment.

7. The method of boosting polarization tracking speed of claim 1, wherein, The polarization controller is controlled to track the polarized light randomly disturbed at different disturbance speeds according to the optimal phase modulation speed. The phase shift of the phase shifter in the polarization controller is iteratively adjusted according to the feedback light intensity of the polarization controller and a step length modulation factor through a variable step length control model, including: In each iteration process, for each phase shifter in the polarization controller, the phase shift of the phase shifter is increased or decreased by a current step length based on the corresponding feedback light intensity, so as to adjust the phase shift of the phase shifter in a corresponding iteration direction; The polarization controller updates the feedback light intensity according to the adjusted phase shift, compares the updated feedback light intensity with the feedback light intensity before the update, and determines the iteration direction of the adjustment of the phase shift of the phase shifter in the next time according to the comparison result; The polarization controller obtains output light according to the adjusted phase shift, determines a step length modulation factor of the current iteration according to the output light, and updates a current step length for the next iteration according to the step length modulation factor of the current iteration.

8. The method of boosting polarization tracking speed according to claim 7, wherein, The step length modulation factor of the current iteration is determined according to the output light, including: A current state point of the output light on a Poincare sphere is determined, a target point of a polarization state of the output light on the Poincare sphere is determined, and an adjustment reference distance between the current state point and the target point is determined; When the adjustment reference distance is greater than a feedback light threshold, a first multiple value is determined as the step length modulation factor; when the adjustment reference distance is less than or equal to the feedback light threshold, a second multiple value is determined as the step length modulation factor; wherein the first multiple value is greater than the second multiple value.

9. The method of boosting polarization tracking speed according to any one of claims 1-8, wherein, The Jones matrix of the phase shifter is: wherein is the phase shift of the phase shifter, j is the imaginary part of a complex number; The Jones matrix of the coupler in the polarization controller is: The phase shifters and the couplers are alternately arranged and combined to form the polarization controller; when the polarization controller is a two-stage phase modulation structure, the Jones matrix of the polarization controller is: wherein E OUT represents the output light intensity of the polarization controller, E FB represents the feedback light intensity of the polarization controller, E x represents the light intensity of the incident light X-direction polarization, E y represents the light intensity of the incident light Y-direction polarization, represents the phase shift amount of the first stage phase shifter of the polarization controller, represents the phase shift amount of the second stage phase shifter of the polarization controller.

10. An apparatus for improving polarization tracking speed, characterized by, The system comprises a laser, a disturbance instrument, a polarization controller, and a control unit. The laser is configured to generate an original light source. The disturbance instrument is configured to randomly disturb the original light source at different disturbance speeds to obtain corresponding polarized light. The control unit is configured to control the polarization controller to track the polarized light randomly disturbed at different disturbance speeds, iteratively adjust the phase shift of the phase shifter in the polarization controller according to the feedback light intensity of the polarization controller and a specified step length until the feedback light intensity tends to zero, determine an optimal phase modulation speed to which the polarization controller is adapted, and control the polarization controller to track the polarized light randomly disturbed at different disturbance speeds according to the optimal phase modulation speed; the phase shift of the phase shifter in the polarization controller is iteratively adjusted according to the feedback light intensity of the polarization controller and a step length modulation factor through a variable step length control model until the feedback light intensity tends to zero, and a control parameter of the variable step length control model is obtained. The polarization controller is configured to track the polarized light randomly disturbed at different disturbance speeds.

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