A wave plate cascade scrambling device and a scrambling method based on outer rotation and inner rotation forms

Abstract

The application discloses a wave plate cascade disturbance device and method based on outer rotation and inner rotation forms, and the device comprises an optical transmitter, a disturbance module and a calculation module. The method comprises the following steps: acquiring polarized light with a fixed polarization state; determining a transmission matrix of an outer rotation model and a transmission matrix of an inner rotation model given a disturbance speed and a white noise distribution; performing decomposition conversion processing on the transmission matrix of the outer rotation model and the transmission matrix of the inner rotation model to obtain three-level electrical signals; and performing polarization state adjustment processing on the polarized light with the fixed polarization state according to the three-level electrical signals to obtain adjusted polarized light. The application can independently control the disturbance speed and the polarization probability distribution, improve the controllability of the disturbance model, and realize high-speed polarization disturbance with strong adjustability. The application can be widely applied to the technical field of polarized light disturbance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polarized light perturbation, and in particular to a wave plate cascade perturbation device and method based on external rotation and internal rotation forms. BACKGROUND

[0002] Different polarization light application scenarios have different requirements for perturbation devices. In the working scenario of suppressing polarization-related damage, the perturbation device needs to depolarize the polarized light to reduce the influence of the polarization dependence of the device on the system; for the test scenario of communication algorithm, the perturbation device needs to generate an output polarization state with high adjustability and uniform distribution on the Poincare sphere. The current perturbation device is mainly used to generate an output polarization state with high-speed perturbation and low polarization degree, and the perturbation performance is improved by improving the hardware structure. In addition, all-optical perturbation technology has also attracted widespread attention. This structure based on de-coherent interaction achieves the perturbation effect, has low insertion loss, and has the advantage of simple structure. However, the related perturbation research mainly focuses on developing advanced polarization control structures to achieve an output polarization state with low polarization degree and high change rate. In recent years, research has gradually shifted to controlling the statistical distribution characteristics of the output polarization state after perturbation. However, the driving signal form used by the mainstream perturbation device based on the rotating wave plate structure design is often complex, it is difficult to obtain the transfer function of the model, control the polarization statistical characteristics of the polarization state, and the model lacks sufficient theoretical guidance for control, and the controllability is poor.

[0003] To sum up, the technical problems in the related art need to be improved. SUMMARY

[0004] The main purpose of the embodiments of the present application is to provide a wave plate cascade perturbation device and method based on external rotation and internal rotation forms, which can independently control the perturbation speed and the polarization probability distribution, improve the controllability of the perturbation model, and realize high-speed polarization perturbation with strong adjustability.

[0005] To achieve the above-mentioned purpose, one aspect of the embodiments of the present application provides a wave plate cascade perturbation device based on external rotation and internal rotation forms, which comprises a light transmitter, a perturbation module and a calculation module, the perturbation module is a wave plate cascade perturbation device based on an external rotation model and an internal rotation model, the output end of the light transmitter is connected with the first input end of the perturbation module, and the output end of the calculation module is connected with the second input end of the perturbation module, wherein:

[0006] The light transmitter is used to emit polarized light with a fixed polarization state;

[0007] The calculation module is used to perform decomposition and conversion processing according to the transfer matrix of the external rotation model and the transfer matrix of the internal rotation model to obtain a three-level electrical signal;

[0008] The perturbation module is configured to perform polarization state adjustment on the polarized light according to the three-level electrical signal, to obtain adjusted polarized light.

[0009] In some embodiments, the computing module includes a field programmable gate array, a first digital-to-analog converter, a second digital-to-analog converter, and a third digital-to-analog converter, and the output of the field programmable gate array is connected to the input of the first digital-to-analog converter, the input of the second digital-to-analog converter, and the input of the third digital-to-analog converter, respectively, wherein:

[0010] The field programmable gate array is configured to decompose the transmission matrix of the outer spin model and the transmission matrix of the inner spin model to obtain three-level basic rotation matrices, and determine three phase delays and control voltage signals corresponding to the three phase delays according to the three-level basic rotation matrices.

[0011] The first digital-to-analog converter, the second digital-to-analog converter, and the third digital-to-analog converter are configured to convert the control voltage signals to obtain a first electrical signal, a second electrical signal, and a third electrical signal, respectively.

[0012] In some embodiments, the perturbation module includes a polarization beam splitter, a three-level MZI structure-based perturbation device, and a polarization beam combiner, the output of the polarization beam splitter is connected to the input of the three-level MZI structure-based perturbation device, and the output of the three-level MZI structure-based perturbation device is connected to the input of the polarization beam combiner, wherein:

[0013] The polarization beam splitter is configured to split the polarized light to obtain split polarized light.

[0014] The three-level MZI structure-based perturbation device is configured to rotate the polarization state of the split polarized light around a Poincare sphere axis to obtain adjusted split polarized light.

[0015] The polarization beam combiner is configured to synthesize the adjusted split polarized light to obtain the adjusted polarized light.

[0016] In some embodiments, the three-level MZI structure-based perturbation device includes a first voltage control structure, a second voltage control structure, and a third voltage control structure, and the first voltage control structure, the second voltage control structure, and the third voltage control structure are connected in sequence, wherein:

[0017] The first voltage control structure is configured to control the rotation of the polarization state of the split polarized light around a Poincare sphere S3 axis.

[0018] The second-stage voltage control structure is configured to control the polarization state of the split polarized light to rotate around a Poincare sphere S1 axis;

[0019] The third-stage voltage control structure is configured to control the polarization state of the split polarized light to rotate around a Poincare sphere S3 axis.

[0020] In some embodiments, the first-stage voltage control structure includes a first multimode interference coupler, a first phase shifter, and a second multimode interference coupler, the second-stage voltage control structure includes a second phase shifter, and the third-stage voltage control structure includes a third multimode interference coupler, a third phase shifter, and a fourth multimode interference coupler, wherein:

[0021] The first multimode interference coupler and the third multimode interference coupler are configured to perform power distribution on the polarization state of the split polarized light;

[0022] The first phase shifter, the second phase shifter, and the third phase shifter are configured to obtain the first electrical signal, the second electrical signal, and the third electrical signal, respectively, and perform phase difference adjustment on the polarization state of the split polarized light;

[0023] The third multimode interference coupler and the fourth multimode interference coupler are configured to perform power distribution on the polarization state of the split polarized light.

[0024] To achieve the above object, another aspect of the embodiments of the present application proposes a polarization scrambling method of a wave plate cascade polarization scrambling device based on external rotation and internal rotation, the method comprising:

[0025] Obtaining polarized light with a fixed polarization state;

[0026] Given a scrambling speed and a white noise distribution, determining a transmission matrix of the external rotation model and a transmission matrix of the internal rotation model;

[0027] Performing decomposition and conversion processing on the transmission matrix of the external rotation model and the transmission matrix of the internal rotation model to obtain three-stage electrical signals, the three-stage electrical signals including a first electrical signal, a second electrical signal, and a third electrical signal;

[0028] According to the three-stage electrical signals, performing polarization state adjustment on the polarized light with the fixed polarization state to obtain adjusted polarized light.

[0029] In some embodiments, the transmission matrix of the external rotation model and the transmission matrix of the internal rotation model have the following expressions, respectively:

[0030] M k1 = M(η,φ k )M k-1 = R2(φ k)R3(η)M k-1

[0031] M k2 = M k-1 M(η,φ k ) = M k-1 R3(η)R2(φ k )

[0032] In the above formula, M k1 represents the transmission matrix of the outer spin model, M k2 represents the transmission matrix of the inner spin model, φ k represents the Gaussian white noise at time k, M(·) represents the evolution matrix, M k-1 represents the transmission matrix at the previous time, η represents the rotation angle, R2 represents the basic rotation matrix for rotating the polarization state around the S2 axis of the Poincare sphere, and R3 represents the basic rotation matrix for rotating the polarization state around the S3 axis of the Poincare sphere.

[0033] In some embodiments, the transmission matrix of the outer spin model and the transmission matrix of the inner spin model are decomposed and converted to obtain a three-level electrical signal, including:

[0034] The transmission matrix of the outer spin model and the transmission matrix of the inner spin model are decomposed to obtain a three-level basic rotation matrix;

[0035] Three phase delays and control voltage signals corresponding to the three phase delays are determined according to the three-level basic rotation matrix;

[0036] The control voltage signals are converted to obtain the three-level electrical signals.

[0037] In some embodiments, the polarization state of the polarized light with a fixed polarization state is adjusted according to the three-level electrical signals to obtain adjusted polarized light, including:

[0038] The polarized light with a fixed polarization state is split to obtain split polarized light;

[0039] The polarization state of the split polarized light is rotated around the Poincare sphere axis according to the three-level electrical signals to obtain adjusted split polarized light;

[0040] The adjusted split polarized light is synthesized to obtain the adjusted polarized light.

[0041] In some embodiments, the polarization state of the split polarized light is rotated around the Poincare sphere axis according to the three-level electrical signals to obtain adjusted split polarized light, including:

[0042] According to the first electrical signal, a polarization state of the split polarized light is rotated around a Poincare sphere S3 axis to obtain first rotated split polarized light;

[0043] According to the second electrical signal, a polarization state of the first rotated split polarized light is rotated around a Poincare sphere S1 axis to obtain second rotated split polarized light;

[0044] According to the third electrical signal, a polarization state of the second rotated split polarized light is rotated around a Poincare sphere S3 axis to obtain the adjusted split polarized light.

[0045] The embodiments of the present application at least have the following beneficial effects: the present application provides a wave plate cascade scrambling device and a scrambling method based on the forms of external rotation and internal rotation, the scheme constructs a scrambling module based on the wave plate cascade scrambler of the external rotation model and the internal rotation model, and then introduces a calculation module, controls the scrambling speed and the polarization probability distribution through two independent parameters of the external rotation model and the internal rotation model, improves the controllability of the scrambling model, and realizes high-speed polarization disturbance with strong adjustability. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is a structure schematic diagram of a wave plate cascade scrambling device based on the forms of external rotation and internal rotation provided by the embodiments of the present application;

[0047] Figure 2 is a step schematic diagram of a scrambling method of a wave plate cascade scrambling device based on the forms of external rotation and internal rotation provided by the embodiments of the present application.

[0048] Reference signs: 100, optical transmitter; 200, scrambling module; 210, polarization beam splitter; 220, scrambling device based on three-level MZI structure; 221, first voltage control structure; 222, second voltage control structure; 223, third voltage control structure; 230, polarization beam combiner; 300, calculation module; 310, field programmable gate array; 320, first digital-to-analog converter; 330, second digital-to-analog converter; 340, third digital-to-analog converter. DETAILED DESCRIPTION

[0049] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, and are not intended to limit the present application. When the following description refers to the accompanying drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with embodiments of the present application. They are only examples of systems and methods consistent with some aspects of the embodiments of the present application as detailed in the appended claims.

[0050] It can be understood that the terms "first", "second", and the like used in the present application can be used herein to describe various concepts, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of the present application, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information. Depending on the context, the word "if" as used herein can be interpreted as "when" or "when" or "in response to determining".

[0051] The terms "at least one", "multiple", "each", "any" and the like used in the present application include one, two or more than two, multiple includes two or more than two, each refers to each of the corresponding multiple, and any refers to any one of the multiple.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as understood by those skilled in the art to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0053] Referring to Figure 1 , Figure 1 A structure diagram of a wave plate cascade scrambling device based on an outer rotation and an inner rotation form is provided for the embodiments of the present application, referring to Figure 1 The wave plate cascade scrambling device includes a light transmitter 100, a scrambling module 200 and a calculation module 300. The scrambling module is a wave plate cascade scrambler based on an outer rotation model and an inner rotation model. The output end of the light transmitter is connected to the first input end of the scrambling module, and the output end of the calculation module is connected to the second input end of the scrambling module. Wherein:

[0054] The light transmitter is used to emit polarized light with a fixed polarization state;

[0055] Specifically, the light transmitter is used to output a beam of polarized light with a fixed polarization state.

[0056] The computing module is configured to perform decomposition conversion processing on the transmission matrix of the outer spin model and the transmission matrix of the inner spin model to obtain three-level electrical signals.

[0057] In the embodiment of the present application, the computing module includes a field programmable gate array 310, a first digital-to-analog converter 320, a second digital-to-analog converter 330, and a third digital-to-analog converter 340. The output of the field programmable gate array is connected to the input of the first digital-to-analog converter, the input of the second digital-to-analog converter, and the input of the third digital-to-analog converter, respectively. The field programmable gate array is configured to perform decomposition processing on the transmission matrix of the outer spin model and the transmission matrix of the inner spin model to obtain three-level basic rotation matrices, and determine three phase delays and control voltage signals corresponding to the three phase delays according to the three-level basic rotation matrices. The first digital-to-analog converter, the second digital-to-analog converter, and the third digital-to-analog converter are configured to perform conversion processing on the control voltage signals to obtain first electrical signals, second electrical signals, and third electrical signals.

[0058] Specifically, the computing module includes an FPGA (field programmable gate array), three digital-to-analog converters (DACs) electrically connected to the FPGA, namely a first digital-to-analog converter DA, a second digital-to-analog converter DA, and a third digital-to-analog converter DA. The FPGA decomposes the transmission matrices of the outer spin model and the inner spin model at the current time into three basic rotation matrices and outputs control voltage signals. The digital-to-analog converters are electrically connected to the three-level phase shifters and convert the control voltage signals output by the FPGA into electrical signals and input them into the three-level phase shifters of the perturbation module.

[0059] The perturbation module is configured to perform polarization state adjustment processing on the polarized light according to the three-level electrical signals to obtain adjusted polarized light.

[0060] In the embodiment of the present application, the perturbation module includes a polarization beam splitter 210, a perturbation device 220 based on a three-level MZI structure, and a polarization beam combiner 230. The output of the polarization beam splitter is connected to the input of the perturbation device based on a three-level MZI structure, and the output of the perturbation device based on a three-level MZI structure is connected to the input of the polarization beam combiner. The polarization beam splitter is configured to perform beam splitting processing on the polarized light to obtain split polarized light. The perturbation device based on a three-level MZI structure is configured to perform rotation processing on the polarization state of the split polarized light around the Poincare sphere axis to obtain adjusted split polarized light. The polarization beam combiner is configured to perform synthesis processing on the adjusted split polarized light to obtain adjusted polarized light.

[0061] Specifically, the perturber based on the three-stage MZI structure includes a first-stage voltage control structure 221, a second-stage voltage control structure 222, and a third-stage voltage control structure 223, which are sequentially connected, wherein the first-stage voltage control structure is configured to control the polarization state of the split polarized light to rotate around the S3 axis of the Poincare sphere; the second-stage voltage control structure is configured to control the polarization state of the split polarized light to rotate around the S1 axis of the Poincare sphere; and the third-stage voltage control structure is configured to control the polarization state of the split polarized light to rotate around the S3 axis of the Poincare sphere.

[0062] Specifically, the first-stage voltage control structure includes a first multi-mode interference coupler (MMI), a first phase shifter (PS1), and a second multi-mode interference coupler (MMI), the second-stage voltage control structure includes a second phase shifter (PS2), and the third-stage voltage control structure includes a third multi-mode interference coupler (MMI), a third phase shifter (PS3), and a fourth multi-mode interference coupler (MMI), wherein the first multi-mode interference coupler and the third multi-mode interference coupler are configured to perform power distribution on the polarization state of the split polarized light; the first phase shifter, the second phase shifter, and the third phase shifter are configured to obtain first, second, and third electrical signals, respectively, and perform phase difference adjustment on the polarization state of the split polarized light; and the third multi-mode interference coupler and the fourth multi-mode interference coupler are configured to perform power distribution on the polarization state of the split polarized light.

[0063] It should be noted that the perturbation module includes a polarization beam splitter (PBS), a perturber, and a polarization beam combiner (PBC), the three-stage voltage control structure of the perturber is composed of MZI structures, each stage of the MZI structure corresponds to a basic rotation matrix, wherein the first stage and the third stage are composed of two multi-mode interference couplers (MMIs) and a phase shifter (PS) located in the middle, and the function realized is to make the polarization state rotate around the S3 axis on the Poincare sphere, and the second stage is composed of a phase shifter, and the function realized is to make the polarization state rotate around the S1 axis on the Poincare sphere. That is, the first-stage MZI structure of the perturber is composed of two multi-mode interference couplers and a phase shifter located in the middle, which can realize the effect of rotating the polarization state around the S3 axis on the Poincare sphere, the second-stage MZI structure is composed of a phase shifter, which can realize the effect of rotating the polarization state around the S1 axis on the Poincare sphere, and the third stage has the same structure as the first stage and realizes the same polarization state rotation effect.

[0064] Please refer to Figure 2 The application also provides a perturbation method of the wave plate cascade perturbation device based on the external rotation and internal rotation forms, which can realize the above-mentioned wave plate cascade perturbation device based on the external rotation and internal rotation forms, and the method comprises the following steps:

[0065] S100, obtaining polarized light with a fixed polarization state;

[0066] It should be noted that in some embodiments, the light transmitter emits a beam of polarized light with a fixed polarization state into the polarization beam splitter of the scrambling module.

[0067] S200, given the scrambling speed and white noise distribution, determine the transmission matrix of the outer spin model and the transmission matrix of the inner spin model;

[0068] It should be noted that the outer spin and inner spin models use two adjustable cascaded wave plates to model the evolution of the output polarization state at adjacent time, and the two adjustable parameters are scrambling speed v and Gaussian white noise distribution φ respectively. The evolution matrix of the outer spin model is in the form of multiplication of two 3x3 basic rotation matrices R2(φ k )R3(η), which is multiplied on the left of the transmission matrix of the previous time to describe the evolution relationship of the polarization state at adjacent time. The evolution matrix of the inner spin model is in the form of multiplication of two 3x3 basic rotation matrices R3(η)R2(φ k ), which is multiplied on the right of the transmission matrix of the previous time to model the change of the scrambling model at adjacent time. The transmission matrix of the outer spin model is the result of continuous left multiplication of the evolution matrices of all times, and the transmission matrix of the inner spin model is the result of continuous right multiplication of the evolution matrices of all times, which can be represented as:

[0069] M k1 =M(η,φ k )M k-1 =R2(φ k )R3(η)M k-1

[0070] M k2 =M k-1 M(η,φ k )=M k-1 R3(η)R2(φ k )

[0071] where the rotation angle η=υT, υ is the adjustable scrambling speed, which can be used to control the scrambling speed, T=1 / f s is the system sampling time, f s is the system sampling rate; φ k is the Gaussian white noise at time k, which can be used to control the statistical probability distribution of the polarization disturbance.

[0072] where the evolution matrix of the outer spin model is M 外 (·)=R2(φ k )R3(η), and the evolution matrix of the inner spin model is M 内 (·)=R3(η)R2(φ k ).

[0073] The basic rotation matrixes R1 (δ), R2 (δ), R3 (δ) of rotating δ around the S1, S2, S3 axes of the Poincare sphere are respectively:

[0074]

[0075] The transmission matrix M of the outer and inner spin model k The transmission matrix M k1 The transmission matrix M k2 ) can be decomposed into the form of three basic rotation matrixes R3 (θ3) R1 (θ2) R3 (θ1) multiplied, and the phase delays θ1, θ2, θ3 can be obtained according to the matrix decomposition method, and are respectively:

[0076] θ1=tan -1 (m 31 ,m 32 )

[0077]

[0078] θ3=tan -1 (m 13 ,-m 23 )

[0079] Where m ij are elements in the transmission matrix M k , i is a row, and j is a column.

[0080] S300, the transmission matrix of the outer spin model and the transmission matrix of the inner spin model are decomposed and converted, to obtain a three-level electrical signal, and the three-level electrical signal includes a first electrical signal, a second electrical signal and a third electrical signal.

[0081] It should be noted that in some embodiments, step S300 can include: S310, the transmission matrix of the outer spin model and the transmission matrix of the inner spin model are decomposed and converted, to obtain a three-level basic rotation matrix; S320, three phase delays and control voltage signals corresponding to the three phase delays are determined according to the three-level basic rotation matrix; S330, the control voltage signals are converted to obtain a three-level electrical signal.

[0082] In some specific embodiments, given a perturbation velocity v and a white noise distribution φ, the calculation module decomposes the three-dimensional transmission matrix M k of the outer and inner spin model at time k into a three-level basic rotation matrix R3 (θ3) R1 (θ2) R3 (θ1), and obtains the control voltage signals V1, V2, V3 of the three-level phase shifters of the perturber in the perturbation module according to the phase delays θ1, θ2, θ3 of the basic rotation matrixes.

[0083] S400, performing polarization state adjustment processing on the polarized light with the fixed polarization state according to the three-level electrical signal, to obtain adjusted polarized light;

[0084] It should be noted that in some embodiments, step S400 can include: S410, performing beam splitting processing on the polarized light with the fixed polarization state, to obtain split polarized light; S420, performing rotation processing on the polarization state of the split polarized light around the Poincare sphere axis according to the three-level electrical signal, to obtain adjusted split polarized light; and S430, performing synthesis processing on the adjusted split polarized light, to obtain the adjusted polarized light.

[0085] It should be noted that in some embodiments, step S420 can include: S421, performing rotation processing on the polarization state of the split polarized light around the Poincare sphere S3 axis according to the first electrical signal, to obtain first rotated split polarized light; S422, performing rotation processing on the polarization state of the first rotated split polarized light around the Poincare sphere S1 axis according to the second electrical signal, to obtain second rotated split polarized light; and S423, performing rotation processing on the polarization state of the second rotated split polarized light around the Poincare sphere S3 axis according to the third electrical signal, to obtain the adjusted split polarized light.

[0086] In some specific embodiments, the input signal light is divided into mutually orthogonal X and Y channel signals, the scrambler of the scrambling module receives the X and Y channel signals, and adjusts the polarization state according to the control voltage signal, and the polarization combiner combines the X and Y channel signals to obtain the output signal light, so that the output polarization state is uniformly distributed on the Poincare sphere.

[0087] That is, the optical transmitter outputs a signal light with a fixed polarization state, which is divided into mutually orthogonal X and Y channel signals after passing through the beam splitter of the scrambling module, and the two signals enter the scrambler. For a given scrambling speed v and white noise distribution φ, the calculation module decomposes the transmission matrix M k1 = M(η, φ k )M k-1 or the transmission matrix M k2 = M k-1 M(η, φ k ) of the right-handed model into three basic rotation matrices R3(θ3)R1(θ2)R3(θ1) corresponding to the three-level MZI structure of the scrambler, and the three phase delays are:

[0088] θ1 = tan -1 (m 31 ,m 32 )

[0089]

[0090] θ3=tan -1 (m 13 ,-m 23 )

[0091] where m ij are elements in the transmission matrix M k , i is a row, and j is a column.

[0092] The FPGA in the calculation module decomposes the transmission matrix into three basic rotation matrices to obtain corresponding phase delays, outputs control voltages required by the three-phase shifter according to the linear correspondence between the control voltage signal of the phase shifter and the phase delay, and the three digital-to-analog converters electrically connected to the FPGA convert the three control voltage signals into electrical signals and input them into the three-phase shifter of the perturbation shifter, so that the perturbation shifter driven by the control voltage realizes random disturbance to the input polarization state. The two X and Y signal lights pass through the three-MZI structure and then pass through the polarization beam combiner to be combined into an output signal light that is randomly disturbed and uniformly distributed on the Poincare sphere.

[0093] In summary, the embodiment of the application proposes a perturbation system capable of realizing the outer and inner spin models to realize random disturbance of the optical polarization state, which comprises a light transmitter, a perturbation module and a calculation module connected in sequence, and the perturbation module is composed of a polarization beam splitter, a perturbation shifter based on a three-MZI structure and a polarization beam combiner. The process of realizing the outer and inner spin models by using the perturbation system specifically comprises: the light transmitter outputs a polarized light with a fixed polarization state, the signal light enters the perturbation module and is first divided into X and Y components that are orthogonal to each other by the polarization beam splitter. The FPGA in the calculation module decomposes the transmission matrix at a certain moment into three basic rotation matrices R3(θ3)R1(θ2)R3(θ1) to obtain the phase delays θ1, θ2 and θ3 corresponding to the phase shifters in the three-MZI structure of the perturbation shifter, and the control voltage signals of the three-phase shifter are obtained according to the condition that the phase delay of the phase shifter is linearly related to the control voltage signal. The three digital-to-analog converters connected to the FPGA convert the control voltage signals V1, V2 and V3 output by the FPGA into electrical signals and input them into the three-phase shifter. The two X and Y components that are orthogonal to each other enter the perturbation shifter driven by the control voltage output by the calculation module, realize the disturbance effect of the transmission matrix based on the outer and inner spin models, and realize high-speed random adjustment of the input polarization state with strong adjustability. Finally, the polarization beam combiner combines the two X and Y components into an output polarization light that is randomly disturbed, and realizes the effect of uniformly distributing the output polarization state on the Poincare sphere.

[0094] The embodiment of the application calculates the transmission matrix corresponding to the polarization state disturbance process through the inner rotation and outer rotation model, decomposes the transmission matrix into three basic rotation matrices by the FPGA in the calculation module, obtains the phase delay of the three basic rotation matrices, calculates the control voltage signal by the linear mapping relationship, converts the voltage signal into an electric signal by the digital-to-analog converter and inputs the electric signal into the phase shifter, adjusts the polarization state by the three-stage phase shifter according to the control voltage, adjusts the disturbance speed and the statistical probability distribution of the polarization state by setting two parameters in the model, and realizes the high disturbance speed and the regulation and control of the statistical probability distribution of the polarization state.

[0095] It can be understood that the contents in the method embodiments are applicable to the system embodiments, the system embodiments specifically realize the functions same as the method embodiments, and achieve the beneficial effects same as the method embodiments.

[0096] The preferred embodiments of the application are described above with reference to the drawings, and the scope of the application is not limited by this. Any modification, equivalent replacement and improvement made by those skilled in the art without departing from the scope and essence of the application should be within the scope of the application.

Claims

1. A wave-plate based cascaded depolarization device in the form of an outer and inner rotator, characterized in that, The wave plate cascade scrambling device comprises a light transmitter, a scrambling module and a calculation module, the scrambling module is a wave plate cascade scrambler based on an outer spin model and an inner spin model, an output end of the light transmitter is connected with a first input end of the scrambling module, and an output end of the calculation module is connected with a second input end of the scrambling module, wherein: The light transmitter is used for transmitting polarized light with a fixed polarization state; The calculation module is used for performing decomposition conversion processing on a transmission matrix of the outer spin model and a transmission matrix of the inner spin model determined according to a given scrambling speed and white noise distribution, to obtain a three-level electrical signal; The scrambling module is used for performing polarization state adjustment processing on the polarized light according to the three-level electrical signal, to obtain adjusted polarized light.

2. The apparatus of claim 1, wherein, The calculation module comprises a field programmable gate array, a first digital-to-analog converter, a second digital-to-analog converter and a third digital-to-analog converter, and output ends of the field programmable gate array are connected with input ends of the first digital-to-analog converter, the second digital-to-analog converter and the third digital-to-analog converter respectively, wherein: The field programmable gate array is used for performing decomposition processing on the transmission matrix of the outer spin model and the transmission matrix of the inner spin model, to obtain three-level basic rotation matrices, and determining three phase delays and control voltage signals corresponding to the three phase delays according to the three-level basic rotation matrices; The first digital-to-analog converter, the second digital-to-analog converter and the third digital-to-analog converter are used for performing conversion processing on the control voltage signals respectively, to obtain a first electrical signal, a second electrical signal and a third electrical signal.

3. The apparatus of claim 1, wherein, The scrambling module comprises a polarization beam splitter, a scrambler based on a three-level optical interference effect optical device structure and a polarization beam combiner, an output end of the polarization beam splitter is connected with an input end of the scrambler based on the three-level optical interference effect optical device structure, and an output end of the scrambler based on the three-level optical interference effect optical device structure is connected with an input end of the polarization beam combiner, wherein: The polarization beam splitter is used for performing beam splitting processing on the polarized light, to obtain split polarized light; The scrambler based on the three-level optical interference effect optical device structure is used for performing rotation processing on a polarization state of the split polarized light around a Poincare sphere axis, to obtain adjusted split polarized light; The polarization beam combiner is used for performing synthesis processing on the adjusted split polarized light, to obtain the adjusted polarized light.

4. The apparatus of claim 3, wherein, The scrambler based on the three-level optical interference effect optical device structure comprises a first voltage control structure, a second voltage control structure and a third voltage control structure, and the first voltage control structure, the second voltage control structure and the third voltage control structure are connected in sequence, wherein: The first voltage control structure is used for controlling the polarization state of the split polarized light to perform rotation processing around a Poincare sphere S3 axis, to obtain first rotated split polarized light; The second voltage control structure is used for controlling the polarization state of the first rotated split polarized light to perform rotation processing around a Poincare sphere S1 axis, to obtain second rotated split polarized light; The third voltage control structure is used for controlling the polarization state of the second rotated split polarized light to perform rotation processing around a Poincare sphere S2 axis, to obtain the adjusted split polarized light. The third voltage control structure is used for controlling the polarization state of the second rotated split polarized light to rotate around a Poincare sphere S3 axis.

5. The apparatus of claim 4, wherein, The first voltage control structure comprises a first multimode interference coupler, a first phase shifter and a second multimode interference coupler, the second voltage control structure comprises a second phase shifter, and the third voltage control structure comprises a third multimode interference coupler, a third phase shifter and a fourth multimode interference coupler, wherein: The first multimode interference coupler and the second multimode interference coupler are used for power distribution of the polarization state of the split polarized light. The first phase shifter is used for obtaining the first voltage signal and adjusting the phase difference of the polarization state of the split polarized light, the second phase shifter is used for obtaining the second voltage signal and adjusting the phase difference of the polarization state of the first rotated split polarized light, and the third phase shifter is used for obtaining the third voltage signal and adjusting the phase difference of the polarization state of the second rotated split polarized light. The third multimode interference coupler and the fourth multimode interference coupler are used for power distribution of the polarization state of the second rotated split polarized light.

6. A method of applying to the wave plate cascade of the form of the outer rotation and the inner rotation according to any one of claims 1 to 5, characterized by, The method comprises the following steps: obtaining polarized light with a fixed polarization state; determining a transmission matrix of the outer rotation model and a transmission matrix of the inner rotation model given a depolarization speed and a white noise distribution; decomposing and converting the transmission matrix of the outer rotation model and the transmission matrix of the inner rotation model to obtain three-level electrical signals, wherein the three-level electrical signals comprise a first electrical signal, a second electrical signal and a third electrical signal; adjusting the polarization state of the polarized light with the fixed polarization state according to the three-level electrical signals to obtain adjusted polarized light.

7. The method of claim 6, wherein, The expressions of the transmission matrix of the outer rotation model and the transmission matrix of the inner rotation model are as follows: in the above formula, denotes the transmission matrix of the outer spin model, denotes the transmission matrix of the inner spin model, denotes denotes the Gaussian white noise at the time instant, denotes the evolution matrix, denotes the transmission matrix of the previous time instant, denotes the rotation angle, denotes the basic rotation matrix that rotates the polarization state around the S2 axis of the Poincare sphere, denotes the basic rotation matrix that rotates the polarization state around the S3 axis of the Poincare sphere.

8. The method of claim 6, wherein, the decomposition and conversion of the transmission matrix of the outer rotation model and the transmission matrix of the inner rotation model to obtain three-level electrical signals comprises: decomposing the transmission matrix of the outer rotation model and the transmission matrix of the inner rotation model to obtain three-level basic rotation matrices; determining three phase delays and control voltage signals corresponding to the three phase delays according to the three-level basic rotation matrices; converting the control voltage signals to obtain the three-level electrical signals.

9. The method of claim 6, wherein, the adjustment of the polarization state of the polarized light with the fixed polarization state according to the three-level electrical signals to obtain adjusted polarized light comprises: splitting the polarized light with the fixed polarization state to obtain split polarized light; rotating the polarization state of the split polarized light around a Poincare sphere axis according to the three-level electrical signals to obtain adjusted split polarized light; synthesizing the adjusted split polarized light to obtain the adjusted polarized light.

10. The method of claim 9, wherein, the rotation of the polarization state of the split polarized light around a Poincare sphere axis according to the three-level electrical signals to obtain adjusted split polarized light comprises: According to the first electric signal, a polarization state of the split polarized light is rotated around a S3 axis of a Poincare sphere to obtain first rotated split polarized light; According to the second electric signal, a polarization state of the first rotated split polarized light is rotated around a S1 axis of the Poincare sphere to obtain second rotated split polarized light; According to the third electric signal, a polarization state of the second rotated split polarized light is rotated around the S3 axis of the Poincare sphere to obtain the adjusted split polarized light.

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