A silicon-based liquid crystal optical cross system and control method

Abstract

The application provides a silicon-based liquid crystal optical cross system and a control method, and relates to the field of optical elements, which comprises a fiber array, a microlens array, a collimating lens, a polarization conversion module, a dispersion element, a focusing lens group and a liquid crystal spatial light modulator. The microlens array is used for coupling light signals and compressing the divergence angle, and a double-cemented collimating lens is used for forming a parallel light beam; the polarization conversion module is used for separating the light beam into P / S polarized light and unifying the polarization state; the dispersion element is used for separating the light beam according to the wavelength space, and the focusing lens group is used for forming an elliptical Gaussian light spot on the liquid crystal spatial light modulator; the liquid crystal spatial light modulator is used for dividing the long-axis direction of the light spot into multiple independent control regions, and the reflection phase of each region is dynamically modulated to realize single-wavelength multi-port output, power proportioning regulation and monitoring signal extraction. The control method comprises optical path processing, regionalized phase modulation and real-time monitoring feedback. The application can realize flexible routing, power balancing and lossless monitoring of wavelength channels.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical communication and optical signal processing, and in particular to an optical cross system based on silicon-based liquid crystal and a control method. BACKGROUND

[0002] With the rapid development of 5G communication, Internet of Things, cloud computing and other technologies, the demand for transmission capacity, flexibility and dynamic reconfigurability of optical communication networks continues to rise. The traditional fixed optical network architecture has been difficult to meet the dynamic scheduling demand of wavelength resources in multiple service scenarios, thus giving rise to the widespread application of reconfigurable optical add-drop multiplexer (ROADM) technology. As the core device of the ROADM system, the wavelength selective switch (WSS) dynamically controls the wavelength routing of optical signals, realizes the flexible allocation of optical layer resources and the intelligent reconstruction of network topology, and becomes one of the key technologies for building flexible optical networks.

[0003] The current mainstream WSS technology is mainly based on micro-electro-mechanical system (MEMS), liquid crystal (LC) or silicon-based optical solutions. Among them, the MEMS technology has obvious shortcomings in wavelength channel number scalability (usually no more than 20 channels) and long-term stability due to the physical limitations of its mechanical structure. The LC solution improves the tunability to some extent, but its response speed is relatively slow (usually >10 ms), and the insertion loss is high (≥5 dB), which makes it difficult to meet the demand of high-speed optical networks. Although silicon-based optical devices have made breakthroughs in integration, they still face problems such as complex manufacturing process and high cost, which limit their large-scale commercialization. In addition, with the evolution of optical networks to flexible grid (Flexi-Grid) and ultra-dense wavelength division multiplexing (DWDM), traditional WSSs gradually show deficiencies in wavelength resolution, channel spacing adjustment accuracy and multi-dimensional control capability.

[0004] In recent years, the LCoS-based WSS technology has gradually become a research hotspot in the field of optical communication due to its high resolution, low power consumption, fast response and high integration, etc. LCoS combines liquid crystal layer with silicon-based reflective micro-display technology, and precisely controls the phase and polarization of light wavefront through high-density pixel array (with sub-micron level precision), thereby realizing the functions of wavelength selection, power balancing and multi-port switching in a single device. Compared with traditional solutions, LCoS-WSS has significant software-defined characteristics, and can be compatible with new optical network architectures by upgrading the control algorithm, becoming a key enabling technology to support the evolution of optical transmission networks towards flexibility and intelligence.

[0005] However, the existing LCOS-WSS scheme still faces problems such as spectral power imbalance, insufficient multi-channel crosstalk suppression, and lack of real-time signal monitoring, which need to be further improved through device structure optimization and system-level innovation. SUMMARY

[0006] In view of this, the embodiments of the present application provide a silicon-based liquid crystal optical cross system and a control method to eliminate or improve one or more defects in the prior art, solve the problems of uneven spectral power, insufficient multi-channel crosstalk suppression and lack of real-time signal monitoring in the prior art.

[0007] In one aspect, the present application provides a silicon-based liquid crystal optical cross system, which comprises:

[0008] An optical fiber array comprising an input port, a plurality of output ports and at least one monitoring port for input and output of optical signals;

[0009] A microlens array connected to the optical fiber array for coupling the optical signals and reducing the divergence angle to obtain a divergent light beam;

[0010] A collimating lens for collimating the divergent light beam to form a parallel light beam;

[0011] A polarization conversion module for adjusting the polarization state of the parallel light beam;

[0012] A dispersion element for spatially separating the light beam obtained by adjusting the polarization conversion module according to wavelength to obtain separated light beams of different wavelengths;

[0013] A focusing lens group for focusing the separated light beams of different wavelengths to different spatial positions of a liquid crystal spatial light modulator;

[0014] A liquid crystal spatial light modulator for receiving each wavelength light beam output by the focusing lens group, dynamically modulating the reflection phase of each wavelength light beam received based on a programmable pixel array, directing the reflection of each wavelength light beam to a selected output port, and adjusting the proportion of optical power reflected to each port;

[0015] A monitoring port for receiving part of the reflected optical signal from the liquid crystal spatial light modulator for signal detection.

[0016] In some embodiments of the present application, the system further comprises:

[0017] A first half-wave plate arranged in the incident light path of the liquid crystal spatial light modulator for calibrating the polarization direction of the reflected light to match the modulation requirements.

[0018] In some embodiments of the present application, the collimating lens adopts a double-cemented lens system based on a telescope structure, comprising a first convex lens and a second convex lens arranged in sequence along the light path:

[0019] The first convex lens has a short focal length for compressing the beam waist radius of the divergent light beam;

[0020] The second convex lens has a long focal length, and is configured to expand the light beam processed by the first convex lens.

[0021] In some embodiments of the present application, the system further comprises:

[0022] The first convex lens compresses the waist radius of the divergent light beam, and the compressed light beam parameter transformation satisfies the following formula:

[0023] ;

[0024] The second convex lens expands the light beam processed by the first convex lens, and the maximum expansion multiple of the waist radius of the output light beam satisfies the following formula:

[0025] ;

[0026] The parameter configuration of the double-cemented lens system satisfies the following formula:

[0027] ;

[0028] wherein, represents the distance between the waist of the divergent light beam and the first convex lens; represents the distance between the waist of the compressed light beam and the first convex lens; represents the focal length of the first convex lens; represents the Rayleigh length of the divergent light beam; represents the waist radius of the light beam processed by the first convex lens; represents the waist radius of the output light beam of the second convex lens; represents the focal length of the second convex lens; represents the distance between the waist of the output light beam of the second convex lens and the second convex lens; represents the distance between the first convex lens and the second convex lens.

[0029] In some embodiments of the present application, the polarization conversion module further comprises:

[0030] A polarization beam splitting prism is configured to separate the parallel light beam into first polarized light and second polarized light according to the polarization direction, wherein the first polarized light is directly transmitted, and the second polarized light is reflected to the first light path;

[0031] A second half-wave plate is arranged in the first light path, and is configured to rotate the polarization direction of the second polarized light by 90° to be consistent with the first polarized light;

[0032] a right-angle prism configured to receive the second polarized light rotated by the second half-wave plate and reflect the second polarized light to a second optical path parallel to the first polarized light, so that the two beams of light are incident to the dispersive element with the same polarization state.

[0033] In some embodiments of the present application, the dispersive element is a diffraction grating configured to separate the incident light of the same polarization state into a plurality of monochromatic lights of different wavelengths, each monochromatic light being emitted at a different diffraction angle to form a spatially distributed wavelength channel.

[0034] In some embodiments of the present application, the grating period of the diffraction grating satisfies the following grating diffraction equation:

[0035] ;

[0036] wherein, denotes the grating period of the diffraction grating; denotes the angle between the incident light and the grating normal; denotes the angle between the diffracted light and the grating normal; denotes the wavelength of the incident light; denotes the diffraction order.

[0037] In some embodiments of the present application, the liquid crystal spatial light modulator dynamically modulates the reflection phase of each wavelength light beam received based on a programmable pixel array, comprising:

[0038] The relationship between the deflection angle of the liquid crystal molecules of each pixel and the driving voltage satisfies the following formula:

[0039] ;

[0040] wherein, denotes the deflection angle of the liquid crystal molecules; denotes the driving voltage; denotes the threshold voltage; denotes the saturation voltage;

[0041] The relationship between the phase change amount of the reflected light and the deflection angle of the liquid crystal molecules satisfies the following formula:

[0042] ;

[0043] wherein, denotes the phase change amount of the reflected light; denotes the thickness of the liquid crystal layer; denotes the wavelength of the incident light; denotes the corresponding relationship between the deflection angle of the liquid crystal molecules and the extraordinary refractive index; denotes the ordinary refractive index;

[0044] The light spot formed by the focusing lens group on the liquid crystal spatial light modulator is an elliptical Gaussian distribution, as shown in the formula:

[0045] ;

[0046] wherein, and respectively represent the beam waist radius of the focusing direction and .

[0047] In some embodiments of the present application, the liquid crystal spatial light modulator divides the long axis direction of the light spot into a plurality of independent control regions, and by adjusting the phase change of each independent control region, the light beams of the same wavelength are reflected to selected different output ports, while the light power ratio reflected to each output port is controlled.

[0048] On the other hand, the present application provides a silicon-based liquid crystal optical cross control method, which comprises the following steps:

[0049] Receiving optical signals through a fiber array and distributing the optical signals to a plurality of output ports and at least one monitoring port;

[0050] Coupling the optical signals using a microlens array and reducing the divergence angle to generate divergent light beams;

[0051] Collimating the divergent light beams using a collimating lens to generate parallel light beams;

[0052] Adjusting the polarization state of the parallel light beams through a polarization conversion module to form a polarization-unified light beam;

[0053] Spatially separating the polarization-unified light beam into a plurality of wavelength channel light beams using a dispersive element;

[0054] Focusing each wavelength channel light beam to different spatial positions of a liquid crystal spatial light modulator through a focusing lens group to form spatially distributed light spots;

[0055] Dividing each light spot corresponding to a wavelength into a plurality of independent control regions along the long axis direction; independently setting a driving voltage for each independent control region to generate a corresponding reflected light phase change; by adjusting the phase change of each independent control region, the wavelength light beams are directionally reflected to selected output ports, and the light power ratio reflected to each output port is dynamically adjusted;

[0056] Selecting the reflected light of a specific independent control region and introducing it into the monitoring port for performance analysis, and dynamically optimizing the control parameters of the liquid crystal spatial light modulator according to the analysis results.

[0057] The application provides a silicon-based liquid crystal-based optical cross system and a control method.

[0058] Additional advantages, objects, and features of the application will be set forth in part by the description that follows, and will become apparent to those skilled in the art upon examination of the following or can be learned by practice of the application. The objects and other advantages of the application can be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

[0059] To those skilled in the art, it will be understood that the objects and advantages of the application realized by the application are not limited to the above specific description, and the above and other objects realized by the application will be more clearly understood according to the following detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0060] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description, serve to explain the principles of the application.

[0061] Figure 1 It is a schematic diagram of the three-dimensional structure of the overall optical path of the silicon-based liquid crystal-based optical cross system in an embodiment of the application.

[0062] Figure 2 It is a schematic diagram of the plane of the optical path under different viewing angles of the silicon-based liquid crystal-based optical cross system in an embodiment of the application.

[0063] Figure 3 It is a schematic diagram of the working principle of the collimating lens in an embodiment of the application.

[0064] Figure 4 It is a schematic diagram of the structure and working principle of the polarization conversion module in an embodiment of the application.

[0065] REFERENCE NUMERALS

[0066] (1) fiber array; (2) microlens array; (3) collimating lens;

[0067] (4) polarization conversion module; (5) dispersion element; (6) focusing lens group;

[0068] (7) first half-wave plate; (8) liquid crystal spatial light modulator; (9) polarization beam splitter prism;

[0069] (10) second half-wave plate; (11) right-angle prism. DETAILED DESCRIPTION

[0070] In order to make the objectives, technical solutions, and advantages of the present application clearer, further detailed descriptions will be given to the present application in combination with embodiments and drawings. Herein, the illustrative embodiments of the present application and their descriptions are used to explain the present application, but not as limitations to the present application.

[0071] It should be noted that, in order to avoid the present application being obscured by unnecessary details, only the structures and / or processing steps closely related to the solutions according to the present application are shown in the drawings, and other details not closely related to the present application are omitted.

[0072] It should be emphasized that the term “comprising / comprising” as used herein refers to the presence of a feature, element, step, or component, but does not exclude the presence or addition of one or more other features, elements, steps, or components.

[0073] It should be noted that, if not otherwise specified, the term “connection” as used herein can not only refer to direct connection, but also indirect connection with an intermediate.

[0074] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. In the drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

[0075] It should be emphasized that the step labels mentioned hereinafter are not limitations to the order of the steps, but should be understood as that the steps can be performed in the order mentioned in the embodiments, or in an order different from the embodiments, or several steps can be performed simultaneously.

[0076] In order to solve the problems of uneven spectral power, insufficient multi-channel crosstalk suppression, and lack of real-time signal monitoring in the prior art, the present application provides a silicon-based liquid crystal-based optical cross system, as shown in Figure 1 The system comprises:

[0077] The fiber array (1) comprises an input port, a plurality of output ports, and at least one monitoring port, and is used for input and output of optical signals.

[0078] The microlens array (2) is connected to the fiber array (1) to couple optical signals and reduce the divergence angle to obtain a diverging beam.

[0079] The collimating lens (3) is used to collimate the diverging beam obtained by the microlens array (2) to form a parallel beam.

[0080] The polarization conversion module (4) is used to adjust the polarization state of the parallel beam.

[0081] The dispersive element (5) is used to spatially separate the beam obtained by the polarization conversion module (4) according to the wavelength, so as to obtain separated beams of different wavelengths.

[0082] The focusing lens group (6) is used to focus the separated light beams of different wavelengths onto different spatial positions of the liquid crystal spatial light modulator (8).

[0083] The liquid crystal spatial light modulator (8) is used to receive the wavelength beams output by the focusing lens group (6), dynamically modulate the reflection phase of the received wavelength beams based on the programmable pixel array, directionally reflect each wavelength beam to the selected output port, and adjust the ratio of light power reflected to each port.

[0084] The monitoring port is used to receive partially reflected light signals from the liquid crystal spatial light modulator (8) for signal detection.

[0085] In some embodiments, the system further includes a first half-wave plate (7) disposed in the incident light path of the liquid crystal spatial light modulator (8) for further calibrating the polarization direction of the reflected light to match the modulation requirements.

[0086] like Figure 2 The diagram shown is a dual-view schematic of the optical cross-connection system of the present invention, wherein the upper view is a schematic of the optical path under the YZ plane, and the lower view is a schematic of the optical path under the XZ plane.

[0087] Fiber optic arrays are typically 1×N type, meaning one input port and N output ports. Preferably, in this invention, one of the output ports is used as a monitoring port.

[0088] The microlens array, connected to the fiber optic array, can be understood as a set of miniature magnifying glasses, with each microlens precisely aligned with a single fiber. The curvature of the lens surface refocuses the diverging beam output from the fiber optic array, achieving optical signal coupling. Simultaneously, the specific curvature of the lens allows incident light from different angles to exit in a more parallel direction, thus performing initial collimation of the beam and reducing the divergence angle.

[0089] The collimating lens precisely collimates the divergent beam that has been initially collimated by the microlens array, correcting the divergent beam into a parallel beam.

[0090] In some embodiments, as shown in Figure 3 The collimating lens adopts a doublet lens system based on a telescope structure, including a first convex lens and a second convex lens arranged in sequence along the light path. The first convex lens has a short focal length and is used to compress the beam waist radius of the divergent light beam; the second convex lens has a long focal length and is used to expand the light beam processed by the first convex lens.

[0091] The first convex lens of the doublet lens system first compresses the beam waist radius of the divergent light beam, and the parameter transformation of the compressed light beam satisfies the following formula (1):

[0092] ; (1)

[0093] wherein, represents the distance between the beam waist of the divergent light beam and the first convex lens; represents the distance between the beam waist of the compressed light beam and the first convex lens; represents the focal length of the first convex lens; represents the Rayleigh length of the divergent light beam.

[0094] The second convex lens expands the light beam processed by the first convex lens, wherein the maximum expansion multiple of the beam waist radius of the output light beam satisfies the following formula (2):

[0095] ; (2)

[0096] wherein, represents the beam waist radius of the light beam processed by the first convex lens; represents the beam waist radius of the output light beam of the second convex lens; represents the focal length of the second convex lens.

[0097] The parameter configuration of the doublet lens system satisfies the following formula (3) at the same time:

[0098] ; (3)

[0099] wherein, represents the distance between the beam waist of the output light beam of the second convex lens and the second convex lens; represents the distance between the first convex lens and the second convex lens.

[0100] After the processing of the above doublet lens system, the maximum output light beam waist radius can be achieved, and the beam waist position of the output light beam is located on the focal plane of the second convex lens, so that the output light beam is most parallel at this position, i.e. the divergence angle is the smallest, and the spot shape is the most round and regular.

[0101] In some embodiments of the present application, as shown in Figure 4As shown, the polarization conversion module further includes a polarization beam splitting prism (9), a second half-wave plate (10), and a right-angle prism (11). Specifically,

[0102] The polarization beam splitting prism is made of a birefringent crystal such as yttrium vanadate (YVO4), and is used to separate a parallel light beam into a first polarized light and a second polarized light according to the polarization direction, wherein the first polarized light (P-polarized light, corresponding to the TE mode in the waveguide) is directly transmitted, and the second polarized light (S-polarized light, corresponding to the TM mode in the waveguide) is reflected to the first light path. Among them, the P-polarized light refers to the vibration direction of the electric vector being parallel to the incident plane; the S-polarized light refers to the vibration direction of the electric vector being perpendicular to the incident plane, that is, perpendicular to the plane formed by the optical path and the interface normal.

[0103] The second half-wave plate is arranged in the first light path, and is used to rotate the polarization direction of the second polarized light by 90° to be consistent with the first polarized light.

[0104] The right-angle prism is used to receive the second polarized light after being rotated by the second half-wave plate and reflect it to the second light path parallel to the first polarized light, so that the two beams of light are incident to the dispersion element with the same polarization state.

[0105] In some embodiments, the dispersion element usually adopts a diffraction grating. Specifically, the diffraction grating separates the incident light of the same polarization state obtained after the polarization conversion module into a plurality of monochromatic lights of different wavelengths according to the wavelength, and each monochromatic light exits with a different diffraction angle, forming a spatially distributed wavelength channel.

[0106] In some embodiments, the grating period of the diffraction grating satisfies the following grating diffraction equation, as formula (4):

[0107] ; (4)

[0108] wherein, denotes the grating period of the diffraction grating; denotes the included angle between the incident light and the grating normal; denotes the included angle between the diffracted light and the grating normal; denotes the wavelength of the incident light; denotes the diffraction order.

[0109] In some embodiments, the focusing lens group adopts a double-cemented lens system, which is used to focus the separated light beams of different wavelengths to different spatial positions of the liquid crystal spatial light modulator.

[0110] Liquid crystal spatial light modulator (LCoS) is a programmable optical modulator based on CMOS technology, whose core structure is composed of a silicon substrate integrated with driving circuit, a liquid crystal cell and a high reflectivity electrode layer. When an external electrical signal is loaded to the CMOS circuit, each pixel can independently apply an accurate voltage, and the light phase modulation is realized through the orientation change of the voltage-sensitive liquid crystal molecules. Specifically, when the applied voltage exceeds the threshold voltage, the deflection angle of the liquid crystal molecules follows a nonlinear response curve, and finally the reflected light produces a phase delay related to the deflection angle, which is determined by the thickness of the liquid crystal layer, the extraordinary refractive index and the wavelength of the incident light.

[0111] In some embodiments, the relationship between the deflection angle of the liquid crystal molecules of each pixel and the driving voltage satisfies the following formula (5):

[0112] ; (5)

[0113] wherein, represents the deflection angle of the liquid crystal molecules; represents the driving voltage; represents the threshold voltage; represents the saturation voltage.

[0114] In some embodiments, the relationship between the phase change of the reflected light and the deflection angle of the liquid crystal molecules satisfies the following formula (6):

[0115] ; (6)

[0116] wherein, represents the phase change of the reflected light; represents the thickness of the liquid crystal layer; represents the wavelength of the incident light; represents the corresponding relationship between the deflection angle of the liquid crystal molecules and the extraordinary refractive index; represents the ordinary refractive index.

[0117] In formula 6, the corresponding relationship between the deflection angle of the liquid crystal molecules and the extraordinary refractive index satisfies the following formula (7):

[0118] ; (7)

[0119] wherein, and respectively represent the ordinary refractive index and the extraordinary refractive index under the condition of no voltage.

[0120] Since the incident light is an ideal Gaussian beam, when passing through the focusing lens group, the beam will be transformed asymmetrically in two dimensions, because the focusing lens group only has focusing power in a single direction (such as the x direction), and has no optical power in the orthogonal direction (such as the y direction). In the focusing direction (x axis), the focusing lens group's refractive effect will reduce the beam waist radius to 1 / M times the original value (M is the magnification), while the divergence angle in this direction increases by M times; in the non-focusing direction (y axis), the beam parameters maintain the original Gaussian characteristics before the incident. This selective transformation results in an elliptical Gaussian intensity distribution, which can be mathematically expressed as shown in equation (8):

[0121] ; (8)

[0122] wherein, and represent the beam waist radii in the focusing direction and , respectively.

[0123] This controllable asymmetric beam shaping characteristic is the physical basis for realizing wavelength channel spatial separation and LCoS regionalized modulation in the optical cross system: the expansion of the long axis (y direction) of the ellipse matches the multi-wavelength arrangement requirement of the dispersion dimension, and the short axis (x direction) ensures the accurate positioning of each wavelength spot in the port dimension.

[0124] Since the spot intensity is Gaussian distributed, there is a natural gradient difference in the light power carried by each region (the center region has the maximum light intensity, and the edge region decreases), therefore, the liquid crystal spatial light modulator divides the long axis direction of the spot into multiple independent control regions, by applying different voltage signals to each independent control region, the phase change amount of the corresponding liquid crystal cell is accurately controlled, so that the same wavelength beam can be decomposed into multiple independently controlled sub-beams, for example, the center high-power region mainly carries the service signal, which can be directed to the output port; the low-power edge region is allocated to the monitoring port (such as extracting 1% to 5% of the power), which can analyze key parameters of the signal in real time, such as optical signal-to-noise ratio (OSNR), bit error rate (BER), wavelength shift, modulation error, etc., without affecting the transmission of the main signal, realizing lossless monitoring of the service.

[0125] The application also provides a silicon-based liquid crystal-based optical cross control method, which is realized by a silicon-based liquid crystal-based optical cross system, and includes the following steps S101-S108:

[0126] Step S101: receiving an optical signal through a fiber array, and distributing the optical signal to multiple output ports and at least one monitoring port.

[0127] Step S102: coupling the light signal by using a microlens array, reducing the divergence angle, and generating a divergent light beam.

[0128] Step S103: collimating the divergent light beam by using a collimating lens, and generating a parallel light beam.

[0129] Step S104: adjusting the polarization state of the parallel light beam by using a polarization conversion module, and forming a polarization-unified light beam.

[0130] Step S105: spatially separating the polarization-unified light beam according to wavelengths by using a dispersion element, and generating a plurality of wavelength-channel light beams.

[0131] Step S106: focusing each wavelength-channel light beam to different spatial positions of a liquid crystal spatial light modulator by using a focusing lens group, and forming spatially distributed light spots.

[0132] Step S107: dividing each light spot corresponding to a wavelength into a plurality of independently controlled regions along a long axis direction; independently setting a driving voltage for each independently controlled region, generating a corresponding reflected light phase change amount; and directing each wavelength light beam to a selected output port by adjusting the phase change amount of each independently controlled region, and dynamically adjusting the light power ratio reflected to each output port.

[0133] Step S108: selecting reflected light of a specific independently controlled region, and introducing the reflected light into a monitoring port for performance analysis; and dynamically optimizing the control parameters of the liquid crystal spatial light modulator according to the analysis results.

[0134] Corresponding to the above method, the application further provides an electronic device, which comprises a computer device including a processor and a memory, the memory storing computer instructions, and the processor being configured to execute the computer instructions stored in the memory, so that the electronic device implements the steps of the above method.

[0135] The application further provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of the above method.

[0136] It should be noted that the application is not limited to the specific configurations and processes described above and shown in the drawings. For the sake of brevity, detailed descriptions of well-known methods are omitted herein. In the above embodiments, a number of specific steps are described and shown as examples. However, the method process of the application is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order of the steps, after understanding the spirit of the application.

[0137] Features described and / or illustrated with respect to one implementation can be used in the same manner or in a similar manner in one or more other implementations and / or in combination with or in place of features of other implementations.

[0138] The above descriptions are only the preferred embodiments of the present application, not intended to limit the present application. The embodiments of the present application can be variously changed and / or modified by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall fall within the scope of the present application.

Claims

1. A silicon-based liquid crystal optical crossover system, characterized in that, The system includes: An optical fiber array, including an input port, multiple output ports and at least one monitoring port, is used for the input and output of optical signals; A microlens array, connected to the fiber optic array, is used to couple the optical signal and reduce the divergence angle to obtain a diverging beam; A collimating lens is used to collimate the diverging beam to form a parallel beam. A polarization conversion module is used to adjust the polarization state of the parallel beam; A dispersive element is used to spatially separate the beam obtained by the polarization conversion module according to wavelength, so as to obtain separated beams of different wavelengths; A focusing lens group is used to focus the separated light beams of different wavelengths onto different spatial positions of the liquid crystal spatial light modulator, and to form an elliptical Gaussian spot on the liquid crystal spatial light modulator. The liquid crystal spatial light modulator is used to divide the elliptical Gaussian spot corresponding to each wavelength into multiple independent control regions along the long axis direction, and dynamically modulate the reflection phase of each independent control region based on a programmable pixel array, so as to directionally reflect each wavelength beam to the selected output port and adjust the ratio of light power reflected to each port. The monitoring port is used to receive partially reflected light signals from the liquid crystal spatial light modulator, perform signal detection, and dynamically optimize the control parameters of the liquid crystal spatial light modulator.

2. The optical cross-connect system based on silicon-based liquid crystal according to claim 1, characterized in that, The system also includes: The first half-wave plate is disposed in the incident light path of the liquid crystal spatial light modulator and is used to calibrate the polarization direction of the reflected light to match the modulation requirements.

3. The optical cross-connect system based on silicon-based liquid crystal according to claim 1, characterized in that, The collimating lens employs a double cemented lens system based on a telescope structure, comprising a first convex lens and a second convex lens arranged sequentially along the optical path: The first convex lens has a short focal length to compress the waist radius of the diverging beam; The second convex lens has a long focal length and is used to expand the beam after it has been processed by the first convex lens.

4. The optical cross-connect system based on silicon-based liquid crystal according to claim 3, characterized in that, Also includes: The first convex lens compresses the beam waist radius of the diverging beam, and the transformed beam parameters after compression satisfy the following formula: ； The second convex lens expands the beam processed by the first convex lens, and the maximum expansion factor of the output beam's beam waist radius satisfies the following formula: ； The parameter configuration of the cemented doublet lens system simultaneously satisfies the following formula: ； in, This indicates the distance between the waist of the diverging beam and the first convex lens; This indicates the distance between the compressed beam waist and the first convex lens; This indicates the focal length of the first convex lens; This represents the Rayleigh length of the diverging beam; This represents the beam waist radius of the light beam after it has been processed by the first convex lens; This represents the beam waist radius of the output beam from the second convex lens; This indicates the focal length of the second convex lens; This indicates the distance between the beam waist of the output beam from the second convex lens and the second convex lens; This indicates the distance between the first convex lens and the second convex lens.

5. The optical cross-connect system based on silicon-based liquid crystal according to claim 1, characterized in that, The polarization conversion module also includes: A polarizing beam splitter is used to separate the parallel beam into a first polarized light and a second polarized light according to the polarization direction, wherein the first polarized light is directly transmitted and the second polarized light is reflected to the first optical path. The second half-wave plate is disposed in the first optical path and is used to rotate the polarization direction of the second polarized light by 90° to match that of the first polarized light. A right-angle prism is used to receive the second polarized light after it has been rotated by the second half-wave plate and reflect it to a second optical path parallel to the first polarized light, so that the two beams of light are incident on the dispersive element with the same polarization state.

6. The optical cross-connect system based on silicon-based liquid crystal according to claim 1, characterized in that, The dispersive element is a diffraction grating, which separates incident light of the same polarization state into multiple monochromatic lights of different wavelengths according to wavelength. Each monochromatic light exits at a different diffraction angle, forming a spatially distributed wavelength channel.

7. The optical cross-connect system based on silicon-based liquid crystal according to claim 6, characterized in that, The grating period of the diffraction grating satisfies the following grating diffraction equation: ； in, This indicates the grating period of the diffraction grating; This indicates the angle between the incident light and the grating normal; This indicates the angle between the diffracted light and the normal to the grating. Indicates the wavelength of the incident light; Indicates the diffraction order.

8. The optical cross-connect system based on silicon-based liquid crystal according to claim 1, characterized in that, The liquid crystal spatial light modulator dynamically modulates the reflection phase of each wavelength beam received based on a programmable pixel array, including: The relationship between the deflection angle of the liquid crystal molecules in each pixel and the driving voltage satisfies the following formula: ； in, This indicates the deflection angle of the liquid crystal molecules; This represents the driving voltage; Indicates the threshold voltage; Indicates saturation voltage; The relationship between the phase change of the reflected light and the deflection angle of the liquid crystal molecules satisfies the following formula: ； in, This indicates the amount of phase change in the reflected light; Indicates the thickness of the liquid crystal layer; Indicates the wavelength of the incident light; This indicates the relationship between the deflection angle of the liquid crystal molecules and the anomalous refractive index; Indicates the ordinary refractive index; The light spot formed by the focusing lens group on the liquid crystal spatial light modulator has an elliptical Gaussian distribution, as shown in the formula: ； in, and These represent the focusing directions. and The waist radius.

9. The optical cross-connect system based on silicon-based liquid crystal according to claim 8, characterized in that, The liquid crystal spatial light modulator divides the long axis of the light spot into multiple independent control regions. By adjusting the phase change of each independent control region, the same wavelength light beam is reflected to different selected output ports, while controlling the ratio of light power reflected to each output port.

10. A method for controlling optical crossover based on silicon-based liquid crystal, characterized in that, The method includes the following steps: Optical signals are received via an optical fiber array and distributed to multiple output ports and at least one monitoring port. The optical signal is coupled using a microlens array, and the divergence angle is reduced to generate a diverging beam. The diverging beam is collimated using a collimating lens to generate a parallel beam. The polarization state of the parallel beam is adjusted by a polarization conversion module to form a beam with uniform polarization. The uniformly polarized beam is spatially separated by wavelength using a dispersive element to generate multiple wavelength channel beams. The beams of each wavelength channel are focused onto different spatial positions of the liquid crystal spatial light modulator by a focusing lens group, forming spatially distributed light spots; The light spot corresponding to each wavelength is divided into multiple independent control regions along the long axis; the driving voltage is set independently for each independent control region to generate the corresponding phase change of the reflected light; by adjusting the phase change of each independent control region, the light beam of each wavelength is directionally reflected to the selected output port, and the ratio of light power reflected to each output port is dynamically adjusted. The reflected light from a specific independent control area is selected and imported into the monitoring port for performance analysis. Based on the analysis results, the control parameters of the liquid crystal spatial light modulator are dynamically optimized.

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