Integratable wide spectrum dense channel WSS based on liquid crystal spatial light modulator

Abstract

The invention provides an integratable wide spectrum dense channel WSS based on a liquid crystal spatial light modulator, and the method comprises the steps: taking an axial symmetry AWG array as an input port / output port of the WSS, carrying out the dispersion of an input WDM signal, and carrying out the wave combination of an output optical signal; the polarization control module is used for converting the WDM signal into two beams of linearly polarized light in a single polarization state; the grating is used for dispersing linearly polarized light in the WDM signal along the x direction; the lens group is used for realizing polarization multiplexing in an x-z plane, converting offset of different angles into off-axis displacement to realize angle-space displacement conversion, and controlling the spot size through a 1: 1 4f system in a y-z plane; the spatial light modulator is used for carrying out pure phase wavefront modulation on optical signals, so that light with different wavelengths deflects at different angles in the x direction and returns along the same path in the y direction, and the problem that it is difficult for a WSS of a liquid crystal spatial light modulator to simultaneously achieve a wide working frequency spectrum covering a communication waveband and ultra-dense channel intervals lower than 50 GHz is solved.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to an integrable wide spectrum dense channel (WSS) based on a liquid crystal spatial light modulator. Background Art

[0002] Nowadays, the digital transformation of various industries and the growing number of mobile smart devices have placed high demands on communication capacity. Wavelength Division Multiplexing (WDM), as a mature technology, supports the simultaneous transmission of multiple wavelength channels and has become one of the main means of expanding the capacity of optical communication networks. However, with the increase in the number of channels in optical transmission networks, channel management has become an important issue. Reconfigurable Optical Add / Drop Multiplexer (ROADM) technology can be remotely operated through software to control the upload or download of any number of wavelength combinations in optical network nodes, playing a role in flexibly allocating different wavelengths. Compared with fixed switching methods, it reduces the risk of communication congestion and greatly improves communication efficiency. Wavelength Selective Switch (WSS), as an all-optical switching component in the ROADM architecture, can switch any wavelength channel in the WDM signal of the input port to any output port, playing a vital role in a large number of information interaction scenarios now and in the future. Currently, WSS switching technologies primarily utilize liquid crystal spatial light modulators (SLMs) or micro-electro-mechanical systems (MEMS). Liquid crystal spatial light modulators (SLMs) control the voltage across each pixel electrode to deflect liquid crystal molecules, thereby modulating the phase of spatial light and generating deflection. Their advantages include small size, light weight, simple structure, flexible pixel area allocation, support for integration, and flexible networking.

[0003] Increasing the number of channels has become a strategy for addressing the current shortage of spectrum resources. This increase in channels improves information transmission efficiency and reduces the probability of network congestion. Combined with the flexible network supported by liquid crystal spatial light modulators, this can further increase transmission capacity. Currently, the main approaches to achieving more channels are band expansion and reducing channel spacing.

[0004] The minimum channel spacing and spectral range that can be achieved by optical switching in current WSSs based on liquid crystal spatial light modulators (LCSSMs) primarily depend on the selected dispersion method. Currently, the dispersion units in wavelength selective switches mostly use diffraction gratings for dispersion, as the grating's operating spectrum fully covers the communications band. The grating's dispersion capability is related to its line density. Limited by the grating's manufacturing process and materials, the line density of gratings capable of supporting near-infrared dispersion is mostly less than 1800 lines / mm, limiting the grating's spectroscopic capability. The use of multiple gratings for multiple dispersions places extremely high demands on the uniformity of grating manufacturing and the precision of assembly and commissioning. It's difficult to achieve an ideal spot shape after the beam passes through the grating multiple times, and low insertion loss and crosstalk cannot be guaranteed. Therefore, achieving dispersion in dense channels below 50 GHz using gratings is extremely difficult. Arrayed waveguide gratings (AWGs) easily achieve wavelength separation in ultra-dense channels by leveraging the principle of multi-beam interference. Their transmission spectrum channels vary periodically within the free-space spectral range (FSR). However, achieving ultra-dense wavelength division multiplexing while simultaneously balancing multi-channel output is difficult. This is because increasing the number of channels places extremely high demands on the design structure, waveguide materials, and manufacturing processes, and the device footprint increases dramatically, hindering integration. In short, due to the limitations of the dispersion unit, WSSs based on liquid crystal spatial light modulators struggle to achieve both a wide operating spectrum and ultra-dense channels.

[0005] Therefore, there is an urgent need to propose an integrated wide-spectrum dense channel WSS based on liquid crystal spatial light modulator to solve the problem that the WSS of liquid crystal spatial light modulator is limited by the current dispersion unit technology and is difficult to simultaneously achieve a wide operating spectrum covering the communication band and an ultra-dense channel spacing below 50 GHz. Summary of the Invention

[0006] In order to overcome the problems existing in the related art, the present disclosure provides an integrated wide-spectrum dense channel WSS based on a liquid crystal spatial light modulator to solve the technical problem that the WSS of the liquid crystal spatial light modulator in the related art is limited by the current dispersion unit technology and it is difficult to simultaneously achieve a wide operating spectrum covering the communication band and an ultra-dense channel spacing below 50GHz.

[0007] One or more embodiments of this specification provide an integrable wide spectrum dense channel WSS based on a liquid crystal spatial light modulator, including an axisymmetric AWG array, a polarization control module, a grating, a lens group, and a spatial light modulator;

[0008] The axisymmetric AWG array is used as the input port / output port of the WSS to disperse the input WDM signal and combine the output optical signal;

[0009] The polarization control module is used to convert the WDM signal into two beams of linearly polarized light with a single polarization state;

[0010] The grating is used to disperse the linearly polarized light in the WDM signal along the x-direction;

[0011] The lens assembly is used to achieve polarization multiplexing using a 4f system in the xz plane, convert offsets of different angles into off-axis displacements using a 2f system to achieve angle-spatial displacement conversion, and control the spot size in the yz plane using a 1:1 4f system;

[0012] The spatial light modulator is used to perform pure phase wavefront modulation on the optical signal, so that light of different wavelengths is deflected at different angles in the x direction and returns along the original path in the y direction.

[0013] Preferably, the axisymmetric AWG array is composed of two groups of AWG arrays arranged in an axisymmetric manner, each group of AWG arrays includes an input AWG and several output AWGs, the input AWG is located in the middle of the array, and the output AWGs are arranged in parallel and at equal intervals on both sides.

[0014] Preferably, the input port / output port of the axisymmetric AWG array is in the form of an optical fiber port for light transmission;

[0015] The ports at the same position of different AWGs are arranged in sequence along the x-direction, and the ports on one side of the AWG output planar waveguide are arranged in sequence along the y-direction.

[0016] Preferably, the dispersing of the input WDM signal specifically comprises the following steps:

[0017] The input WDM signal is dispersed by the AWG array and decomposed into m narrow-channel-spaced WDM signals arranged along the y direction at the m output ports of the AWG array. Each output port of the AWG array contains n wavelength channels with a pairwise spacing of FSR spectrum width.

[0018] Preferably, the polarization control module is composed of a Wollaston prism and a half-wave plate, and is specifically configured as follows:

[0019] The WDM signal is split into two linearly polarized beams with orthogonal polarization states through a Wollaston prism;

[0020] One of the linearly polarized lights is converted into a linearly polarized light having the same polarization state as the other linearly polarized light by passing through a half-wave plate.

[0021] Preferably, it further comprises a fiber collimating lens array, wherein each collimating lens in the fiber collimating lens array corresponds to the outgoing light / incident light of an optical fiber port at the input port / output port of the collimating AWG array, and is used to collimate the outgoing light / incident light.

[0022] Preferably, the spatial light modulator is a liquid crystal spatial light modulator, which is located at the rear focal plane of the lens group and is specifically configured as follows:

[0023] By controlling the voltage of each pixel electrode in different pixel areas, the optical signal of a wavelength channel is subjected to pure phase wavefront modulation, so that light of different wavelengths is deflected at different angles in the x-direction and returns to the original path in the y-direction.

[0024] Preferably, the lens group includes a cylindrical lens, an orthogonal biaxial aspheric lens, and a spherical lens, and is specifically configured as follows:

[0025] The cylindrical lens is used to converge the light beam in the x-direction and maintain the original propagation characteristics in the y-direction;

[0026] The ball lens is used to form a 2f system in the xz plane, converting offsets of different angles into off-axis displacements to achieve angle-spatial displacement conversion, and to form a 1:1 4f system with an orthogonal biaxial aspheric lens in the yz plane;

[0027] The orthogonal biaxial aspheric lens is used to form a 1:1 4f system with the spherical lens in the yz plane to control the size of the light spot in the y direction, and to form a 4f system with the cylindrical lens in the yz plane to achieve polarization multiplexing.

[0028] Preferably, the grating is located in the front focal plane of the ball lens and is specifically configured as follows:

[0029] Dispersing the linearly polarized light in the WDM signal into light of n wavelength channels dispersed along the x direction;

[0030] Optical signals of different frequencies are vertically incident on different areas of the spatial light modulator, and the light spots of the two WSS systems are distributed in the upper and lower parts of the spatial light modulator.

[0031] Preferably, the ports on one side of the AWG multi-waveguide are arranged in a rectangular array.

[0032] The present disclosure provides an integrable wide spectrum dense channel WSS based on liquid crystal spatial light modulator, which has the advantages that the axisymmetric AWG array is used as the input port / output port of the WSS to disperse the input WDM signal and combine the output optical signal, which can effectively process optical signals of different wavelengths and realize the separation of narrow-interval wavelengths; the polarization control module is used to convert the WDM signal into two beams of linearly polarized light in a single polarization state, which can realize fine control of the optical signal, so that more channels can be integrated in a limited space, significantly improve the channel density, optimize the spatial distribution of the optical signal, ensure low crosstalk between dense channels, and improve the integration and communication capacity of the system; the grating is used to convert the linearly polarized light in the WDM signal along the x-direction The system utilizes a 4f system for polarization multiplexing in the xz plane and a 2f system for converting offsets of different angles into off-axis displacements for angular-spatial displacement conversion. In the yz plane, a 1:1 4f system is used to control the spot size, enabling precise control of optical signal routing and distribution. This enhances the system's adaptability and configurability, facilitating dynamic adjustments to meet diverse network architectures and service requirements. The spatial light modulator performs pure phase wavefront modulation on the optical signal, causing light of different wavelengths to be deflected at different angles in the x-direction and returned along the original path in the y-direction, achieving angular-spatial displacement conversion and spot size control, respectively. This optimizes optical path transmission characteristics, reduces optical signal distortion and loss, and improves optical signal coupling efficiency and transmission quality. This optical path design enables the system to maintain high stability and reliability during signal transmission, reduces overall system power consumption, and enhances overall system performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate one or more embodiments of this specification or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 A schematic diagram of the structure of an integrated wide spectrum dense channel WSS based on a liquid crystal spatial light modulator provided in one or more embodiments of this specification;

[0035] Figure 2 A schematic diagram of the optical path principle of an integrated wide spectrum dense channel WSS based on a liquid crystal spatial light modulator provided in one or more embodiments of this specification is provided. Figure 2 (a) is the side view of the yz plane, Figure 2 (b) is the top view in the xz plane;

[0036] Figure 3 An axisymmetric AWG array arrangement diagram provided for one or more embodiments of this specification;

[0037] Figure 4 A schematic diagram of polarization control provided for one or more embodiments of this specification;

[0038] Figure 5 A schematic diagram of light spot distribution on a liquid crystal spatial light modulator provided in one or more embodiments of this specification. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below in conjunction with the drawings in one or more embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this invention document.

[0040] The present invention will be described in detail below with reference to specific implementation methods and the accompanying drawings.

[0041] Method Example

[0042] According to an embodiment of the present invention, an integrable wide spectrum dense channel WSS based on liquid crystal spatial light modulator is provided. Figure 1 As shown in FIG, a schematic diagram of the structure of the integrated wide spectrum dense channel WSS based on the liquid crystal spatial light modulator provided in this embodiment is shown in FIG. Figure 2 FIG. 1 is a schematic diagram of an optical path principle of an integrated wide spectrum dense channel WSS based on a liquid crystal spatial light modulator provided in this embodiment. Figure 2 (a) is the side view of the yz plane, Figure 2 (b) is a top-down view of the xz plane. The WDM light is first dispersed by an AWG in the center of the array and split into m beams of WDM light. Yz planes 4 and 6 form a 4f system to ensure that the spot size on plane 7 is consistent with that on plane 3. The polarization state of the xz plane is controlled by polarization multiplexing modules 3, 8, 4, and 9. The m beams of WDM light pass through the grating, and each beam is further split into n beams of single wavelength light. Ultimately, a matrix of m×n channels is formed on plane 7 (m×n channels is the maximum number of channels supported by the WSS system. In actual WSS applications, there may be fewer than m×n channels, but the position of each wavelength on plane 7 is fixed). The seven pairs of light of different wavelengths are then deflected in the x direction and ultimately combined by different AWGs at the output end, achieving optical switching at different output ports.

[0043] Two WSSs are integrated with a liquid crystal spatial light modulator. The WDM signal is incident from the input end of the WSS system, dispersed by the AWG, and several WDM signals are emitted from the fiber array at the output end of the AWG. The frequency of each channel is spaced apart by the FSR spectrum width. After passing through the collimating lens array and cylindrical lens, the polarization is controlled by the Wollaston prism and half-wave plate. The optical signals are separated by the lateral dispersion of the grating, and the multiple optical signals spaced apart by the FSR spectrum width are finally incident vertically on different areas of the liquid crystal spatial light modulator. The light spots of the two WSS systems are distributed in the upper and lower parts of the liquid crystal spatial light modulator, which can be flexibly controlled for different areas. The liquid crystal spatial light modulator modulates the wavefront of the light beam, forming reflection and deflection at different angles. After passing through the 2f system composed of lenses, the offsets of different angles are converted into off-axis displacements. Then, they are combined by the grating and output AWG respectively to realize the allocation of any wavelength to any output port. The two integrated WSS systems do not interfere with each other.

[0044] The integrable wide spectrum dense channel WSS based on liquid crystal spatial light modulator according to an embodiment of the present invention includes an axisymmetric AWG array 1 , a polarization control module, a grating 5 , a lens group and a spatial light modulator 7 .

[0045] The axisymmetric AWG array 1 is used as the input port / output port of the WSS. It consists of a group of AWG arrays arranged in parallel. The ports are bonded to optical fibers for transmission in the form of optical fibers. The input WDM signals are dispersed and the output optical signals are combined.

[0046] The polarization control module is used to convert the WDM signal into two beams of linearly polarized light with a single polarization state.

[0047] The grating 5 is used to disperse the linearly polarized light in the WDM signal along the x-direction.

[0048] The lens group is used to realize polarization multiplexing using the 4f system in the xz plane, and to convert the offsets of different angles into off-axis displacements using the 2f system to realize angle-spatial displacement conversion. The spot size is controlled by a 1:1 4f system in the yz plane to facilitate integration. Optical signals of different frequencies are vertically incident on different areas of the liquid crystal spatial light modulator 7, and the spots of the two WSS systems are distributed in the upper and lower parts of the liquid crystal spatial light modulator 7.

[0049] The spatial light modulator 7 is used to perform pure phase wavefront modulation on the optical signal, so that light of different wavelengths is deflected at different angles in the x-direction and returns along the original path in the y-direction.

[0050] The WSS provided in this embodiment uses the axially symmetric AWG array 1 as the input port / output port of the WSS to disperse the input WDM signal and combine the output optical signal, which can effectively process optical signals of different wavelengths, achieve coverage of a wide spectrum range, and meet the requirements of multi-wavelength optical communication systems for efficient use of spectrum resources; the polarization control module is used to convert the WDM signal into two beams of linearly polarized light in a single polarization state, which can achieve fine control of the optical signal, so that more channels can be integrated in a limited space, significantly improve the channel density, optimize the spatial distribution of the optical signal, ensure low crosstalk between dense channels, and improve the system's integration and communication capacity; the grating 5 is used to disperse the linearly polarized light in the WDM signal along the x-direction, which can reduce the loss and interference caused by the change of polarization state during the transmission of the optical signal, and improve the optical signal The stability and transmission quality of the optical signal are guaranteed, ensuring the efficient processing of optical signals by the entire system and reducing the bit error rate of signal transmission. The lens assembly is used to implement polarization multiplexing in the xz plane using a 4f system, and to convert offsets of different angles into off-axis displacements using a 2f system to achieve angle-to-spatial displacement conversion. In the yz plane, a 1:1 4f system is used to control the spot size, achieving precise control of optical signal routing and distribution. This enhances the adaptability and configurability of the system and facilitates dynamic adjustment to meet different network architectures and service requirements. The spatial light modulator 7 is used to perform pure phase wavefront modulation on the optical signal, causing light of different wavelengths to be deflected at different angles in the x direction and return along the original path in the y direction, achieving angle-to-spatial displacement conversion and spot size control, respectively. This optimizes the optical path transmission characteristics, reduces optical signal distortion and loss, and improves the coupling efficiency and transmission quality of the optical signal. This optical path design enables the system to maintain high stability and reliability during signal transmission, reduces overall system power consumption, and improves the overall system performance.

[0051] In one embodiment, Figure 3 As shown in FIG. 1 , the arrangement diagram of the axisymmetric AWG array 1 provided in this embodiment is shown. The axisymmetric AWG array 1 is composed of two groups of AWG arrays arranged in an axisymmetric manner. Each group of AWG arrays includes an input AWG array and several output AWG arrays. The input AWG array is located in the middle of the array, and the output AWG arrays are arranged in parallel and at equal intervals on both sides. The same AWG port is located along the y direction, and different AWG ports are located at the same position along the x direction.

[0052] The input port / output port of the axisymmetric AWG array 1 transmits light in the form of optical fiber ports. The strip waveguides of the AWG array are all connected to optical fibers. The ports on one side of the AWG waveguide are arranged in a rectangular array. The ports at the same position of different AWGs are arranged in sequence along the x-direction. The ports on one side of the AWG output planar waveguide are arranged in sequence along the y-direction.

[0053] The WSS provided in this embodiment achieves a highly integrated and compact structure, facilitating efficient connection with external optical communication equipment. The standardized and orderly port arrangement reduces the complexity of optical signal management and connection, improves the maintainability and scalability of the system, and optimizes the transmission path and layout of optical signals, laying the foundation for efficient optical signal processing and routing.

[0054] In one embodiment, dispersing an input WDM signal specifically includes the following steps:

[0055] The input WDM signal is dispersed by the AWG array and decomposed into m narrow-channel-spaced WDM signals arranged along the y direction at the m output ports of the AWG array. Each output port of the AWG array contains n wavelength channels with a pairwise spacing of FSR spectrum width.

[0056] The WSS provided in this embodiment realizes the refined decomposition of WDM signals, greatly improving channel utilization and meeting the optical communication system's demand for large-capacity, high-density data transmission. Through this precise dispersion method, optical signals of different wavelengths can be accurately separated and managed, laying a solid foundation for subsequent flexible routing of optical signals, wavelength selection and other operations, and enhancing the flexibility and accuracy of optical signal processing. The setting of narrow channel spacing and specific spectrum width wavelength channels effectively expands the transmission spectrum range, enabling the system to have wide-spectrum transmission capabilities, better adapting to the continuous development trend of modern optical communication technology, and improving the overall performance and application value of the system.

[0057] In one embodiment, Figure 4 , which is a schematic diagram of polarization control provided by this embodiment, wherein the polarization control module is composed of a Wollaston prism, a convex lens with an x-direction focal length of 0.5f, and several half-wave plates, and is specifically configured as follows:

[0058] The WDM signal is split into two linearly polarized beams with orthogonal polarization states through a Wollaston prism. One of the linearly polarized beams is converted into a linearly polarized light with the same polarization state as the other linearly polarized beam through a half-wave plate, so that the signal can be modulated by the liquid crystal device and then decomposed by the grating 5 into n wavelength channels of light dispersed along the x-direction.

[0059] The WSS provided in this embodiment can achieve precise control of the polarization state of optical signals and separation of wavelength channels, providing unified and standardized input conditions for subsequent optical signal processing, thereby improving the accuracy and efficiency of optical signal processing.

[0060] In one embodiment, a fiber collimating lens array is further included, wherein each collimating lens in the fiber collimating lens array corresponds to the outgoing light / incident light of an optical fiber port at the input port / output port of the collimating AWG array, and is used to collimate the outgoing light / incident light.

[0061] The WSS provided in this embodiment can effectively reduce the divergence loss of optical signals during transmission, improve the coupling efficiency of optical signals, enhance the stability and strength of signal transmission, ensure that optical signals enter subsequent optical modules in a regular and parallel state, and enable each optical component to more efficiently and accurately perform dispersion, modulation and other processing on the optical signals, thereby improving the performance and reliability of the entire WSS system and ensuring the accuracy and quality of wide-spectrum dense channel optical signal processing.

[0062] In one embodiment, Figure 5 FIG. 1 is a schematic diagram of the light spot distribution on the liquid crystal spatial light modulator 7 provided in this embodiment. The spatial light modulator 7 is a liquid crystal spatial light modulator located at the rear focal plane of the lens group, and is specifically configured as follows:

[0063] By controlling the voltage of each pixel electrode in different pixel areas, the optical signal of a wavelength channel is subjected to pure phase wavefront modulation, so that light of different wavelengths is deflected at different angles in the x-direction and returns to the original path in the y-direction.

[0064] The WSS provided in this embodiment lays the foundation for the wavelength selective switch to achieve flexible and accurate optical signal routing and distribution through precise optical signal manipulation, effectively improving the accuracy and efficiency of optical signal processing in optical communication systems.

[0065] In one embodiment, the lens group includes a cylindrical lens, an orthogonal biaxial aspheric lens, and a spherical lens, and is specifically configured as follows:

[0066] The cylindrical lens is used to converge the light beam in the x direction and maintain the original propagation characteristics in the y direction.

[0067] The ball lens is used to form a 2f system in the xz plane, converting offsets of different angles into off-axis displacements to achieve angle-spatial displacement conversion, and to form a 1:1 4f system with an orthogonal biaxial aspheric lens in the yz plane.

[0068] The orthogonal biaxial aspheric lens is used to form a 1:1 4f system with the spherical lens in the yz plane to control the size of the light spot in the y direction, and to form a 4f system with the cylindrical lens in the yz plane to achieve polarization multiplexing.

[0069] The WSS provided in this embodiment uses a cylindrical lens to converge the light beam in the x-direction while maintaining the original propagation characteristics in the y-direction, laying the foundation for subsequent differentiated processing of the light beam in different directions. The spherical lens and the cylindrical lens work together to form a 2f system in the xz plane. This system can convert offsets of different angles into off-axis displacements, achieving angle-to-spatial displacement conversion. This allows the spatial distribution of the optical signal to be effectively adjusted according to the angle change, facilitating precise routing of the optical signal. The orthogonal biaxial aspheric lens and the spherical lens form a 1:1 4f system in the yz plane, precisely controlling the size of the light spot in the y-direction, ensuring the transmission quality of the optical signal in this direction and making the spatial distribution of the optical signal more regular. This effectively avoids problems such as light spot deformation and dispersion, improves the accuracy and stability of optical signal processing, and provides a strong guarantee for the efficient and reliable implementation of wavelength selective switching functions for wide-spectrum dense channels in the entire system.

[0070] In one embodiment, the grating 5 is located at the front focal plane of the ball lens and is specifically configured as follows:

[0071] The linearly polarized light in the WDM signal is dispersed into light of n wavelength channels dispersed along the x direction.

[0072] Optical signals of different frequencies are vertically incident on different areas of the spatial light modulator 7 , and the light spots of the two WSS systems are distributed in the upper and lower parts of the spatial light modulator 7 .

[0073] In the WSS provided in this embodiment, the grating 5 is located in the front focal plane of the spherical lens. Its function is to disperse the linearly polarized light in the WDM signal into light of n wavelength channels distributed along the x-direction, so that optical signals of different frequencies are vertically incident on different areas of the spatial light modulator 7. In addition, the light spots of the two WSS systems can be distributed in the upper and lower parts of the spatial light modulator 7, respectively, to achieve effective separation and targeted processing of the optical signals, provide a basis for the subsequent modulation of the optical signals by the spatial light modulator 7, ensure the accurate transmission and control of optical signals of different wavelengths in the system, and help improve the wavelength selection accuracy and optical signal processing efficiency of the entire WSS system.

[0074] The following is further explained through specific implementation cases:

[0075] Example 1:

[0076] By integrating two WSSs with a liquid crystal spatial light modulator 7, more WSSs can be integrated by further controlling the spot size in the y direction of the liquid crystal spatial light modulator 7 or using a liquid crystal spatial light modulator 7 with a higher resolution. Figure 3As shown in the figure, the AWG arrays of the two WSS systems are arranged in an axisymmetric manner; one end of the AWG single waveguide serves as the input / output port of the WSS, and the ports on the AWG multi-waveguide side are arranged in a rectangular array, with the same AWG port along the y direction and different AWG ports at the same position along the x direction; the strip waveguides of the AWG are all connected to optical fibers. Figure 2 As shown in the figure, the input WDM signal is dispersed by the AWG and decomposed into m narrow channel spacing WDM signals arranged along the y direction at the m output ports of the AWG. Each AWG output port contains n wavelength channels with two-by-two spacing of FSR spectrum width. After that, each beam of light passes through the collimating lens and then passes through the Figure 4 The polarization control structure shown is composed of a Wollaston prism, a convex lens with a focal length of 0.5f in the x-direction, and several half-wave plates. Natural light is divided into two linearly polarized beams with orthogonal polarization directions by the Wollaston prism. One beam is converted into a linearly polarized beam with the same polarization state as the other beam by the half-wave plate, so that the signal can be modulated by the liquid crystal device; it is then decomposed by the grating 5 into n wavelength channels of light dispersed along the x-direction. In the yz plane, the orthogonal biaxial aspheric lens and the spherical lens form a 1:1 4f system to control the y-direction size of the light spot on the liquid crystal device for easy integration. The wavelength channel distribution on the liquid crystal spatial light modulator 7 of this system is shown as follows: Figure 5 As shown, on the plane of the liquid crystal spatial light modulator 7, by controlling the voltage of each pixel electrode in different pixel regions, pure phase wavefront modulation is performed on the light. This causes light of different wavelengths to be deflected at different angles in the x-direction and return along the original path in the y-direction. The reflected light passes through a 2f system composed of spherical lenses with a focal length of f, converting the angular offset into a position offset along the x-direction. The light is then combined by a grating 5 and then by different AWGs corresponding to different output ports of the WSS, enabling the switching of optical signals of different wavelengths to any output port. Furthermore, the liquid crystal spatial light modulator 7 regulates the beams of the two WSS systems in different regions, ensuring that the two WSS systems do not interfere with each other. This system can support the integration of multiple WSSs, with each WSS supporting wide-band ultra-dense wavelength division multiplexing, enabling flexible interaction of a large number of channels. Its integrability and high capacity make it suitable for use as a key component in ROADM systems for terrestrial optical networks or relay nodes in space-based backbone networks for satellite laser communications, enabling flexible channel allocation.

[0077] Each embodiment in this specification is described in a progressive manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the device or system embodiments, since they are basically similar to the method embodiments, the description is relatively simple. For the relevant parts, refer to the partial description of the method embodiments. The device and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. A person of ordinary skill in the art can understand and implement it without making any creative efforts.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and the contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. An integrable wide spectrum dense channel WSS based on liquid crystal spatial light modulator, characterized in that: It includes an axisymmetric AWG array, a polarization control module, a grating, a lens group and a spatial light modulator; The axisymmetric AWG array is used as the input port / output port of the WSS to disperse the input WDM signal and combine the output optical signal; The polarization control module is used to convert the WDM signal into two beams of linearly polarized light with a single polarization state; The grating is used to disperse the linearly polarized light in the WDM signal along the x-direction; The lens assembly is used to achieve polarization multiplexing using a 4f system in the xz plane, convert offsets of different angles into off-axis displacements using a 2f system to achieve angle-spatial displacement conversion, and control the spot size in the yz plane using a 1:1 4f system; The spatial light modulator is used to perform pure phase wavefront modulation on the optical signal, so that light of different wavelengths is deflected at different angles in the x direction and returns along the original path in the y direction.

2. The integrable wide spectrum dense channel WSS based on liquid crystal spatial light modulator according to claim 1, characterized in that: The axisymmetric AWG array is composed of two groups of AWG arrays arranged in an axisymmetric manner. Each group of AWG arrays includes an input AWG and several output AWGs. The input AWG is located in the middle of the array, and the output AWGs are arranged in parallel and at equal intervals on both sides.

3. The integrable wide spectrum dense channel WSS based on liquid crystal spatial light modulator according to claim 1 or 2, characterized in that: The input port / output port of the axisymmetric AWG array is used for optical transmission in the form of optical fiber ports; The ports at the same position of different AWGs are arranged in sequence along the x-direction, and the ports on one side of the AWG output planar waveguide are arranged in sequence along the y-direction.

4. The integrable wide spectrum dense channel WSS based on liquid crystal spatial light modulator according to claim 1, characterized in that: The step of dispersing the input WDM signal specifically comprises the following steps: The input WDM signal is dispersed by the AWG array and decomposed into m narrow-channel-spaced WDM signals arranged along the y direction at the m output ports of the AWG array. Each output port of the AWG array contains n wavelength channels with a pairwise spacing of FSR spectrum width.

5. The integrable wide spectrum dense channel WSS based on liquid crystal spatial light modulator according to claim 1, characterized in that: The polarization control module is composed of a Wollaston prism and a half-wave plate, and is specifically configured as follows: The WDM signal is split into two linearly polarized beams with orthogonal polarization states through a Wollaston prism; One of the linearly polarized lights is converted into a linearly polarized light having the same polarization state as the other linearly polarized light by passing through a half-wave plate.

6. The integrable wide spectrum dense channel WSS based on liquid crystal spatial light modulator according to claim 1, characterized in that: It also includes a fiber collimating lens array, each collimating lens in the fiber collimating lens array corresponds to the outgoing light / incident light of an optical fiber port at the input port / output port of the collimating AWG array, and is used to collimate the outgoing light / incident light.

7. The integrable wide spectrum dense channel WSS based on liquid crystal spatial light modulator according to claim 1, characterized in that: The spatial light modulator is a liquid crystal spatial light modulator, located at the rear focal plane of the lens group, and is specifically configured as follows: By controlling the voltage of each pixel electrode in different pixel areas, the optical signal of a wavelength channel is subjected to pure phase wavefront modulation, so that light of different wavelengths is deflected at different angles in the x-direction and returns to the original path in the y-direction.

8. The integrable wide spectrum dense channel WSS based on liquid crystal spatial light modulator according to claim 1, characterized in that: The lens group includes a cylindrical lens, an orthogonal biaxial aspheric lens, and a spherical lens, and the specific configuration is as follows: The cylindrical lens is used to converge the light beam in the x-direction and maintain the original propagation characteristics in the y-direction; The ball lens is used to form a 2f system in the xz plane, converting offsets of different angles into off-axis displacements to achieve angle-spatial displacement conversion, and to form a 1:1 4f system with an orthogonal biaxial aspheric lens in the yz plane; The orthogonal biaxial aspheric lens is used to form a 1:1 4f system with the spherical lens in the yz plane to control the size of the light spot in the y direction, and to form a 4f system with the cylindrical lens in the yz plane to achieve polarization multiplexing.

9. The integrable wide spectrum dense channel WSS based on liquid crystal spatial light modulator according to claim 8, characterized in that: The grating is located at the front focal plane of the ball lens and is specifically configured as follows: Dispersing the linearly polarized light in the WDM signal into light of n wavelength channels dispersed along the x direction; Optical signals of different frequencies are vertically incident on different areas of the spatial light modulator, and the light spots of the two WSS systems are distributed in the upper and lower parts of the spatial light modulator.

10. The integrable wide spectrum dense channel WSS based on liquid crystal spatial light modulator according to claim 1, characterized in that: The ports on one side of the AWG waveguide are arranged in a rectangular array.

Images