A folded MxN port wavelength selective switch

Abstract

The application discloses a kind of folding M×N port wavelength selective switches, it is related to optical communication and optical signal processing field, by one-dimensional fiber array, input beam in optical fiber is converted into Gaussian beam, Gaussian beam successively passes short-focus cylindrical lens, first long-focus cylindrical lens and mirror, Gaussian beam is split into first beam and second beam with same polarization state after passing polarization beam splitting combination prism covered by the mirror, two beams of light are diffracted by first and second transmission type phase diffraction grating and pass second long-focus cylindrical lens to obtain first and second long-focus beams respectively, liquid crystal pattern loading control system loads phase gray scale map to light wave light field modulator according to the wavelength of first and second long-focus beams, changes the angle of diffraction angle of reflected light beam on x'z' plane, by adjusting light beam, the same polarization state of wavelength selective switch receiving optical signal is obtained, so that the energy loss of M×N port wavelength selective switch as a whole is reduced, and energy loss is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical communication and optical signal processing, in particular to a folded MxN port wavelength selective switch. BACKGROUND

[0002] With the rise of 5G / 6G, VR / AR and Internet related industries, traditional optical fiber communication network is facing great pressure from network throughput, energy consumption and operation and maintenance costs. In recent years, building the next generation of low energy consumption and high spectral efficiency intelligent all-optical communication network based on all-optical switching, multi-dimensional multiplexing, high spectral utilization rate super channel transmission and switching technology and software dynamic adjustment of network resources has gradually become an important consensus in the field of communication research and industry, and is one of the most important research hotspots and development directions in the field of current optical communication technology, which has extremely important research value and broad international market demand, and has attracted widespread attention from research institutions and device and equipment suppliers worldwide. Intelligent all-optical communication network based on reconfigurable optical add / drop multiplexer (ROADM, Reconfigurable Optical Add / Drop Multiplexer) and gridless flexible spectrum technology has been widely used in optical switching nodes due to its data rate transparency, low power consumption, low cost and high network resource utilization, and has become the main development direction of optical switching technology in current optical networks. The core optical engine wavelength selective switch (WSS, wavelength selective switch) in ROADM is the only all-optical signal processing and all-optical switching device with powerful signal processing function, and has become an indispensable important basic device for the all-optical and intelligent transformation of current and future global optical networks.

[0003] A large number of 1xN port WSSs (1 input port and N output ports) are used in existing optical switching nodes to achieve cross interconnection between M inputs and N outputs of multi-dimensional nodes, which has obvious disadvantages such as complex control system, high power consumption and cost, large insertion loss, limited passband and difficulty in upgrading. Therefore, directly using high port number MxN port WSS (M input ports and N output ports) to exchange optical signals of multi-dimensional nodes can greatly reduce the construction, operation and maintenance cost of optical switching nodes and the complexity of system composition, which is of great significance for the construction of future optical switching nodes.

[0004] The wavelength selective switch of M*N ports usually has M optical signal input ports and N optical signal output ports, and can realize the function of outputting any one or a group of wavelength signals of the optical signal of a certain port of the M input ports from any one or more ports of the N output ports. In recent years, major research institutions at home and abroad including Finisar, Lumentum, Huawei and the like have included the construction of the wavelength selective switch of M*N ports by using a liquid crystal spatial light modulator into the main research and development plan, but so far there is no commercialized wavelength selective switch of M*N ports. The technical scheme of the wavelength selective switch of M*N ports is faced with the key technical problems of the size limitation of the liquid crystal chip, the insufficient number of ports caused by the independence of the incident and exit ports, the complex optical path structure, the large insertion loss and the like, and there is no satisfactory technical scheme and experimental result at present. In the known M*N port WSS, the processing of the polarization state is not independent of the switching of the light beams between the input / output ports, the polarization processing is restricted by the number of WSS output ports, the energy loss of the overall system is increased, and the energy is lost. SUMMARY

[0005] The purpose of the present application is to provide a folded M*N port wavelength selective switch, so as to reduce the energy loss of the overall M*N port wavelength selective switch.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following scheme:

[0007] A folded M*N port wavelength selective switch, comprising:

[0008] A one-dimensional fiber array has M input ports and N output ports, each input port and each output port forms a one-dimensional array along the x-axis direction, and the M input ports are in the middle, and the N output ports are respectively located on both sides of the M input ports; the incident Gaussian light beams emitted by each input port and the exit Gaussian light beams entering the output port are transmitted along the z-axis direction;

[0009] A short-focus cylindrical lens, the incident Gaussian light beam passes through the short-focus cylindrical lens along the z-axis to form a short-focus Gaussian incident light beam;

[0010] A first long-focus cylindrical lens, the generatrix of the first long-focus cylindrical lens and the short-focus cylindrical lens are located on the xz plane, and the z-axis respectively passes through the generatrix of the first long-focus cylindrical lens and the short-focus cylindrical lens; the short-focus Gaussian incident light beam passes through the first long-focus cylindrical lens to obtain a long-focus Gaussian incident light beam;

[0011] A polarization beam splitting combination prism is placed perpendicular to the yz plane;

[0012] A mirror is arranged perpendicularly to the yz plane, a middle line of the mirror is parallel to the x axis, and the mirror covers part of the polarization beam splitting prism; the long-focus Gaussian incident light beam forms a first light beam and a second light beam with the same polarization state and parallel to the z axis after passing through the polarization beam splitting prism not covered by the mirror;

[0013] A first transmissive phase diffraction grating is arranged perpendicularly to the yz plane, and the first light beam passes through the first transmissive phase diffraction grating to obtain a first diffraction light beam;

[0014] A second transmissive phase diffraction grating is arranged perpendicularly to the yz plane, parallel to the first transmissive phase diffraction grating, and has a set distance from the first transmissive phase diffraction grating; the second light beam passes through the second transmissive phase diffraction grating to obtain a second diffraction light beam; the second diffraction light beam is parallel to the first diffraction light beam; wherein a transmission path of the first diffraction light beam is taken as a z' axis, an x axis is parallel to an x' axis, and a y' axis is perpendicular to an x'z' plane to establish an x'y'z' three-dimensional coordinate system;

[0015] A second long-focus cylindrical lens is arranged perpendicularly to the y'z' plane, a middle straight line of the first diffraction light beam and the second diffraction light beam is perpendicular to a central axis of the second long-focus cylindrical lens, and the central axis of the second long-focus cylindrical lens is perpendicular to the y'z' plane; the first diffraction light beam and the second diffraction light beam pass through the second long-focus cylindrical lens; the first diffraction light beam and the second diffraction light beam pass through the second long-focus cylindrical lens to perform beam collimation and chromatic dispersion compensation to obtain a first long-focus light beam and a second long-focus light beam;

[0016] A light wave optical field modulator is arranged corresponding to the second long-focus cylindrical lens and has M first light beam deflection regions and N second light beam deflection regions; each first light beam deflection region corresponds to each input port one by one, and each first light beam deflection region is centered; each second light beam deflection region corresponds to each output port one by one, and each second light beam deflection region is located on both sides of each first light beam deflection region; the light wave optical field modulator is used for reflecting the first long-focus light beam and the second long-focus light beam to obtain a first reflected light beam and a second reflected light beam, and converting a divergence state of the first reflected light beam and the second reflected light beam on the x axis into a parallel transmission state;

[0017] A liquid crystal pattern loading control system is connected with the light wave optical field modulator and is used for loading a phase grayscale pattern to the light wave optical field modulator according to wavelengths of the first long-focus light beam and the second long-focus light beam; the light wave optical field modulator is further used for changing an angle of a diffraction angle of the first reflected light beam and the second reflected light beam on the x'z' plane according to the phase grayscale pattern.

[0018] Preferably, the polarization beam splitting prism comprises:

[0019] a polarizing beam splitter, the mirror is placed close to the polarizing beam splitter, the mirror covers part of the polarizing beam splitter; the long-focus Gauss incident light beam is split into a first initial light beam of S polarization state and a second initial light beam of P polarization state after passing through the polarizing beam splitter not covered by the mirror;

[0020] a light path conversion mirror, corresponding to the polarizing beam splitter, used for deflecting the light path propagation angle of the first initial light beam of S polarization state to obtain the first light beam of S polarization state;

[0021] a half-wave plate, glued to the polarizing beam splitter, used for changing the P state of the second initial light beam to S polarization state to form the second light beam of S polarization state.

[0022] Optionally, the light path conversion mirror is a mirror or a right-angle prism.

[0023] Preferably, N is an even number, wherein, along the x-axis direction, N / 2 output ports are located above M input ports, and N / 2 output ports are located below M input ports, and the input ports and the output ports are symmetrically distributed.

[0024] Optionally, the light wave field modulator is a liquid crystal spatial light modulator.

[0025] Optionally, the liquid crystal spatial light modulator comprises three liquid crystal chips.

[0026] Preferably, the short-focus cylindrical lens is a cylindrical lens with a focal length of less than 50 mm.

[0027] Preferably, the first long-focus cylindrical lens and the second long-focus cylindrical lens are cylindrical lenses with a focal length of 100-200 mm.

[0028] Optionally, the one-dimensional optical fiber array is a one-dimensional single-mode optical fiber collimator array or a one-dimensional optical fiber array coupled micro-lens.

[0029] Optionally, the short-focus cylindrical lens, the first long-focus cylindrical lens and the second long-focus cylindrical lens are transmissive cylindrical lenses with anti-reflection film lenses or reflective cylindrical lenses.

[0030] According to the specific embodiments of the present application, the following technical effects are provided:

[0031] The application provides a folding M*N port wavelength selective switch, which converts an input light beam in an optical fiber into a Gaussian light beam through a one-dimensional optical fiber array, the Gaussian light beam passes through a short-focus cylindrical lens along a z axis to obtain a short-focus Gaussian incident light beam, the short-focus Gaussian incident light beam passes through a first long-focus cylindrical lens along the z axis to obtain a long-focus Gaussian incident light beam, and the long-focus Gaussian incident light beam is split into a first light beam and a second light beam with the same polarization state after passing through the polarization beam splitting combination prism covered by the reflector; the first light beam is diffracted to obtain a first diffracted light beam when passing through the first transmissive phase diffraction grating along the z axis, and the second light beam is diffracted to obtain a second diffracted light beam when passing through the second transmissive phase diffraction grating along the z axis, and the first diffracted light beam and the second diffracted light beam are parallel; the first diffracted light beam and the second diffracted light beam pass through the second long-focus cylindrical lens, and the first diffracted light beam and the second diffracted light beam are collimated and dispersion-compensated by the second long-focus cylindrical lens to obtain a first long-focus light beam and a second long-focus light beam to the optical wave light field modulator; a liquid crystal pattern loading control system is connected with the optical wave light field modulator, the liquid crystal pattern loading control system loads a phase gray scale pattern according to the wavelengths of the first long-focus light beam and the second long-focus light beam, the optical wave light field modulator reflects the first long-focus light beam and the second long-focus light beam to obtain a first reflected light beam and a second reflected light beam, changes the angle of the diffraction angle of the first reflected light beam and the second reflected light beam, and simultaneously converts the slightly divergent state of the first reflected light beam and the second reflected light beam on the x axis into a parallel transmission state, so that the energy loss of the M*N port wavelength selective switch as a whole is reduced through multiple adjustments of the light beam. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0033] Figure 1 It is a perspective structural schematic diagram of the folding M*N port wavelength selective switch of the present application.

[0034] Figure 2 It is an optical axis transmission schematic diagram of different wavelength light beams of the folding M*N port wavelength selective switch of the present application.

[0035] Figure 3 It is a spot size transmission schematic diagram of a single wavelength light beam of the folding M*N port wavelength selective switch of the present application.

[0036] Figure 4Schematic diagram of the deflection angle of the optical axis when the liquid crystal spatial light modulator deflects the light beam for the first time and deflects the light beam for the second time in the xz plane of the folded M×N port wavelength selective switch (in order to clearly show the light beam transmission path, the reflective liquid crystal spatial light modulator is represented as transmissive, and the incident angle and the diffraction angle of the transmissive phase diffraction grating are ignored);

[0037] Figure 5 Schematic diagram of the change in the size of the light beam when the liquid crystal spatial light modulator deflects the light beam for the first time and deflects the light beam for the second time in the xz plane of the folded M×N port wavelength selective switch (in order to clearly show the corresponding size change of the light beam, the reflective liquid crystal spatial light modulator is represented as transmissive, and the incident angle and the diffraction angle of the transmissive phase diffraction grating are ignored);

[0038] Figure 6 Schematic diagram of the deflection angle of the optical axis when the liquid crystal spatial light modulator deflects the light beam for the first time and deflects the light beam for the second time in the xz plane of the folded M×N port wavelength selective switch (in order to clearly show the light beam transmission path, the reflective liquid crystal spatial light modulator is represented as transmissive, and the incident angle and the diffraction angle of the transmissive phase diffraction grating are ignored);

[0039] Symbol explanation:

[0040] One-dimensional optical fiber array-1, short focal cylindrical lens-2 first long focal cylindrical lens-3, optical path conversion mirror-4, mirror-5, polarization beam splitting prism-6, half-wave plate-7, first transmissive phase diffraction grating-8, second transmissive phase diffraction grating-9, second long focal cylindrical lens-10, optical wave field modulator-11, liquid crystal pattern loading control system-12. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0042] The purpose of the present application is to provide a folded M×N port wavelength selective switch, which separates the polarization state processing from the switching of the light beams between the input / output ports, solves the polarization processing constraint on the number of WSS output ports in the reported M×N port WSS, and completely eliminates the limitation of polarization conversion processing on the number of optical fiber ports that can be accommodated by the wavelength selective switch, so that the overall energy loss of the M×N port wavelength selective switch is reduced.

[0043] In order to make the above-mentioned purposes, characteristics and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0044] As Figure 1 shown in the figure, the folding M×N port wavelength selective switch of the present application comprises: a one-dimensional fiber array 1, a short-focus cylindrical lens 2, a first long-focus cylindrical lens 3, a mirror 5, a polarization beam splitting and combining prism, a first transmissive phase diffraction grating 8, a second transmissive phase diffraction grating 9, a second long-focus cylindrical lens 10, a light wave field modulator 11, and a liquid crystal pattern loading control system 12.

[0045] Specifically, the one-dimensional fiber array 1 has M input ports and N output ports, each input port and each output port form a one-dimensional array along the x-axis direction, and the M input ports are in the middle, and the N output ports are respectively located on both sides of the M input ports; the incident Gaussian light beams emitted by each input port and the outgoing Gaussian light beams entering the output port are transmitted along the z-axis direction.

[0046] The incident Gaussian light beams pass through the short-focus cylindrical lens 2 along the z-axis to form short-focus Gaussian incident light beams.

[0047] The generatrix of the first long-focus cylindrical lens 3 and the short-focus cylindrical lens 2 are both located on the xz plane, and the z-axis passes through the generatrix of the first long-focus cylindrical lens 3 and the short-focus cylindrical lens 2, respectively; the short-focus Gaussian incident light beams pass through the first long-focus cylindrical lens 3 to obtain long-focus Gaussian incident light beams. The short-focus cylindrical lens 2 and the first long-focus cylindrical lens 3 form an optical 4f system.

[0048] In this embodiment, the short-focus cylindrical lens 2 is a cylindrical lens with a focal length of 50 mm or less. The first long-focus cylindrical lens 3 and the second long-focus cylindrical lens 10 are cylindrical lenses with a focal length of 100 mm-200 mm. The focal lengths of the short-focus cylindrical lens 2, the first long-focus cylindrical lens 3 and the second long-focus cylindrical lens 10 are determined according to actual needs.

[0049] The polarization beam splitting and combining prism is placed perpendicular to the yz plane.

[0050] The mirror 5 is placed perpendicular to the yz plane, the center line of the mirror 5 is parallel to the x-axis, and covers part of the polarization beam splitting and combining prism; after the long-focus Gaussian incident light beams pass through the polarization beam splitting and combining prism not covered by the mirror 5, first light beams and second light beams with the same polarization state and parallel to the z-axis are formed.

[0051] Preferably, the mirror 5 covers half of the polarization beam splitting and combining prism.

[0052] The first transmissive phase diffraction grating 8 is placed perpendicular to the yz plane, and the first light beams pass through the first transmissive phase diffraction grating 8 to obtain first diffraction light beams.

[0053] The second transmissive phase diffraction grating 9 is placed perpendicularly to the yz plane, parallel to the first transmissive phase diffraction grating 8, and has a set distance from the first transmissive phase diffraction grating 8; the second light beam passes through the second transmissive phase diffraction grating 9 to obtain a second diffraction light beam; the second diffraction light beam is parallel to the first diffraction light beam; wherein the transmission path of the first diffraction light beam is the z' axis, the x axis is parallel to the x' axis, and the y' axis is perpendicular to the x'z' plane, to establish an x'y'z' three-dimensional coordinate system.

[0054] The incidence angle and diffraction angle of the first light beam and the second light beam are related to the number of ruling lines on the corresponding transmissive phase diffraction grating. By adjusting the placement position of the first transmissive phase diffraction grating 8 and the second transmissive phase diffraction grating 9, the optical path difference generated by the first light beam and the second light beam when the polarization beam splitting combination prism splits light can be compensated.

[0055] The second long-focus cylindrical lens 10 is placed perpendicularly to the y'z' plane, the central axis of the second long-focus cylindrical lens 10 is perpendicular to the intermediate straight line of the first diffraction light beam and the second diffraction light beam, and the central axis of the second long-focus cylindrical lens 10 is perpendicular to the y'z' plane, and the first diffraction light beam and the second diffraction light beam pass through the second long-focus cylindrical lens 10; the first diffraction light beam and the second diffraction light beam pass through the second long-focus cylindrical lens to perform beam collimation and chromatic dispersion compensation to obtain a first long-focus light beam and a second long-focus light beam.

[0056] The first diffraction light beam and the second diffraction light beam can all be incident to the second long-focus cylindrical lens 10.

[0057] The light wave optical field modulator 11 is arranged corresponding to the second long-focus cylindrical lens 10, and has M first light beam deflection regions and N second light beam deflection regions, each first light beam deflection region corresponds to each input port one by one, and each first light beam deflection region is centered; each second light beam deflection region corresponds to each output port one by one, and each second light beam deflection region is located on both sides of each first light beam deflection region; the light wave optical field modulator 11 is used for reflecting the first long-focus light beam and the second long-focus light beam to obtain a first reflected light beam and a second reflected light beam, and changing the diffraction angle of the first reflected light beam and the second reflected light beam, i.e. the diffraction angle in the x'z' plane; at the same time, the slightly divergent state of the first reflected light beam and the second reflected light beam in the x axis is converted into a parallel transmission state.

[0058] The light wave optical field modulator 11 is placed perpendicularly to the x'z' and y'z' planes, and parallel to the x'y' plane.

[0059] The liquid crystal pattern loading control system 12 is connected with the light wave light field modulator 11, and is used for loading a phase gray scale pattern to the light wave light field modulator 11 according to the wavelengths of the first long-focus light beam and the second long-focus light beam; the light wave light field modulator 11 is further used for changing the angles of the diffraction angles of the first reflected light beam and the second reflected light beam on the x'z' plane according to the phase gray scale pattern.

[0060] The reflecting mirror 5 is placed in contact with the polarization beam splitting prism 6, and the reflecting mirror 5 covers part of the polarization beam splitting prism 6; the long-focus Gaussian incident light beam is split into a first initial light beam in S polarization state and a second initial light beam in P polarization state after passing through the polarization beam splitting prism 6 which is not covered by the reflecting mirror 5, and the edge line of the reflecting mirror 5 coincides with the middle line of the polarization beam splitting prism 6.

[0061] The light path conversion mirror 4 is arranged corresponding to the polarization beam splitting prism 6, and is used for deflecting the light path propagation angle of the first initial light beam in S polarization state to obtain the first light beam in S polarization state.

[0062] The half-wave plate 7 is glued with the polarization beam splitting prism 6, and is used for changing the P state of the second initial light beam into S polarization state to form the second light beam in S polarization state.

[0063] When the light beam enters the wavelength selection switch, the wavelength selection switch will only act on the light signal of one polarization state, and half of the energy of the light signal carried by the other polarization state will be lost. The polarization state of the second initial light beam is changed by the polarization beam splitting combination prism, so that the energy loss problem is solved.

[0064] Optionally, the light path conversion mirror 4 is a reflecting mirror or a right-angle prism.

[0065] According to actual needs, N is an even number, wherein, along the x-axis direction, N / 2 output ports are located above M input ports, and N / 2 output ports are located below the M input ports, and the input ports and the output ports are symmetrically distributed.

[0066] Optionally, the light wave light field modulator 11 is a liquid crystal spatial light modulator.

[0067] Optionally, the liquid crystal spatial light modulator comprises three liquid crystal chips, wherein one liquid crystal chip corresponds to M input ports, and the other two correspond to N / 2 output ports; according to the required number of ports, the number of liquid crystal chips is continuously expanded, and the surface of each liquid crystal chip is a two-dimensional pixel array.

[0068] When the number of liquid crystal spatial light modulators is n, the number of liquid crystal chips is n.

[0069] Optionally, the one-dimensional optical fiber array 1 is a one-dimensional single-mode optical fiber collimator array or a one-dimensional optical fiber array 1 coupling micro-lens. Both the one-dimensional single-mode optical fiber collimator array and the one-dimensional optical fiber array 1 coupling micro-lens can achieve the same Gaussian beam output effect. The number of ports of the one-dimensional single-mode optical fiber collimator array is the same as the number of one-dimensional single-mode optical fiber collimators.

[0070] Optionally, the short-focus cylindrical mirror 2, the first long-focus cylindrical mirror 3, and the second long-focus cylindrical mirror 10 are transmission cylindrical mirrors inlaid with anti-reflection film lenses or reflective cylindrical mirrors.

[0071] The embodiment of the folded MxN port wavelength selective switch of the present application is as follows:

[0072] 1) Optical path building (as shown in Figure 3

[0073] a. The one-dimensional optical fiber array 1, the short-focus cylindrical mirror 2, the first long-focus cylindrical mirror 3, the mirror 5, the polarization beam splitting combined prism, the first transmission type phase diffraction grating 8, the second transmission type phase diffraction grating 9, the second long-focus cylindrical mirror 10, the liquid crystal spatial light modulator, and the liquid crystal pattern loading control system 12 are sequentially arranged along the direction of beam transmission.

[0074] b. The one-dimensional optical fiber array 1 has M input ports and N output ports, each input port and each output port form a one-dimensional array along the x-axis direction; and the M input ports are in the center, and the N output ports are respectively located on both sides of the M input ports; the incident Gaussian beam emitted by each input port and the outgoing Gaussian beam entering the output port are both transmitted along the z-axis direction.

[0075] c. The generatrix of the short-focus cylindrical mirror 2 and the first long-focus cylindrical mirror 3 is located on the xz plane, and the z-axis passes through the generatrix of the short-focus cylindrical mirror 2 and the first long-focus cylindrical mirror 3 respectively; the incident Gaussian beam passes through the short-focus cylindrical mirror 2 along the z-axis to form a short-focus Gaussian incident beam; the short-focus Gaussian incident beam passes through the first long-focus cylindrical mirror 3 to obtain a long-focus Gaussian incident beam; the short-focus cylindrical mirror 2 and the first long-focus cylindrical mirror 3 form an optical 4f system.

[0076] d. The polarization beam splitting combined prism is placed perpendicular to the yz plane, and is composed of a polarization beam splitting prism 6, an optical path conversion mirror 4, and a half-wave plate 7; the mirror 5 is placed in close contact with the polarization beam splitting prism 6, and the edge line on one side of the mirror 5 is flush with the middle line of the polarization beam splitting prism 6; the half-wave plate 7 is glued with the polarization beam splitting prism 6; after the long-focus Gaussian incident beam passes through the polarization beam splitting combined prism which is not covered by the mirror 5, a first beam and a second beam with the same polarization state and parallel to the z-axis are formed.

[0077] ​e. Both the first transmissive phase diffraction grating 8 and the second transmissive phase diffraction grating 9 are placed perpendicular to the yz plane, and there is a set distance between the second transmissive phase diffraction grating 9 and the first transmissive phase diffraction grating 8; the first beam passes through the first transmissive phase diffraction grating 8 to obtain a first diffracted beam; the second beam passes through the second transmissive phase diffraction grating 9 to obtain a second diffracted beam; the second diffracted beam is parallel to the first diffracted beam.

[0078] f. The second telephoto cylindrical mirror 10 is placed perpendicular to the y'z' plane. The middle line of the first diffracted beam and the second diffracted beam is perpendicular to the central axis of the second telephoto cylindrical mirror, and the central axis of the second telephoto cylindrical mirror 10 is perpendicular to the y'z' plane. The first diffracted beam and the second diffracted beam pass through the second telephoto cylindrical mirror 10. The first diffracted beam and the second diffracted beam are parallel and collimated and have dispersion compensated by the second telephoto cylindrical mirror to obtain the first telephoto beam and the second telephoto beam.

[0079] g. An optical field modulator 11 is configured corresponding to the second telephoto cylindrical mirror 10, and has M first beam deflection regions and N second beam deflection regions. Each first beam deflection region corresponds one-to-one with each input port and is centered. Each second beam deflection region corresponds one-to-one with each output port and is located on both sides of each first beam deflection region. The optical field modulator 11 is used to reflect the first telephoto beam and the second telephoto beam to obtain a first reflected beam and a second reflected beam.

[0080] h. such as Figure 5 As shown, the liquid crystal graphic loading control system 12 is connected to the optical wave field modulator 11 and is used to control the optical wave field modulator 11 by loading a phase grayscale image according to the wavelengths of the first long focal beam and the second long focal beam, thereby forming a phase holographic grating; the multiple liquid crystal chips of the optical wave field modulator 11 are divided into M+N regions, and the M regions correspond one-to-one with the M input ports. The M regions are the first reflection regions, labeled as T1, T2...T M The M regions are located at the center of the optical field modulator 11; the N regions correspond one-to-one with the N output ports, and the N regions are the second reflection regions, labeled K1, K2...K N M and N are both natural numbers ≥ 2, and the input ports and output ports are symmetrically distributed.

[0081] 2) M independent incident beams of continuous wavelength are input into M input ports respectively;

[0082] 3) The M input ports will output M Gaussian beams that propagate independently and in parallel along the z-axis. The optical axes of the M Gaussian beams pass through the generatrix of the short focal length cylindrical mirror 2 and the generatrix of the first long focal length cylindrical mirror 3. By adjusting the focal lengths of the short focal length cylindrical mirror 2 and the first long focal length cylindrical mirror 3, the M outgoing beams are expanded and collimated into parallel beams along the y-axis. The short focal length cylindrical mirror 2 and the first long focal length cylindrical mirror 3 increase the size of the M beams in the y-axis direction, but have no effect on the size of the M beams in the x-axis direction.

[0083] 4) M long-focal Gaussian beams are split into M first beams and M second beams after passing through a polarization beam splitter. Both the first and second beams are S-polarized and propagate parallel to the z-axis. The first and second beams are separated along the y-axis and have a distance difference.

[0084] 5) The following specific embodiment uses a single Gaussian beam, where the first beam and the second beam are respectively incident on the first transmission phase diffraction grating 8 and the second transmission phase diffraction grating 9; as shown... Figure 2 As shown, the first transmissive phase diffraction grating 8 disperses the light of various wavelengths contained in the first beam to obtain the first diffracted beam, and the second transmissive phase diffraction grating 9 disperses the light of various wavelengths contained in the second beam to obtain the second diffracted beam, and transmits the first diffracted beam and the second diffracted beam to the second telephoto cylindrical mirror 10.

[0085] 6) The optical axis of the second telephoto cylindrical lens 10 is located between the first beam and the second beam; the second telephoto cylindrical lens 10 converts the first diffracted beam and the second diffracted beam into parallel beams that propagate parallel to each other along the optical axis of the y'z' plane, and projects the single-wavelength beams onto the optical field modulator 11, and deflects these parallel beams as a whole toward the centerline of the optical field modulator 11. At the same time, the second telephoto cylindrical lens 10 narrows the original elliptical beam with the y' axis as the major axis into an elliptical beam with the x' axis as the major axis, i.e., focuses; M beams are respectively projected onto M regions of the corresponding first reflective region on the liquid crystal chip.

[0086] 7) such as Figure 4 As shown, beams of different wavelengths in each beam are transmitted parallel to each other and projected onto different pixel regions within their respective first reflection regions of the optical field modulator 11; through the liquid crystal graphic loading control system 12, a set phase holographic grating is loaded onto the pixel regions corresponding to different wavelengths in the M regions of the first beam deflection region of the optical field modulator 11, so that the reflected light of different wavelength beams produces a diffraction effect; as shown Figure 6The slight divergence of each light beam along the x' axis is converted into a parallel transmission state by changing the reflected diffracted light and the angle of the diffraction angle of the light in the x'z' plane by loading different phase diffraction gratings, so that the spot size of the multi-wavelength light beam along the x' axis direction remains unchanged during transmission. At this time, the light wave light field modulator 11 completes the first deflection of the first diffracted light beam and the second diffracted light beam, and defines the first deflection coordinate axis as x1', y1', z1', thereby establishing a three-dimensional coordinate system; the x1' axis is parallel to the x' axis, the y1' axis is parallel to the y' axis, and the z1' axis is parallel to the z' axis; that is, the light wave light field modulator 11 completes the first deflection of the light beam in the x1'z1' plane and the y1'z1' plane, and obtains a first deflected diffracted light beam according to the first diffracted light beam and a second deflected diffracted light beam according to the second diffracted light beam; the deflection angle of the first deflected diffracted light beam and the second deflected diffracted light beam in the y1'z1' plane is θ, and the included angle between the first deflected diffracted light beam and the second deflected diffracted light beam is 2θ; the light wave light field modulator 11 also completes the deflection of the first deflected diffracted light beam and the second deflected diffracted light beam in the x1'z1' plane, and the deflection angle is α1.

[0087] 8) The first deflected diffracted light beam and the second deflected diffracted light beam reflected and adjusted by the light wave light field modulator 11 reach the second long-focus cylindrical mirror 10 after the diffraction angle in the x1'z1' plane is reflected and adjusted; the second long-focus cylindrical mirror 10 converges the first deflected diffracted light beam and the second deflected diffracted light beam in the x'z' plane and projects them onto the first transmissive phase diffraction grating 8 and the second transmissive phase diffraction grating 9 respectively, and the multi-wavelength light beam in the first deflected diffracted light beam is inversely scattered by the second transmissive phase diffraction grating 9 to obtain a first inverse scattered light beam, and the multi-wavelength light beam in the second deflected diffracted light beam is inversely scattered by the first transmissive phase diffraction grating 8 to obtain a second inverse scattered light beam.

[0088] 9) The first inverse scattered light beam and the second inverse scattered light beam pass through the first transmissive phase diffraction grating 8 and the second transmissive phase diffraction grating 9 and then pass through the polarization beam splitting combination prism in reverse to reach the mirror 5, and the mirror 5 reflects the first inverse scattered light beam and the second inverse scattered light beam and then passes through the polarization beam splitting combination prism again to convert them into S deflection state to obtain a first inverse scattered deflected light beam and a second inverse scattered deflected light beam respectively, and the first inverse scattered deflected light beam and the second inverse scattered deflected light beam are parallel to each other; as Figure 3 shown, the spot size of the first inverse scattered light beam and the second inverse scattered light beam remains unchanged in the x axis direction and the y axis direction during transmission, and the first inverse scattered light beam and the second inverse scattered light beam are parallel light transmission.

[0089] 10) The first and second reverse dispersion beams pass through the second and first transmission phase diffraction gratings 9 and 8 again, respectively, and are dispersed. The dispersed beams are projected onto the light wave optical field modulator 11 by the second long-focus cylindrical lens 10. The parallel beams of different wavelengths in the same beam are projected onto different pixel regions of the light wave optical field modulator 11. The beams of the same wavelength in the first and second reverse dispersion beams are projected onto the same pixel region of the light wave optical field modulator 11. The liquid crystal pattern loading control system 12 loads the set phase holographic grating on the pixel region corresponding to the different wavelengths in the N regions of the first beam deflection region of the light wave optical field modulator 11, respectively, so that the reflected light beams of different wavelengths produce diffraction effects. By loading different phase diffraction gratings, the angle of the reflected diffracted light and the diffraction angle of the light in the x'z' plane are changed. Each beam is converted from a parallel light state to a slightly converging state along the x axis, which is the same as the state of the beam when it first enters the light wave optical field modulator 11 without being reflected for the first time. At this time, the light wave optical field modulator 11 completes the second deflection of the first and second reverse dispersion beams, and the second deflection coordinate axes are x2', y2', and z2', thereby establishing a three-dimensional coordinate system. The x2' axis is parallel to the x' axis, the y2' axis is parallel to the y' axis, and the z2' axis is parallel to the z' axis. At this time, the light wave optical field modulator 11 completes the second deflection of the beams in the x2'z2' plane and the y2'z2' plane. The first diffracted beam after the second deflection is obtained according to the first reverse dispersion beam, and the second diffracted beam after the second deflection is obtained according to the second reverse dispersion beam. The deflection angle of the first and second diffracted beams after the second deflection in the y2'z2' plane is θ, and the included angle between the first and second diffracted beams after the second deflection is 2θ. The light wave optical field modulator 11 also completes the deflection of the first and second diffracted beams after the second deflection in the x2'z2' plane, and the deflection angle is α1. The first and second diffracted beams after the second deflection that are reflected and adjusted by the light wave optical field modulator 11 reach the y2'z2' plane where the output port is located, and are transmitted to the corresponding output port.

[0090] 11) The first and second diffracted beams after the second deflection that are reflected and adjusted in the x2'z2' plane by the light wave optical field modulator 11 reach the first and second transmission phase diffraction gratings 8 and 9 after focusing by the second long-focus cylindrical lens 10, and then pass through the polarization combination prism in reverse. The first and second diffracted beams after the second deflection pass through the first long-focus cylindrical lens 3 and the short-focus cylindrical lens 2 in reverse and reach the output port of the one-dimensional fiber array 1. The M×N port wavelength selection switch reduces the energy loss of the entire M×N port wavelength selection switch by converting the incident light into light signals of the same polarization state.

[0091] The various embodiments described in this specification are presented for the purpose of illustrating the principles of the application and its best mode of operation. Each of the embodiments described in this specification are directed to a different embodiment of the application, and each of the embodiments can be combined with one another, unless otherwise indicated.

[0092] The principles and operation of the present application are explained further with reference to the accompanying drawings. While the present application has been described herein with reference to particular embodiments thereof, a latitude of modification, various changes and substitutions are intended in the foregoing disclosures, and in some instances some features of the present application will be employed without a corresponding use of other features. It is, therefore, to be understood that the appended descriptions and examples should be construed in an illustrative sense only and not limiting of the application.

Claims

1. A foldable M×N port wavelength selection switch, characterized in that, The foldable M×N port wavelength selection switch includes: A one-dimensional fiber array has M input ports and N output ports. The input ports and output ports are arranged in a one-dimensional array along the x-axis, with the M input ports in the center and the N output ports located on either side of the M input ports. The incident Gaussian beam emitted from each input port and the outgoing Gaussian beam entering the output port both propagate along the z-axis. A short-focal-length cylindrical mirror, wherein the incident Gaussian beam passes through the short-focal-length cylindrical mirror along the z-axis to form a short-focal-length Gaussian incident beam; The generatrices of the first long-focal cylindrical mirror and the short-focal cylindrical mirror are both located on the xz plane, and the z-axis passes through the generatrices of the first long-focal cylindrical mirror and the short-focal cylindrical mirror respectively; the short-focal Gaussian incident beam passes through the first long-focal cylindrical mirror to obtain a long-focal Gaussian incident beam. A polarizing beam splitter prism is placed perpendicular to the yz plane; A reflector is placed perpendicular to the yz plane, with its centerline parallel to the x-axis. The reflector is placed against a polarizing beam splitter prism and covers part of the polarizing beam splitter prism. The long-focal-length Gaussian incident beam passes through the polarizing beam splitter prism not covered by the reflector, forming a first beam and a second beam with the same polarization state and parallel to the z-axis. A first transmissive phase diffraction grating is placed perpendicular to the yz plane. The first beam passes through the first transmissive phase diffraction grating to obtain a first diffracted beam. A second transmissive phase diffraction grating is placed perpendicular to the yz plane, parallel to the first transmissive phase diffraction grating, and at a predetermined distance from the first transmissive phase diffraction grating; the second beam passes through the second transmissive phase diffraction grating to obtain a second diffracted beam; the second diffracted beam is parallel to the first diffracted beam; wherein, a three-dimensional coordinate system x'y'z' is established with the transmission path of the first diffracted beam as the z' axis, the x-axis parallel to the x' axis, and the y' axis perpendicular to the x'z' plane; The second long-focal cylindrical mirror is placed perpendicular to the y'z' plane. The midline of the first diffracted beam and the second diffracted beam is perpendicular to the central axis of the second long-focal cylindrical mirror, and the central axis of the second long-focal cylindrical mirror is perpendicular to the y'z' plane. The first diffracted beam and the second diffracted beam pass through the second long-focal cylindrical mirror. The first diffracted beam and the second diffracted beam are collimated and have dispersion compensated by the second long-focal cylindrical mirror to obtain the first long-focal beam and the second long-focal beam. An optical field modulator, corresponding to the second long-focal cylindrical lens, has M first beam deflection regions and N second beam deflection regions. Each first beam deflection region corresponds one-to-one with each input port and is centered. Each second beam deflection region corresponds one-to-one with each output port and is located on both sides of each first beam deflection region. The optical field modulator is used to reflect the first and second long-focal beams to obtain a first reflected beam and a second reflected beam, and to convert the divergence state of the first and second reflected beams on the x-axis into a parallel transmission state. The optical field modulator is placed perpendicular to the x'z' and y'z' planes and parallel to the x'y' plane; A liquid crystal graphic loading control system, connected to the optical wave field modulator, is used to load a phase grayscale image onto the optical wave field modulator according to the wavelengths of the first long focal beam and the second long focal beam; the optical wave field modulator is also used to change the angle of the diffraction angle of the first reflected beam and the second reflected beam in the x'z' plane according to the phase grayscale image.

2. The foldable M×N port wavelength selective switch according to claim 1, characterized in that, The polarization beam splitter prism includes: A polarizing beam splitter prism, wherein a reflector is placed in conjunction with the polarizing beam splitter prism, and the reflector covers a portion of the polarizing beam splitter prism; the long-focal Gaussian incident beam is split into a first initial beam in an S-polarization state and a second initial beam in a P-polarization state after passing through the polarizing beam splitter prism not covered by the reflector; An optical path conversion mirror, configured corresponding to the polarization beam splitter prism, is used to deflect the optical path propagation angle of the first initial beam in the S-polarization state to obtain the first beam in the S-polarization state. A half-wave plate, cemented together with the polarizing beam splitter prism, is used to change the P-polarization state of the second initial beam to the S-polarization state, forming a second beam with the S-polarization state.

3. The foldable M×N port wavelength selection switch according to claim 2, characterized in that, The optical path conversion mirror is a reflector or a right-angle prism.

4. The foldable M×N port wavelength selective switch according to claim 1, characterized in that, N is an even number, where along the x-axis, N / 2 output ports are located above M input ports, and N / 2 output ports are located below M input ports.

5. The foldable M×N port wavelength selective switch according to claim 1, characterized in that, The optical field modulator is a liquid crystal spatial light modulator.

6. The foldable M×N port wavelength selection switch according to claim 5, characterized in that, The liquid crystal spatial light modulator includes three liquid crystal chips.

7. The foldable M×N port wavelength selective switch according to claim 1, characterized in that, The short-focal-length cylindrical lens is a cylindrical lens with a focal length of 50mm or less.

8. The foldable M×N port wavelength selective switch according to claim 1, characterized in that, The first and second telephoto cylindrical lenses are cylindrical lenses with a focal length of 100mm-200mm.

9. The foldable M×N port wavelength selection switch according to claim 1, characterized in that, The one-dimensional fiber array is a one-dimensional single-mode fiber collimator array or a one-dimensional fiber array coupled with a microlens.

10. The foldable M×N port wavelength selective switch according to claim 1, characterized in that, The short-focal-length cylindrical lens, the first long-focal-length cylindrical lens, and the second long-focal-length cylindrical lens are transmission cylindrical lenses or reflection cylindrical lenses with embedded anti-reflective coating lenses.

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