Wavelength selective switch

Abstract

The embodiment of the application provides a wavelength selective switch, which comprises a dispersion element and a switching engine. The dispersion element can disperse multiplexed light input from an input port into a plurality of sub-beams in a dispersion plane and irradiate the sub-beams to the switching engine. The switching engine can deflect the plurality of sub-beams to form deflected sub-beams according to preset deflection angles in a switching plane, and output the deflected sub-beams from corresponding output ports. The deflection angles of one kind of wavelength beam and other wavelength beams are different, so that the one kind of wavelength beam can be separated and output from different output ports, and the scheduling and distribution of signal wavelengths are realized. The wavelength selective switch further comprises a first lens group. The first lens group can irradiate the multiplexed light to the dispersion element along a direction parallel to the dispersion plane in the switching plane, and irradiate the sub-beams dispersed by the dispersion element to the switching engine. The oblique incidence angle between the multiplexed light and the dispersion element is eliminated, the conical diffraction effect of the dispersion element is reduced, and the filter passband performance of the wavelength selective switch is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of communication, in particular to a wavelength selective switch. BACKGROUND

[0002] With the continuous development of optical communication technology, Wavelength Division Multiplexing (WDM for short) is a common optical layer networking technology at present, which can easily realize large-capacity transmission by multiplexing different wavelengths in one optical fiber. As a core optical switching device in the WDM network, the Reconfigurable Optical Add-Drop Multiplexer (ROADM for short) can select and configure any wavelength at any port. The Wavelength Selective Switch (WSS for short) is a core optoelectronic device of the Reconfigurable Optical Add-Drop Multiplexer, which can realize optical signal switching, attenuation or blocking of any wavelength or any combination of wavelengths at any port, and is one of the important devices in the current optical communication industry.

[0003] At present, the wavelength selective switch mainly includes an input port, a shaping system, an optical system, a dispersion element, a switching engine and an output system. The shaping system processes the light spot of the light beam entering from the input port, the optical system controls the light path and the light spot size of the light beam after the shaping system, the dispersion element can spatially separate or combine the light rays of different wavelengths in the light beam and irradiate them on the switching engine, the switching engine controls the angle deflection and attenuation of each wavelength of light rays, and then separates or combines the light rays of different wavelengths in different directions and outputs them through the corresponding output port. In a common wavelength selective switch, the optical system on the switching plane is a 4f optical system composed of lenses, and f is the focal length of the lens. For example, the 4f optical system includes a first lens and a second lens, the back focal plane of the first lens coincides with the front focal plane of the second lens, and the dispersion element is located on the coincident plane, that is, the dispersion element is located between the first lens and the second lens.

[0004] However, in the above wavelength selective switch, the incident light beam is obliquely incident on the dispersion element on the switching plane. Due to the conical diffraction effect of the dispersion element, the light spot of the light rays irradiated on the switching engine is in the shape of a crescent, which affects the filter passband performance of the wavelength selective switch. SUMMARY

[0005] The present application provides a wavelength selective switch which can reduce the conical diffraction effect of the dispersion element on the switching plane, thereby improving the filter passband performance of the wavelength selective switch.

[0006] The application provides a wavelength selective switch, comprising an input-output port group, the input-output port group comprising an input port and a plurality of output ports stacked in a first plane, the input port being configured to input a multiplexed light, the multiplexed light comprising a plurality of sub-beams of different wavelengths.

[0007] The wavelength selective switch further comprises a dispersion element and a switching engine, the dispersion element being configured to disperse the multiplexed light input from the input port into a plurality of sub-beams in a second plane, and irradiate the plurality of sub-beams onto different regions of the switching engine respectively, the first plane being orthogonal to the second plane. That is, in the second plane, the dispersion element can split the multiplexed light into a plurality of sub-beams and irradiate the plurality of sub-beams onto different regions of the switching engine, so that the switching engine can realize independent control of each wavelength channel.

[0008] The wavelength selective switch further comprises a first lens group, the dispersion element being located in the first lens group in the first plane, the first lens group being configured to irradiate the multiplexed light onto the dispersion element in the first plane along a direction parallel to the second plane, and the first lens group being further configured to irradiate the sub-beams emitted by the dispersion element onto the switching engine in the first plane. That is, in the first plane, after the multiplexed light input from the input port passes through the first lens group, the multiplexed light is irradiated onto the dispersion element along a direction parallel to the second plane, and the sub-beams emitted by the dispersion element pass through the first lens group and are irradiated onto the switching engine, so that the switching engine can realize independent control of each sub-beam.

[0009] The switching engine can realize independent control of the sub-beams of different wavelengths incident on the switching engine in the first plane, so that the transmission angle of each sub-beam in the first plane can be changed, and the sub-beams of different wavelengths can be controlled to be output from the corresponding output ports. Specifically, the switching engine can emit the plurality of sub-beams according to preset deflection angles in the first plane to form deflected sub-beams, the deflected sub-beams can pass through the first lens group and the dispersion element and be output from the output ports, so that different deflection angles of the sub-beams can cause the sub-beams to be irradiated onto different output ports. For example, if the deflection angle of a sub-beam of a certain wavelength is different from the deflection angles of the sub-beams of other wavelengths, the deflected sub-beam of the certain wavelength can be irradiated onto the corresponding output port, realizing separate output of the signal of the certain wavelength, and thus realizing scheduling and distribution of the signal wavelengths. Since the multiplexed light input from the input port in the first plane can pass through the first lens group and be irradiated onto the dispersion element along a direction parallel to the second plane, the oblique incidence angle between the multiplexed light and the dispersion element in the switching plane (the first plane) is reduced or eliminated, the difference in the incidence angle of each sub-beam in the multiplexed light on the dispersion element is reduced or avoided, the conical diffraction effect of the dispersion element is significantly reduced, the spot morphology is improved, and thus the filter passband performance of the wavelength selective switch is significantly improved.

[0010] In addition, the difference in the incident angle of each deflected beam on the dispersion element when the deflected beams return and pass through the dispersion element is reduced, the insertion loss of the wavelength selective switch is reduced, and the performance of the wavelength selective switch is further improved.

[0011] In a possible implementation, the first lens group includes a first lens, a second lens, a third lens, and a fourth lens, and the dispersion element is located between the second lens and the third lens.

[0012] The first lens is configured to irradiate the multiplexed light onto the second lens in the first plane.

[0013] The second lens is configured to irradiate the multiplexed light passing through the first lens to the dispersion element in a direction parallel to the second plane in the first plane.

[0014] The third lens is configured to irradiate the sub-beams dispersed by the dispersion element to the fourth lens in the first plane.

[0015] The fourth lens is configured to irradiate the sub-beams passing through the third lens to the switching engine in a direction parallel to the second plane in the first plane. That is, in the first plane, the multiplexed light input from the input port is irradiated to the second lens after being refracted by the first lens, the second lens refracts the multiplexed light passing through the first lens again, so that the multiplexed light is irradiated to the dispersion element in a direction parallel to the second plane, thereby reducing the difference in the incident angle of each sub-beam in the multiplexed light on the dispersion element, and achieving the purpose of reducing the conical diffraction effect of the dispersion element.

[0016] The sub-beams dispersed by the dispersion element are irradiated to the fourth lens after being refracted by the third lens, and the fourth lens refracts them again, so that the sub-beams are irradiated to the switching engine in a direction parallel to the second plane, thereby facilitating the switching engine to deflect the sub-beams to form deflected beams and ensuring the realization of the individual control of the sub-beams by the switching engine.

[0017] In a possible implementation, the back focal surface of the first lens coincides with the front focal surface of the second lens, and the back focal surface of the second lens coincides with the dispersion element.

[0018] The front focal surface of the third lens coincides with the dispersion element, and the back focal surface of the third lens coincides with the front focal surface of the fourth lens.

[0019] In a possible implementation, the focal length of the first lens, the focal length of the second lens, the focal length of the third lens, and the focal length of the fourth lens are all equal, such as f, and the first lens group is an 8f optical system, which can play a relay role, that is, the light beam passing through the first lens group maintains the original optical characteristics (such as the size of the light beam, the direction of propagation, etc.), so that the spot on the front focal plane of the first lens can be the same size as the spot on the rear focal plane of the fourth lens, and the size of the spot is regulated through the first lens group, which helps to improve the filter passband performance of the wavelength selection switch.

[0020] In a possible implementation, the dispersion element is located between the second lens and the third lens, so that the multiplexed light is irradiated to the dispersion element in a direction parallel to the second plane, the conical diffraction effect is reduced, and the appearance of the spot on the switching engine is improved.

[0021] In a possible implementation, the switching lens group is further configured to expand the multiplexed light in the first plane and irradiate the multiplexed light to the first lens group in a direction parallel to the second plane. That is, in the first plane, the multiplexed light input from the input port passes through the switching lens group, the switching lens group can expand the multiplexed light, and the multiplexed light is irradiated to the first lens group in a direction parallel to the second plane. The switching lens group can magnify the spot in the first plane, increase the area of the spot, and regulate the spot.

[0022] The switching lens group is further configured to switch the deflected sub-beams regulated by the switching engine to different output ports, that is, in the first plane, the switching lens group can refract the deflected sub-beams after the first lens group and the dispersion element to the corresponding output ports to output, thereby scheduling and distributing the signal wavelengths.

[0023] In a possible implementation, the switching lens group includes a fifth lens, and the curved surface of the fifth lens is located in the first plane, that is, in the first plane, the fifth lens refracts the light beam passing therethrough, thereby expanding the multiplexed light input from the input port, and refracting and deflecting the deflected sub-beams after the first lens group and the dispersion element to the corresponding output ports to implement scheduling and distribution of the signal wavelengths.

[0024] In a possible implementation, the second lens group is further included, and the dispersion element is located in the second lens group in the second plane, and the second lens group is configured to expand the multiplexed light in the second plane and irradiate the multiplexed light to the dispersion element.

[0025] The second lens group is further configured to irradiate the sub-beams dispersed by the dispersion element onto the switching engine in the second plane, that is, the plurality of sub-beams emitted by the dispersion element can be respectively converged onto different regions of the switching engine after passing through the second lens group, and the second lens group can realize the regulation of the light spot.

[0026] In a possible implementation, the second lens group includes a sixth lens and a seventh lens.

[0027] The sixth lens is configured to irradiate the multiplexed light to the dispersion element after expanding the multiplexed light in the second plane.

[0028] The seventh lens is configured to respectively converge the sub-beams dispersed by the dispersion element in the second plane, so that the sub-beams are respectively irradiated on different regions of the switching engine. That is, in the second plane, the multiplexed light passes through the sixth lens, the sixth lens expands the multiplexed light, and then the multiplexed light is irradiated onto the dispersion element. The seventh lens can respectively converge the sub-beams dispersed by the dispersion element, so that the plurality of sub-beams are respectively irradiated on different regions of the switching engine, so that the switching engine can realize independent processing of the wavelength beams and realize scheduling and distribution of the signal wavelength.

[0029] In a possible implementation, the back focal plane of the sixth lens coincides with the dispersion element, and the front focal plane of the seventh lens coincides with the dispersion element.

[0030] In a possible implementation, the focal length of the sixth lens and the focal length of the seventh lens are equal, for example, both are f, so that the second lens group is a 4f optical system, the second lens group can play a relay role, realizes the regulation of the light spot, and makes the light spot size of the front focal plane of the sixth lens consistent with the light spot size of the back focal plane of the seventh lens.

[0031] In a possible implementation, a third lens group is further included, and the third lens group is configured to irradiate the multiplexed light to the second lens group in the second plane. The third lens group can regulate the optical path and the light spot size of the multiplexed light,

[0032] In a possible implementation, the third lens group includes an eighth lens and a ninth lens, and the eighth lens is configured to irradiate the multiplexed light to the ninth lens after expanding the multiplexed light in the second plane.

[0033] The ninth lens is configured to converge the multiplexed light passing through the eighth lens and irradiate the multiplexed light to the second lens group in the second plane, so that the multiplexed light is expanded after passing through the eighth lens and then converged after passing through the ninth lens. After passing through the third lens group, the control of the light spot is realized, and the phenomenon of increasing light spot size with the transmission of the multiplexed light is reduced.

[0034] In a possible implementation, the back focal surface of the eighth lens coincides with the front focal surface of the ninth lens. The focal length of the eighth lens can be equal to the focal length of the ninth lens, such as both being f, so that the third lens group is a 4f optical system, and the third lens group also functions as a relay to regulate the light path and the light spot, so that the light spot at the front focal surface of the eighth lens is consistent with the light spot at the back focal surface of the ninth lens.

[0035] In a possible implementation, the number of input and output port groups is multiple, and the multiple input and output port groups are stacked in the first plane. In this way, the integration of multiple light signals can be realized, so that multiple beams of multiplexed light can be simultaneously input into the wavelength selective switch, thereby helping to reduce the cost of the entire transmission system.

[0036] In a possible implementation, the dispersion element includes a grating or an echelle. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 A schematic diagram of a structure of an all-optical network system provided by an embodiment of the present application;

[0038] Figure 2 A schematic diagram of a structure of an optical switching node provided by an embodiment of the present application;

[0039] Figure 3 A schematic diagram of a structure of a wavelength selective switch provided by an embodiment of the present application;

[0040] Figure 4 A schematic diagram of a light path in a switching plane of a wavelength selective switch in the related art;

[0041] Figure 5 A schematic diagram of a light spot formed on a switching engine of a wavelength selective switch in the related art;

[0042] Figure 6 A schematic diagram of a light path in a second plane of a wavelength selective switch provided by an embodiment of the present application;

[0043] Figure 7 A schematic diagram of a light path in a first plane of a wavelength selective switch provided by an embodiment of the present application;

[0044] Figure 8 A schematic diagram of a light spot formed on a switching engine of a wavelength selective switch provided by an embodiment of the present application;

[0045] Figure 9 A schematic diagram of a light path in a first plane of another wavelength selective switch provided by an embodiment of the present application;

[0046] Figure 10 A schematic diagram of a light path of channel switching of a wavelength selective switch provided by an embodiment of the present application;

[0047] Figure 11 Another wavelength selective switch provided by the embodiment of the present application is shown in the light path schematic diagram in the second plane.

[0048] Explanation of reference signs:

[0049] 100-wavelength selective switch; 10-input / output port group; 11-input port;

[0050] 12-output port; 20-dispersion element; 30-switching engine;

[0051] 40-first lens group; 41-first lens; 42-second lens;

[0052] 43-third lens; 44-fourth lens; 50-switching lens group;

[0053] 51-fifth lens; 60-second lens group; 61-sixth lens;

[0054] 62-seventh lens; 70-third lens group; 71-eighth lens;

[0055] 72-ninth lens. DETAILED DESCRIPTION

[0056] The terms used in the embodiment part of the present application are only used for explaining the specific embodiments of the present application, and are not intended to limit the present application.

[0057] The embodiment of the present application provides a wavelength selective switch, which can be applied in optical fiber communication technology, and is especially suitable for trunk or metropolitan area network system of long distance optical fiber communication, and is used for realizing scheduling of signal wavelength, i.e. realizing uploading and downloading of signals, so that wavelength allocation can be realized remotely and dynamically, work efficiency is improved, and reaction time to user demand is shortened.

[0058] Specifically, the wavelength selective switch can be applied in an all optical network (AON for short) system, wherein the all optical network system refers to that a signal always exists in the form of an optical signal in the transmission, switching and amplification process in the network, and is not processed by an electrical signal, and only performs electrical-optical and optical-electrical conversion when entering and exiting the network. Since the AON is a direct optical fiber communication network constituted by optical fibers as optical propagation media, is not affected by the response speed of electronic devices in the traditional network, and can effectively reduce network delay and system power consumption, the AON is widely applied. The AON based on dense wavelength division multiplexing (DWDM for short) technology can realize high-speed and large-capacity information transmission and processing, and is one of the main communication development trends.

[0059] In the AON, optical switching nodes are used to replace the electrical nodes in the traditional network. In order to meet the dynamic demand of network traffic, the optical switching node needs to have the ability to allocate resources on demand. In addition, due to the increase of network traffic, the optical switching node needs to have multi-dimensional uplink and downlink ports to fully utilize the network capacity of the wavelength division multiplexing technology and perform multi-dimensional service scheduling. The optical switching node can be composed of a reconfigurable optical add-drop multiplexer (ROADM). The ROADM is a device that can add, block, pass through, or redirect different wavelength optical signals in a fiber communication network. Through remote reconfiguration, the wavelength of the uplink or downlink service can be dynamically configured according to the demand, and the flexible scheduling of the service can be realized. The wavelength selective switch has the function of selecting and outputting a specific wavelength from the input wavelength. After the optical signals of any input port and any wavelength are demultiplexed, they can be non-blocked and scheduled to any output port. The wavelength selective switch can be applied to the ROADM and can be used as a key module to realize a multi-dimensional, flexible ROADM. In other words, the wavelength selective switch can realize the switching, attenuation, or blocking of optical signals of any wavelength or any combination of wavelengths at any port.

[0060] Of course, in some other examples, the wavelength selective switch can also be applied to other communication network devices or systems, which are not limited in the embodiments of the present application.

[0061] The application scenario of the wavelength selective switch is described below by taking the wavelength selective switch applied to an all-optical network system.

[0062] Figure 1 A schematic diagram of an all-optical network system is provided for the embodiments of the present application, Figure 2 A schematic diagram of an optical switching node is provided for the embodiments of the present application.

[0063] Specifically, referring to Figure 1As shown in the figure, the all-optical network system can include a backbone network ring 300 and an access network ring 400, wherein the backbone network ring 300 can include a plurality of optical switching nodes 301, specifically, the optical switching nodes 301 can be ROADMs, which can dynamically configure uplink or downlink service wavelengths according to requirements, realize flexible scheduling of services, and the backbone network ring 300 further includes an uplink user terminal 302. The access network ring 400 can include a plurality of downlink user terminals 401, and the access network ring 400 performs uplink and downlink service with the backbone network ring 300 through the optical switching nodes 301 to realize communication between the uplink user terminal 302 and the downlink user terminal 401, wherein the uplink and downlink service refers to optical signal transmission between the access network ring 400 and the backbone network ring 300. The downlink user terminal 401 can be a connection device that can provide a connection to a user 402, for example, can be a voice and / or data connection device, or can be a computer device such as a laptop computer, a desktop computer, or an independent device such as a personal digital assistant (PDA), which is not limited in the embodiment of the present application.

[0064] Referring to Figure 2 As shown in the figure, the optical switching node as a ROADM can include a plurality of wavelength selective switches 100, the wavelength selective switch 100 can realize arbitrary cross-connection of optical signals between the access network ring 400 and the backbone network ring 300, and can dynamically adjust the uplink and downlink of each switching node in the all-optical network, thereby realizing wavelength allocation between the optical switching nodes in the all-optical network.

[0065] It should be understood that the optical switching node can further include other devices, for example, a fiber amplifier, a waveguide grating, etc., which are not limited in the embodiment of the present application.

[0066] Figure 3 A schematic diagram of a wavelength selective switch provided in the embodiment of the present application.

[0067] Referring to Figure 3 As shown in the figure, the wavelength selective switch 100 can include an input port 11, an output port 12 and a wave separation device 101, wherein the input port 11 can be composed of an optical fiber, and can supply an optical beam into the wavelength selective switch 100. Specifically, the input port 11 is used for inputting multiplexed light, and the multiplexed light can contain a plurality of sub-beams of different wavelengths, in other words, the multiplexed light can include sub-beams of wavelengths λ1, λ2, λ3, λ4, λ5…λm, m≥2. The multiplexed light can enter the wavelength selective switch 100 through the input port 11.

[0068] The multiplexed light can be formed by multiplexing sub-beams of different wavelengths together through DWDM technology. The wavelengths of the sub-beams in the multiplexed light can be commonly used wavelengths in a DWDM communication system, and the specific wavelength values can be selected and set according to requirements.

[0069] The wavelength separation device 101 can separate the multiplexed light input from the input port 11, separate at least one wavelength of sub-beam in the multiplexed light from other wavelengths of sub-beam in the multiplexed light, and output the separated sub-beam from the corresponding output port 12 to the outside of the wavelength selective switch 100, so as to separate the sub-beam of the wavelength and realize scheduling of the signal wavelength, and remotely and dynamically realize allocation of the wavelength. It should be noted that the separated sub-beam can include a sub-beam of a required wavelength, or the separated sub-beam can include sub-beams of two or more than two required wavelengths. The specific separation mode can be selected and set according to the requirements of the communication system.

[0070] For example, taking the multiplexed light including sub-beams of five wavelengths λ1, λ2, λ3, λ4 and λ5 as an example, the wavelength separation device 101 separates the multiplexed light, and separates the sub-beams of three wavelengths λ1, λ3 and λ5 (see FIG. 1B) and outputs them from the corresponding output ports 12, respectively. The sub-beams of wavelengths λ2 and λ4 can be combined together to form a light beam after separation, and output from the corresponding output port 12. Figure 3

[0071] It should be understood that the number of output ports 12 can be multiple to realize output of the separated light beams. Specifically, the number of output ports 12 can be consistent with the number of separated light beams of the wavelength separation device 101, so as to meet the output requirements of the separated light beams.

[0072] The input port 11 and the output port 12 can be arranged in a direction in the embodiment of the present application, and the direction of the arrangement of the input port 11 and the output port 12 is the x direction (see FIG. 1B), the propagation direction of the multiplexed light input from the input port 11 perpendicular to the x direction is the z direction, and the plane formed by the x direction and the z direction is the first plane, that is, the x-z plane. The direction perpendicular to the first plane is the y direction, and the plane formed by the y direction and the z direction is the second plane, that is, the y-z plane, and the second plane is orthogonal to the first plane. Figure 7

[0073] ​​The first plane can be used as the switching plane of the wavelength selection switch 100, and the second plane can be used as the dispersion plane of the wavelength selection switch 100. Within the dispersion plane, the multiplexed light entering from the input port 11 is dispersed into multiple sub-beams of different wavelengths, thereby enabling individual processing of each wavelength signal. Within the switching plane, the sub-beams of different wavelengths are adjusted and controlled, for example, by deflecting the sub-beams of different wavelengths by a preset angle, so that they are output from the corresponding output port 12.

[0074] The wavelength division multiplexing (WDM) device can include a dispersion unit and a switching engine. The dispersion unit is used to separate the multiplexed light. The dispersion unit can be an optical element such as a grating that can perform beam splitting. For example, taking a grating as an example, in the dispersion plane, the grating can disperse the multiplexed light passing through it into multiple sub-beams, each with a different wavelength. The dispersion element disperses the multiplexed light into multiple sub-beams and illuminates them onto different areas of the switching engine, forming light spots on the switching engine. In the switching plane, the switching engine can independently control the sub-beams of different wavelengths to achieve the separation and output of signals of a specific wavelength.

[0075] Specifically, the switching engine can deflect multiple sub-beams, causing them to deflect at preset angles. The switching engine can also adjust different areas, enabling independent control of sub-beams of different wavelengths. This allows for control of the deflection angle of each sub-beam, ensuring that different deflection angles result in different wavelengths of deflected sub-beams being output from their respective output ports, thus achieving channel switching.

[0076] Figure 4 This is a schematic diagram of the optical path of a wavelength selective switch in the switching plane in related technologies. Figure 5 This is a schematic diagram of the light spot formed on the switching engine of a wavelength selective switch in related technologies.

[0077] Specifically, the wavelength selection switch also includes an image rotation system 4, with the grating 3 located within the image rotation system 4, on the switching plane ( Figure 4 In the xz plane, the multiplexed light input from the input port 1a passes through the image transfer system 4 and then shines on the switching engine 5. The image transfer system 4 can adjust and control the size of the light path and the light spot.

[0078] The image-spinning system 4 can be composed of lenses. Specifically, common image-spinning systems 4 are often 4f optical systems composed of lenses, where f is the focal length of the lens. For example, see... Figure 4As shown, the relay system 4 can include a first lens 4a and a second lens 4b, the back focal surface of the first lens 4a and the front focal surface of the second lens 4b coincide, the focal length of the first lens 4a and the second lens 4b are both f, the switching engine 5 can be located on the back focal surface of the second lens 4b, and the distance between the front focal surface of the first lens 4a and the back focal surface of the second lens 4b is 4f.

[0079] The grating 3 can be located in the middle of the first lens 4a and the second lens 4b, that is, the grating 3 is located in the middle of the entire 4f optical system. The curved surface of the first lens 4a is located in the switching plane, and the curved surface of the second lens 4b is also located in the switching plane, that is, in the switching plane (x-z plane), the light beams passing through the first lens 4a and the second lens 4b along the z direction are refracted by the first lens 4a and the second lens 4b.

[0080] In other words, in the switching plane, the multiplexed light input from the input port 1a passes through the first lens 4a and is refracted by the first lens 4a to the grating, and after passing through the grating 3, it is irradiated to the second lens 4b and is refracted by the second lens 4b to the switching engine 5.

[0081] The grating 3 is located in the middle of the 4f optical system, as shown in Figure 4 As shown, in the switching plane, when the multiplexed light refracted by the first lens 4a converges and irradiates to the grating 3, an oblique incident angle (the incident angle is 0°-90°, in other words, there is an angle between the transmission direction of the multiplexed light and the dispersion plane) is formed between the multiplexed light and the grating 3, and the conical diffraction phenomenon of the grating 3 is easy to occur. Specifically, the multiplexed light is incident at an oblique angle, and the incident angles of the sub-beams in the multiplexed light relative to the grating 3 are different, and correspondingly, the exit angles of the sub-beams after diffraction by the grating 3 are also different, which is the conical diffraction phenomenon. Due to the conical diffraction phenomenon, after the sub-beams irradiate to the switching engine 5, a crescent-shaped spot 5a as shown in Figure 5 is formed on the switching engine 5. When channel switching is realized by the switching engine, part of the sub-beams is missing, which affects the deflection accuracy of the sub-beams, thereby affecting the filter passband performance of the wavelength selective switch.

[0082] Moreover, when the sub-beams are deflected by the switching engine 5 and return along the original path, the incident angle between the sub-beams and the grating 3 can further increase, and the conical diffraction phenomenon can occur again, and the spot can be further distorted, making it difficult for the sub-beam spot passing through the grating 3 to recover to a standard Gaussian light, affecting the insertion loss of the wavelength selective switch, and further reducing the performance of the wavelength selective switch.

[0083] Based on this, the wavelength selective switch provided in the embodiments of the present application can greatly reduce the conical diffraction phenomenon of the grating and the like dispersion element, improve the filter passband performance of the wavelength selective switch, and reduce the insertion loss of the wavelength selective switch.

[0084] The optical path architecture of the wavelength selective switch in the switching plane and the dispersion plane is described in detail below with reference to the accompanying drawings.

[0085] Figure 6 An optical path schematic diagram of a wavelength selective switch provided in the embodiments of the present application in the second plane is shown.

[0086] In the embodiments of the present application, a bundle of multiplexed light including a plurality of sub-beams of different wavelengths is taken as an example for description. The first plane is the x-z plane, and the first plane can be the switching plane of the wavelength selective switch. The second plane is the y-z plane, and the second plane can be the dispersion plane of the wavelength selective switch 100.

[0087] The wavelength selective switch includes a dispersion element 20 and a switching engine 30. The dispersion element 20 can be a grating, or the dispersion element 20 can also be a prism grating, which can include a prism and a grating. Of course, in some examples, the dispersion element 20 can also be other optical elements capable of acting as a light splitter.

[0088] The switching engine 30 can be a liquid crystal on silicon (LCOS), or the switching engine 30 can also be a micro-electro-mechanical system (MEMS), or the switching engine 30 can also be a digital light processing (DLP), or the switching engine 30 can also be a liquid crystal switching chip or other chip capable of realizing optical path switching.

[0089] Specifically, the dispersion element 20 can be located on the optical path between the input port 11 and the switching engine 30, and the dispersion plane of the dispersion element 20 can be located in the second plane. Referring to Figure 6 In other words, in the y-z plane, the multiplexed light input from the input port 11 along the z direction passes through the dispersion element 20, the dispersion element 20 can act as a light splitter on the multiplexed light, so that the different wavelength beams in the incident multiplexed light are dispersed in space at different angles, and the plurality of sub-beams are respectively irradiated onto different regions of the switching engine 30.

[0090] Figure 7 An optical path schematic diagram of a wavelength selective switch provided in the embodiments of the present application in the first plane is shown.

[0091] Referring to Figure 7 As shown in FIG. 1, the wavelength selective switch 100 further comprises a first lens group 40, in the first plane, the dispersion element 20 is located in the first lens group 40, in the first plane (x-z plane), the first lens group 40 can irradiate the multiplexed light onto the dispersion element 20 along a direction parallel to the second plane (y-z plane), that is, the multiplexed light input from the input port 11 can be irradiated onto the dispersion element 20 along a direction parallel to the second plane after passing through one or more lenses of the first lens group 40. For example, the first lens group 40 can comprise a plurality of lenses, in the first plane, the multiplexed light input from the input port 11 can be irradiated onto the dispersion element 20 along a direction parallel to the second plane after passing through one or more lenses of the first lens group 40.

[0092] In the first plane, the first lens group 40 can also irradiate the sub-beams emitted by the dispersion element 20 onto the switching engine 30 to enable the switching engine 30 to achieve individual control of the sub-beams.

[0093] Figure 8 A schematic diagram of a light spot formed on the switching engine in a wavelength selective switch according to an embodiment of the present application.

[0094] Specifically, the plurality of sub-beams dispersed by the dispersion element 20 are irradiated onto different regions of the switching engine 30 by the first lens group 40 and form light spots on the switching engine 30 (see FIG. 1). Figure 8 As shown in FIG. 1, the switching engine 30 can achieve individual processing of the sub-beams of different wavelengths on different regions, that is, the sub-beams of different wavelengths can be individually controlled, wherein the control of the sub-beams can include optical signal switching, optical signal attenuation, and optical signal blocking, etc.

[0095] In the first plane (x-z), the switching engine 30 can change the transmission angles of the sub-beams corresponding to different regions, so that the plurality of sub-beams are deflected at preset angles respectively and form deflected sub-beams, which return along the original path, irradiate onto the output port 12 after passing through the first lens group 40 and the dispersion element 20. In this way, the deflected sub-beams corresponding to different output ports can be formed by making the deflection angles of the sub-beams different, for example, by making the deflection angle of the sub-beams of one wavelength different from those of other sub-beams, the deflected sub-beams of the wavelength can be output from the corresponding output port 12, thereby achieving separate output of the sub-beams of the wavelength and further achieving scheduling and distribution of the signal wavelengths.

[0096] As the multiplexed light inputted from the input port 11 can be irradiated onto the dispersive element 20 along a direction parallel to the second plane through the first lens group 40, the inclination angle between the multiplexed light and the dispersive element 20 in the switching plane (the first plane) can be reduced or eliminated, the difference of the incidence angle of each sub-beam of the multiplexed light on the dispersive element 20 can be reduced or avoided, the conical diffraction effect of the dispersive element 20 can be significantly reduced, the appearance of the spot can be improved, the loss of the sub-beam during the channel switching can be reduced or avoided, and the filter passband performance of the wavelength selective switch 100 can be significantly improved. Referring to Figure 8 As shown in FIG. 1, the spot on the switching engine 30 can be a standard Gaussian spot. Figure 8 As shown in FIG. 1, the spot on the switching engine 30 can be a standard Gaussian spot.

[0097] In addition, it is also helpful to reduce the difference of the incidence angle of each deflected sub-beam on the dispersive element 20 when the deflected sub-beam returns and passes through the dispersive element 20, to reduce the insertion loss of the wavelength selective switch 100, and to further improve the performance of the wavelength selective switch 100.

[0098] As shown in FIG. 1, the input port 11 and the output port 12 are arranged in a stack in the x direction, that is, the input port 11 and the output port 12 are arranged in an array in the x-z plane (the first plane), and the input port 11 and the output port 12 can form an input-output port group 10, that is, one input-output port group 10 includes one input port 11 and multiple output ports 12. Figure 7 The wavelength selective switch 100 can include multiple input-output port groups 10, and the multiple input-output port groups 10 can be arranged in a stack in the first plane. The input-output port groups 10 can also be arranged in an array, and each array can include one or more input-output port groups 10. In this way, the integration of multiple optical signals can be realized, and multiple multiplexed light beams can be simultaneously inputted into the wavelength selective switch, thereby helping to reduce the cost of the entire transmission system.

[0099] The input-output port group 10 can include a fiber array, and the fiber array can include multiple optical fibers, which are respectively used as the input port 11 and the output port 12.

[0100] The input-output port group 10 can further include other optical devices that are helpful for optical signal transmission, for example, a collimating lens array and the like.

[0101] As shown in FIG. 1, the input port 11 and the output port 12 in each input-output port group 10 can be arranged in a stack in multiple ways, for example, multiple output ports 12 can be located on one side of the input port 11, or part of the output ports 12 can be located on one side of the input port 11, and part of the output ports 12 can be located on the other side of the input port 11.

[0102] ​

[0103] In each input-output port group 10, the input ports 11 and the output ports 12, and the output ports 12 and the output ports 12 can be arranged at intervals, and the interval distances can be equal.

[0104] Continuing to refer to Figure 7 As shown, specifically, the first lens group 40 can include a first lens 41, a second lens 42, a third lens 43, and a fourth lens 44, and the dispersion element 20 can be located on the optical path between the second lens 42 and the third lens 43. The first lens 41, the second lens 42, the third lens 43, and the fourth lens 44 can be cylindrical lenses, and of course in some other examples, the first lens 41, the second lens 42, the third lens 43, and the fourth lens 44 can also be other shapes of lenses.

[0105] With the first lens 41, the second lens 42, the third lens 43, and the fourth lens 44 being cylindrical lenses, the curved surface of the first lens 41 is located in the first plane, in other words, for a light beam passing through the first lens 41 along the z direction, the cross section of the first lens 41 in the y-z plane is a plane, and the cross section in the x-z plane is a curved surface. In the x-z plane (the first plane), the first lens 41 will refract the light beam when the light beam passes through the first lens 41, and the propagation direction of the light beam changes, while in the y-z plane (the second plane), the propagation direction of the light beam remains unchanged when the light beam passes through the first lens 41.

[0106] Correspondingly, the curved surfaces of the second lens 42, the third lens 43, and the fourth lens 44 are also located in the first plane, and in the x-z plane (the first plane), the propagation direction of the light beam changes when the light beam passes through the second lens 42, the third lens 43, and the fourth lens 44. In the y-z plane (the second plane), the propagation direction of the light beam remains unchanged when the light beam passes through the second lens 42, the third lens 43, and the fourth lens 44.

[0107] Specifically, in the first plane (the x-z plane), the multiplexed light input from the input port 11 is refracted by the first lens 41 and irradiated onto the second lens 42. The second lens 42 refracts the multiplexed light again, so that the multiplexed light is irradiated to the dispersion element 20 along a direction parallel to the second plane, thereby reducing the difference in the incidence angle of each sub-beam in the multiplexed light on the dispersion element 20, and achieving the purpose of eliminating the conical diffraction effect of the dispersion element 20.

[0108] The sub-beams dispersed by the dispersion element 20 are refracted by the third lens 43 and then irradiate the fourth lens 44, and the fourth lens 44 refracts the sub-beams again, so that the sub-beams irradiate the switching engine 30 in a direction parallel to the second plane, thereby facilitating the switching engine 30 to deflect the sub-beams to form deflected sub-beams, and ensuring that the switching engine 30 controls the sub-beams.

[0109] It should be understood that when the input-output port group 10 is multiple, the multiple input-output port groups 10 can correspond to one first lens group 40 and one dispersion element 20, that is, the multiple beams of multiplexed light entering the wavelength selective switch 100 from the input ports 11 of the multiple input-output port groups 10 irradiate different regions of the switching engine 30 after passing through the same first lens group 40 and dispersion element 20.

[0110] Figure 9 Another wavelength selective switch provided by the embodiment of the present application is shown in the optical path diagram in the first plane.

[0111] Referring to Figure 9 As shown in the figure, the back focal surface of the first lens 41 can coincide with the front focal surface of the second lens 42, the back focal surface of the second lens 42 can coincide with the dispersion element 20, the front focal surface of the third lens 43 can coincide with the dispersion element 20, and the back focal surface of the third lens 43 can coincide with the front focal surface of the fourth lens 44.

[0112] In the first lens group 40, the distance between the front focal surface of the first lens 41 and the back focal surface of the fourth lens 44 is f1+f1+f2+f2+f3+f3+f4+f4, where f1 is the focal length of the first lens 41, f2 is the focal length of the second lens 42, f3 is the focal length of the third lens 43, and f4 is the focal length of the fourth lens 44.

[0113] The focal length f1 of the first lens 41, the focal length f2 of the second lens 42, the focal length f3 of the third lens 43, and the focal length f4 of the fourth lens 44 can all be equal, such as f, and the first lens group 40 is an 8f optical system. The first lens group 40 can play a relay role, specifically, the relay role means that the light beams passing through the lens group maintain the original optical characteristics (such as the size of the light beams, the direction of propagation, etc.), and the size of the light spot at the front focal surface of the first lens 41 is consistent with the size of the light spot at the back focal surface of the fourth lens 44. In this way, the first lens group 40 can realize the regulation of the size of the light spot, which helps to improve the filter passband performance of the wavelength selective switch 100.

[0114] Of course, in some other examples, the focal length f1 of the first lens 41, the focal length f2 of the second lens 42, the focal length f3 of the third lens 43 and the focal length f4 of the fourth lens 44 can also all be unequal. Alternatively, the focal lengths of some of the first lens 41, the second lens 42, the third lens 43 and the fourth lens 44 can be equal, and the focal lengths of some of the first lens 41, the second lens 42, the third lens 43 and the fourth lens 44 can be unequal.

[0115] The dispersion element 20 can be located in the middle of the second lens 42 and the third lens 43, so as to make the multiplexed light irradiate to the dispersion element 20 in a direction parallel to the second plane, reduce the conical diffraction effect, thereby improving the spot morphology on the switching engine 30 and improving the filter passband performance of the wavelength selective switch 100.

[0116] It should be noted that in the embodiments of the present application, the lens can be a single lens element, that is, the first lens group 40 can include four lens elements to meet the optical path requirements of the first lens group 40. Alternatively, the lens can be composed of two or more lens elements, which can be equivalent to one lens in the optical path to achieve its optical path effect. For example, taking the first lens 41 as an example, the first lens 41 can be equivalent to two lens elements, which can achieve the optical path effect of the first lens 41. Alternatively, two lenses can share one or more lens elements, which can achieve their optical path effects respectively. For example, the first lens 41 can be equivalent to two lens elements, such as the first lens 41 element and the second lens 42 element. The second lens 42 can also be equivalent to two lens elements, and the first lens 41 and the second lens 42 can share one lens element, such as the second lens 42, which can be equivalent to the second lens 42 element and the third lens 43 element, which can achieve the optical path effect of the first lens 41 and the second lens 42.

[0117] Figure 10 A wavelength selective switch channel switching optical path schematic diagram provided by the embodiments of the present application.

[0118] Referring to Figure 10 As shown, the wavelength selective switch 100 can further include a switching lens group 50, which can be located on the optical path between the input port 11 and the first lens group 40. In the first plane (x-z plane), the switching lens group 50 can perform beam expansion processing on the multiplexed light, and make the beam expansion processed multiplexed light irradiate to the first lens group 40 along a direction parallel to the second plane.

[0119] In other words, within the first plane, the multiplexed light input from input port 11 passes through the switching lens group 50. The switching lens group 50 can expand the multiplexed light, causing it to illuminate the first lens group 40 along a direction parallel to the second plane, specifically onto the first lens 41 of the first lens group 40. The switching lens group 50 can magnify the light spot within the first plane, increasing the spot area and enabling control over the light spot, thus improving the performance of the wavelength selective switch.

[0120] The multiplexed light sequentially passes through the first lens 41 and the second lens 42 to illuminate the dispersive element 20. The dispersive element 20 disperses the multiplexed light into multiple sub-beams in the second plane. These sub-beams sequentially pass through the third lens 43 and the fourth lens 44 before illuminating the switching engine 30. The switching engine 30 can deflect the multiple sub-beams at a preset angle in the first plane to form a deflector beam. The deflector beam returns along its original path, sequentially passing through the fourth lens 44, the third lens 43, the dispersive element 20, the second lens 42, and the first lens 41 before illuminating the switching lens group 50. The switching lens group 50 can also refract the aforementioned deflector beam to the corresponding output port 12, thereby realizing the scheduling and distribution of signal wavelengths.

[0121] Specifically, the switching lens may include a fifth lens 51, which may also be a cylindrical lens. The curved surface of the fifth lens 51 is located in the first plane (xz plane). For a light beam passing through the fifth lens 51 along the z direction, the cross-section of the fifth lens 51 in the yz plane is a plane, while the cross-section in the xz plane is a curved surface. In the xz plane (first plane), when the light beam passes through the fifth lens 51, the fifth lens 51 will refract the light beam, and the propagation direction of the light beam will change. In the yz plane (second plane), when the light beam passes through the fifth lens 51, the propagation direction of the light beam remains unchanged.

[0122] That is, in the embodiments of this application, see Figure 10 As shown, in the first plane, the multiplexed light input from input port 11 illuminates the fifth lens 51. Figure 10 The solid line in the middle illustrates the optical path from the input port 11 to the switching engine 30. After being expanded by the fifth lens 51, the light is emitted in a direction parallel to the second plane and illuminates the first lens 41. After passing through the first lens 41 and the second lens 42 in sequence, the light is illuminated in a direction parallel to the second plane and illuminates the dispersive element 20. The dispersive element 20 disperses the multiplexed light and emits multiple sub-beams. After passing through the third lens 43 and the fourth lens 44 in sequence, the multiple sub-beams are illuminated in a direction parallel to the second plane and illuminate the switching engine 30. The switching engine 30 deflects the multiple sub-beams at a preset angle and emits them to form a deflector beam.

[0123] The eccentric beam passes sequentially through the fourth lens 44, the third lens 43, the dispersive element 20, the second lens 42, and the first lens 41. Figure 10 The dashed line in the diagram illustrates the optical path from the switching engine 30 to the output port 12. The light beam is refracted by the fifth lens 51, thus directing it to the output port. It should be understood that when at least one wavelength sub-beam of the deflection beam after passing through the switching engine 30 has a different deflection angle than other wavelength sub-beams, the incident angles of the beams after passing through the first lens group 40 and the dispersive element 20 and then illuminating the fifth lens 51 are also different. Consequently, the exit angles are also different, allowing the separated beams to be refracted to different output ports 12, thereby achieving the scheduling and distribution of signal wavelengths.

[0124] The focal length of the fifth lens 51 can be f5, and the switching lens group 50 can be a 2f optical system, where f is the focal length of the fifth lens 51, and f = f5.

[0125] Correspondingly, the fifth lens 51 can be a single lens element, or it can be composed of two or more lens elements, which can be equivalent to a lens in the optical path to achieve the optical path effect of the fifth lens 51.

[0126] Figure 11 This is a schematic diagram of the optical path of another wavelength selective switch in the second plane, provided as an embodiment of this application.

[0127] In the embodiments of this application, see Figure 11 As shown, the wavelength selection switch also includes a second lens group 60. In the second plane (yz plane), the dispersive element 20 is located in the second lens group 60. The second lens group 60 can illuminate the multiplexed light input from the input port 11 onto the dispersive element 20 in a direction parallel to the first plane (xz plane).

[0128] The second lens group 60 can also converge the sub-beams dispersed by the dispersive element 20 and direct them onto the switching engine 30. That is, after passing through the second lens group 60, the multiple sub-beams emitted by the dispersive element 20 can be converged onto different areas of the switching engine 30. The second lens group can also be used to control the light spot.

[0129] For details, see Figure 11 As shown, the second lens group 60 may include a sixth lens 61 and a seventh lens 62, and the dispersive element 20 may be located in the optical path between the sixth lens 61 and the seventh lens 62.

[0130] The sixth lens 61 and the seventh lens 62 can be cylindrical lenses, and the curved surface of the sixth lens 61 is located in the second plane, that is, for a light beam passing through the sixth lens 61 along the z direction, the cross section of the sixth lens 61 in the x-z plane is a plane, and the cross section in the y-z plane is a curved surface. In the y-z plane (the second plane), the propagation direction of the light beam changes when the light beam passes through the sixth lens 61, and in the x-z plane (the first plane), the propagation direction of the light beam remains unchanged when the light beam passes through the sixth lens 61.

[0131] Correspondingly, the curved surface of the seventh lens 62 is also located in the second plane, and in the y-z plane (the second plane), the propagation direction of the light beam changes when the light beam passes through the seventh lens 62, and in the x-z plane (the first plane), the propagation direction of the light beam remains unchanged when the light beam passes through the seventh lens 62.

[0132] Specifically, in the second plane (the y-z plane), the multiplexed light passes through the sixth lens 61, and the sixth lens 61 performs beam expansion processing on the multiplexed light, so that the multiplexed light is irradiated on the dispersion element 20 in a direction parallel to the first plane, that is, the sixth lens 61 expands the multiplexed light to increase the spot area.

[0133] The seventh lens 62 can converge each sub-beam dispersed by the dispersion element 20, so that the plurality of sub-beams are irradiated on different regions of the switching engine 30, so that the switching engine 30 can realize independent processing of each wavelength beam and realize scheduling and distribution of signal wavelengths.

[0134] Continuing to refer to Figure 11 As shown, the back focal surface of the sixth lens 61 can coincide with the dispersion element 20, and the front focal surface of the seventh lens 62 can also coincide with the dispersion element 20. Then, in the second lens group 60, the distance between the front focal surface of the sixth lens 61 and the back focal surface of the seventh lens 62 is f6+f6+f7+f7, where f6 is the focal length of the sixth lens 61, and f7 is the focal length of the seventh lens 62.

[0135] Here, the focal length f6 of the sixth lens 61 and the focal length f7 of the seventh lens 62 can be equal, such as f, and the second lens group 60 is a 4f optical system. The second lens group 60 can also play a role of relay to realize control of the optical path and the spot.

[0136] Of course, in some other examples, the focal length f6 of the sixth lens 61 and the focal length f7 of the seventh lens 62 can also be unequal.

[0137] Correspondingly, the sixth lens 61 and the seventh lens 62 can also be single lenses respectively, or the sixth lens 61 and the seventh lens 62 can also be composed of two or more lens elements, and the optical paths of the sixth lens 61 and the seventh lens 62 can be equivalent.

[0138] Continuing to refer to Figure 11 As shown, the wavelength selection switch 100 further includes a third lens group 70, which can be located on the optical path between the input port 11 and the second lens group 60, and can irradiate the multiplexed light input by the input port 11 to the second lens group 60 in the second plane (y-z plane).

[0139] That is, the multiplexed light input from the input port 11 is irradiated to the second lens group 60 after passing through the third lens group 70, and specifically, to the sixth lens 61 of the second lens group 60. The third lens 43 can also control the optical path and spot size of the multiplexed light.

[0140] Specifically, referring to Figure 11 As shown, the third lens group 70 can include an eighth lens 71 and a ninth lens 72, the eighth lens 71 can be located on the optical path between the input port 11 and the ninth lens 72, and the eighth lens 71 and the ninth lens 72 can be cylindrical lenses.

[0141] The curved surface of the eighth lens 71 is located in the second plane, that is, for the light beam passing through the eighth lens 71 along the z direction, the cross section of the eighth lens 71 in the x-z plane is a plane, and the cross section in the y-z plane is a curved surface. In the y-z plane (second plane), when the light beam passes through the eighth lens 71, the eighth lens 71 will refract the light beam, and the propagation direction of the light beam will change, while in the x-z plane (first plane), the propagation direction of the light beam remains unchanged when the light beam passes through the eighth lens 71.

[0142] Correspondingly, the curved surface of the ninth lens 72 is also located in the second plane, and in the y-z plane (second plane), the propagation direction of the light beam changes when the light beam passes through the ninth lens 72, while in the x-z plane (first plane), the propagation direction of the light beam remains unchanged when the light beam passes through the ninth lens 72.

[0143] Specifically, in the second plane (y-z plane), the multiplexed light input from the input port 11 passes through the eighth lens 71, and the eighth lens 71 can expand the multiplexed light to irradiate the multiplexed light to the ninth lens 72 in the direction parallel to the first plane.

[0144] The ninth lens 72 can converge the multiplexed light and irradiate the second lens group 60, specifically, the sixth lens 61. The multiplexed light is expanded by the eighth lens 71 and then converged by the ninth lens 72, so that the third lens group 70 controls the light spot and reduces the phenomenon of increasing the light spot with the transmission of the multiplexed light.

[0145] Continuing to refer to Figure 11 As shown, the back focal surface of the eighth lens 71 can coincide with the front focal surface of the ninth lens 72 (the part of the dashed line is the coincident position), so that in the third lens group 70, the distance between the front focal surface of the eighth lens 71 and the back focal surface of the ninth lens 72 is f8+f8+f9+f9, where f8 is the focal length of the eighth lens 71 and f9 is the focal length of the ninth lens 72. Figure 11

[0146] Wherein, the focal length f8 of the eighth lens 71 and the focal length f9 of the ninth lens 72 can be equal, such as both f, then the third lens group 70 is a 4f optical system, the third lens group can also play a relay role to realize the regulation of the light path and the light spot, and the light spot on the front focal surface of the eighth lens coincides with the light spot on the back focal surface of the ninth lens.

[0147] Of course, in some other examples, the focal length f8 of the eighth lens 71 and the focal length f9 of the ninth lens 72 can also be unequal.

[0148] Correspondingly, the eighth lens 71 and the ninth lens 72 can also be single lenses respectively, or the eighth lens 71 and the ninth lens 72 can also be composed of two or more lens elements, which can be equivalent to the eighth lens 71 and the ninth lens 72 in the optical path. Wherein, the eighth lens 71 and the ninth lens 72 can also share one or more lens elements, which can be equivalent to respectively realize the optical path effect of the eighth lens 71 and the ninth lens 72.

[0149] Wherein, it should be noted that when the switching engine 30 is a polarization-dependent channel switching device, for example, the switching engine 30 is a liquid crystal on silicon chip, the wavelength selection switch 100 can also include a polarization optical element (not shown in the figure). Specifically, the polarization optical element can be located between the third lens group 70 and the second lens group 60, or the polarization optical element can be located in the third lens group 70, specifically, between the eighth lens 71 and the ninth lens 72. The polarization optical element can realize polarization adjustment, so as to facilitate the channel switching of the switching engine 30.

[0150] ​In the description of the embodiments of the present application, it should be noted that unless specifically defined and limited otherwise, the terms "mount", "connect", "connection" should be understood broadly, for example, can be fixed connection, can also be indirectly connected through the intermediate medium, can be the internal communication of two elements or the interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances. The terms "first", "second", "third", "fourth" and the like (if any) are used to distinguish similar objects, and do not necessarily describe a specific order or sequence.

[0151] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, not to limit them; although the embodiments of the present application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A wavelength selective switch, characterized by, The input-output port group includes an input port and a plurality of output ports arranged in a first plane, the input port being configured to input multiplexed light including a plurality of sub-beams of different wavelengths; The switching engine is configured to output the plurality of sub-beams from the corresponding output ports after the sub-beams are deflected by a preset deflection angle in the first plane to form deflected sub-beams, and the deflected sub-beams pass through the first lens group and the dispersion element. The first lens group includes a first lens, a second lens, a third lens and a fourth lens, the dispersion element is located between the second lens and the third lens in the first plane, the first lens is configured to irradiate the multiplexed light onto the second lens in the first plane, the second lens is configured to irradiate the multiplexed light passing through the first lens to the dispersion element in a direction parallel to the second plane in the first plane, the third lens is configured to irradiate the sub-beams dispersed by the dispersion element onto the fourth lens in the first plane, and the fourth lens is configured to irradiate the sub-beams passing through the third lens to the switching engine in a direction parallel to the second plane in the first plane. The second lens group is configured to irradiate the multiplexed light to the dispersion element in a direction parallel to the first plane in the second plane, and the second lens group is further configured to irradiate the sub-beams dispersed by the dispersion element to the switching engine in the second plane. The switching lens group is configured to expand the multiplexed light in the first plane and irradiate the multiplexed light to the first lens group in a direction parallel to the second plane.

2. The wavelength selective switch of claim 1, wherein, The switching lens group is further configured to refract the deflected sub-beams passing through the first lens group and the dispersion element to the corresponding output ports in the first plane. The switching lens group includes a fifth lens, and a curved surface of the fifth lens is located in the first plane.

3. The wavelength selective switch of claim 2, wherein, The second lens group includes a sixth lens and a seventh lens.

4. The wavelength selective switch according to any of claims 1-3, wherein, The sixth lens is configured to expand the multiplexed light in the second plane and irradiate the multiplexed light to the dispersion element.

5. The wavelength selective switch according to any of claims 1-3, wherein, The seventh lens is configured to refract the deflected sub-beams passing through the first lens group and the dispersion element to the corresponding output ports in the second plane. ​ 6. The wavelength selective switch of claim 5, wherein, ​ 7. The wavelength selective switch of claim 1, wherein, ​ ​ The seventh lens is configured to converge the sub-beams dispersed by the dispersion element respectively in the second plane, so that the sub-beams are respectively irradiated on different regions of the switching engine.

8. The wavelength selective switch of claim 7, wherein, The back focal plane of the sixth lens coincides with the dispersion element, and the front focal plane of the seventh lens coincides with the dispersion element.

9. The wavelength selective switch of claim 8, wherein, The focal length of the sixth lens is equal to the focal length of the seventh lens.

10. The wavelength selective switch according to any of claims 6-9, wherein, A third lens group is further included, which is configured to irradiate the multiplexed light to the second lens group in the second plane.

11. The wavelength selective switch of claim 10, wherein, The third lens group includes an eighth lens and a ninth lens, the eighth lens is configured to expand the multiplexed light after the multiplexed light passes through the eighth lens and irradiate the multiplexed light to the ninth lens in the second plane; The ninth lens is configured to converge the multiplexed light passing through the eighth lens and irradiate the multiplexed light to the second lens group in the second plane.

12. The wavelength selective switch of claim 11, wherein, The back focal plane of the eighth lens coincides with the front focal plane of the ninth lens.

13. The wavelength selective switch of any of claims 1-3, 6-9, 11-12, wherein, The number of the input and output port groups is multiple; Multiple input and output port groups are stacked in the first plane.

14. The wavelength selective switch of any of claims 1-3, 6-9, 11-12, wherein, The dispersion element includes a grating or a prism.

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