WO2023221802A1

WO2023221802A1 - Wavelength selective switch

Info

Publication number: WO2023221802A1
Application number: PCT/CN2023/092775
Authority: WO
Inventors: 郑柱军; 潘煦; 杨海宁
Original assignee: 华为技术有限公司
Priority date: 2022-05-16
Filing date: 2023-05-08
Publication date: 2023-11-23
Also published as: CN117111218A

Abstract

A wavelength selective switch (100), comprising a dispersive element (20) and a switching engine (30). The dispersive element (20) can disperse multiplexed light input from input ports (11) into multiple sub-beams in a dispersive plane, and irradiate same to the switching engine (30); the switching engine (30) can deflect the multiple sub-beams according to preset deflection angles in a switching plane to form deflected sub-beams, and output the deflected sub-beams from corresponding output ports (12); and the deflection angles of one wavelength beam and other wavelength beams are different, such that the wavelength beam can be separated and output from a different output port (12), thereby achieving the scheduling and allocation of signal wavelengths. A first lens group (40) is further comprised; the first lens group (40) can irradiate the multiplexed light to the dispersive element (20) in a direction parallel to the dispersive plane in the switching plane, and irradiate the sub-beams dispersed by the dispersive element (20) to the switching engine (30), thereby eliminating an inclined incident angle between the multiplexed light and the dispersive element (20), reducing the conical diffraction effect of the dispersive element (20), and improving the filter passband performance of the wavelength selective switch (100).

Description

Wavelength Selective Switch

This application claims priority to the Chinese patent application filed with the China Patent Office on May 16, 2022, with application number 202210530968.X and application name "Wavelength Selective Switch", the entire content of which is incorporated into this application by reference.

Technical field

The present application relates to the field of communication technology, and in particular to a wavelength selective switch.

Background technique

With the continuous development of optical communication technology, Wavelength Division Multiplexing (WDM) is a common optical layer networking technology. By multiplexing different wavelengths in one optical fiber for transmission, it is easy to achieve large-capacity transmission. Reconfigurable Optical Add-Drop Multiplexer (ROADM), as the core optical switching device in the WDM network, can select and configure any wavelength on any port. Among them, the Wavelength Selective Switch (WSS for short) is the core optoelectronic device of the reconfigurable optical add-drop multiplexer. It can realize the switching, attenuation or blocking of optical signals of any wavelength or any combination of wavelengths at any port. It is one of the important devices in the current optical communication industry. .

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. Among them, the shaping system processes the spot of the beam entering from the input port, and the optical system processes the light spot after the shaping system. The optical path and spot size of the beam are controlled. The dispersion element can spatially split or combine the light of different wavelengths in the beam and illuminate it to the switching engine. The switching engine angularly deflects and attenuates the light of each wavelength. Control, and then output the split or combined split waves of different wavelengths in different directions through the corresponding output ports. In a common wavelength selective switch, on the switching plane, the optical system is a 4f optical system composed of lenses. 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 is The front focal planes of the second lens coincide with each other, and the dispersion element is located on the coincident plane, that is, the dispersion element is located in the middle of the first lens and the second lens.

However, in the above-mentioned wavelength selective switch, the incident light beam is incident on the dispersive element obliquely on the switching plane. Due to the cone diffraction effect of the dispersive element, the light spot illuminated on the switching engine will be crescent-shaped, affecting the performance of the wavelength selective switch. Filter passband performance.

Contents of the invention

This application provides a wavelength selective switch that can reduce the cone diffraction effect of the dispersion element on the switching plane, thereby improving the filter passband performance of the wavelength selective switch.

The present application provides a wavelength selective switch, which includes an input and output port group. The input and output port group includes an input port and a plurality of output ports stacked in a first plane. The input port is used to input multiplexed light. The multiplexed light includes multiple sub-beams of different wavelengths.

It also includes a dispersion element and a switching engine. The dispersion element is configured to disperse the multiplexed light input from the input port into multiple sub-beams in the second plane, and irradiate the multiple sub-beams to different areas of the switching engine respectively. First Plane and The second plane is orthogonal. That is to say, in the second plane, the dispersion element can split the multiplexed light into multiple sub-beams and illuminate them on different areas of the switching engine, so that the switching engine can realize the control of each wavelength channel. Independent control.

It also includes a first lens group, the dispersive element is located in the first lens group in the first plane, and the first lens group is configured to illuminate the multiplexed light onto the dispersive element in a direction parallel to the second plane in the first plane. , the first lens group is further configured to illuminate the sub-beam emitted from the dispersion element onto the switching engine in the first plane. That is, in the first plane, the multiplexed light input from the input port passes through the first lens group and is illuminated on the dispersion element in a direction parallel to the second plane, and the sub-beam emitted from the dispersion element is illuminated on the dispersion element through the first lens group. On the switching engine, the switching engine can realize individual control of each sub-beam.

The switching engine can individually control the sub-beams of different wavelengths incident on the switching engine in the first plane, thereby changing the transmission angle of each sub-beam on the first plane, thereby controlling the sub-beams of each wavelength from the corresponding output port output. Specifically, the switching engine can emit multiple 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 then be output from the output port, so that the sub-beams are Different deflection angles can illuminate different output ports accordingly. If the deflection angle of the sub-beam of one wavelength is different from that of the sub-beam of other wavelengths, the deflected sub-beam of this wavelength can be irradiated to the corresponding output port, thereby realizing the separation and output of the signal of this wavelength, and thus realizing the signal processing. Wavelength scheduling and allocation. Since the multiplexed light input from the input port in the first plane can be illuminated on the dispersion element in a direction parallel to the second plane through the first lens group, the complex light in the switching plane (first plane) is reduced or eliminated. The inclined incident angle between the light and the dispersive element reduces or avoids the difference in the incident angle of each sub-beam in the multiplexed light on the dispersive element, thereby significantly reducing the cone diffraction effect of the dispersive element and improving the light spot shape. appearance, thereby significantly improving the filter passband performance of the wavelength selective switch.

In addition, it also helps to reduce the difference in the incident angle of each deflected sub-beam on the dispersive element when the deflected sub-beam returns and passes through the dispersive element, which helps to reduce the insertion loss of the wavelength selective switch and further improves the performance of the wavelength selective switch.

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.

The first lens is configured to illuminate 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 illuminate the sub-beams dispersed by the dispersion element onto the fourth lens in the first plane.

The fourth lens is configured to illuminate the sub-beam passing through the third lens onto the switching engine in a direction parallel to the second plane in the first plane. That is to say, in the first plane, the multiplexed light input from the input port is refracted by the first lens and then irradiated onto the second lens. The second lens refracts the multiplexed light that has passed through the first lens, so that the multiplexed light The dispersive element is illuminated in a direction parallel to the second plane, thereby reducing the incident angle difference of each sub-beam in the multiplexed light on the dispersive element, thereby achieving the purpose of reducing the cone diffraction effect of the dispersive element.

The sub-beam dispersed by the dispersion element is refracted by the third lens and then irradiated to the fourth lens. The fourth lens refracts it again so that the sub-beam is irradiated to the switching engine in a direction parallel to the second plane, thereby facilitating the switching engine to achieve alignment. The deflection of the sub-beams to form deflected sub-beams ensures the individual control of the sub-beams by the switching engine.

In a possible implementation, the back focal plane of the first lens coincides with the front focal plane of the second lens, and the back focal plane of the second lens coincides with the dispersion element.

The front focal plane of the third lens coincides with the dispersion element, and the back focal plane of the third lens coincides with the front focal plane of the fourth lens.

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. If they are all f, then the first lens group is an 8f optical system. The first lens group can play a relay role, that is, the light beam passing through the first lens group maintains its original optical characteristics (such as the size of the light beam, propagation direction, etc.), so that the light spot on the front focal surface of the first lens can be aligned with the fourth lens group. The spot size on the rear focal surface of the lens is consistent, and the spot size is controlled through the first lens group, which helps improve the filter passband performance of the wavelength selective switch.

In a possible implementation, the dispersion element is located between the second lens and the third lens, so that the multiplexed light can be illuminated to the dispersion element in a direction parallel to the second plane, thereby reducing the cone diffraction effect, thus facilitating Improved the appearance of light spots on the switching engine.

In a possible implementation, a switching lens group is further included, and the switching lens group is configured to expand the multiplexed light in the first plane and then illuminate it to the first lens group in a direction parallel to the second plane. That is to say, in the first plane, the multiplexed light input from the input port passes through the switching lens group, and the switching lens group can expand the beam of the multiplexed light, so that the multiplexed light passes along the direction parallel to the second plane. direction to illuminate the first lens group. Switching the lens group can realize the magnification of the light spot in the first plane, increase the light spot area, and realize the control of the light spot.

The switching lens group is also configured to switch the deflected sub-beams regulated by the switching engine to different output ports, that is, on the first plane, the switching lens group can refract the deflected sub-beams after passing through the first lens group and the dispersion element to the corresponding The output port outputs to realize the scheduling and distribution of signal wavelengths.

In a possible implementation, the switching lens group includes a fifth lens. The curved surface of the fifth lens is located on the first plane, that is, within the first plane. The fifth lens will refract the light beam passing through it, so that It plays the role of beam expansion for the multiplexed light input from the input port, and plays the role of refraction and deflection of the deflected sub-beams after passing through the first lens group and the dispersion element, so that they are refracted to the corresponding output ports respectively, thereby realizing the signal wavelength adjustment. Scheduling and allocation.

In a possible implementation, it also includes a second lens group, 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 beam and combine it in the second plane. Illumination to the dispersive element.

The second lens group is also configured to irradiate the sub-beams dispersed by the dispersive element to the switching engine in the second plane. That is, the multiple sub-beams emitted by the dispersive element can be converged to different parts of the switching engine after passing through the second lens group. In terms of area, the light spot can be controlled through the second lens group.

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

The sixth lens is configured to expand the multiplexed light beam in the second plane and then illuminate it to the dispersion element.

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 respectively illuminate different areas of the switching engine. That is, in the second plane, the multiplexed light passes through the sixth lens, and the sixth lens performs beam expansion processing on the multiplexed light, and then irradiates the multiplexed light onto the dispersion element. The seventh lens can separately converge the sub-beams dispersed by the dispersion element, so that the multiple sub-beams are illuminated on different areas of the switching engine, so that the switching engine can independently process the beams of each wavelength and realize the scheduling and control of signal wavelengths. distribute.

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.

In a possible implementation, the focal length of the sixth lens and the focal length of the seventh lens are equal. If both are f, then the second lens group is a 4f optical system, and the second lens group can play a relay role, achieving The light spot is controlled so that the light spot on the front focal plane of the sixth lens is consistent in size with the light spot on the back focal plane of the seventh lens.

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

In a possible implementation, the third lens group includes an eighth lens and a ninth lens, and the eighth lens is configured to expand the multiplexed light in the second plane and then illuminate it to the ninth lens.

The ninth lens is configured to converge the multiplexed light passing through the eighth lens in the second plane and irradiate it to the second lens group, so that the multiplexed light passes through the eighth lens and then is expanded by the ninth lens and then converged through the ninth lens. The three-lens group realizes control of the light spot and reduces the phenomenon of the light spot increasing with multiplexed light transmission.

In a possible implementation, the back focal plane of the eighth lens coincides with the front focal plane of the ninth lens. The focal length of the eighth lens can be equal to the focal length of the ninth lens. If both are f, the third lens group is a 4f optical system. The third lens group also plays a relay role to control the optical path and light spot, so that the third lens group can The size of the light spot on the front focal surface of the eighth lens is consistent with the size of the light spot on the rear focal surface of the ninth lens.

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. This can realize the integration of multiple optical signals, so that multiple beams of multiplexed light can be input into the wavelength selective switch at the same time, thus helping to reduce the cost of the entire transmission system.

In a possible implementation, the dispersive element includes a grating or a prism.

Description of the drawings

Figure 1 is a schematic structural diagram of an all-optical network system provided by an embodiment of the present application;

Figure 2 is a schematic structural diagram of an optical switching node provided by an embodiment of the present application;

Figure 3 is a schematic structural diagram of a wavelength selective switch provided by an embodiment of the present application;

Figure 4 is a schematic diagram of an optical path in a switching plane of a wavelength selective switch in the related art;

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

Figure 6 is a schematic diagram of an optical path in a second plane of a wavelength selective switch provided by an embodiment of the present application;

Figure 7 is a schematic diagram of an optical path in a first plane of a wavelength selective switch provided by an embodiment of the present application;

Figure 8 is a schematic diagram of a light spot formed on a switching engine in a wavelength selective switch provided by an embodiment of the present application;

Figure 9 is a schematic diagram of an optical path in a first plane of another wavelength selective switch provided by an embodiment of the present application;

Figure 10 is a schematic diagram of an optical path for channel switching of a wavelength selective switch provided by an embodiment of the present application;

FIG. 11 is a schematic diagram of an optical path in a second plane of another wavelength selective switch provided by an embodiment of the present application.

Explanation of reference symbols:
100-Wavelength selection switch; 10-Input and output port group; 11-Input port;
12-Output port; 20-Dispersion element; 30-Switching engine;
40-First lens group; 41-First lens; 42-Second lens;
43-Third lens; 44-Fourth lens; 50-Switching lens group;
51-Fifth lens; 60-Second lens group; 61-Sixth lens;
62-Seventh lens; 70-Third lens group; 71-Eighth lens;
72-Ninth lens.

Detailed ways

The terms used in the embodiments of the present application are only used to explain specific embodiments of the present application and are not intended to limit the present application.

The embodiment of the present application provides a wavelength selective switch, which can be applied in optical fiber communication technology, especially suitable for In the trunk line or metropolitan area network system of long-distance optical fiber communication, it is used to realize the scheduling of signal wavelengths, that is, the uploading and downloading of signals, so that the wavelength allocation can be realized remotely and dynamically, improving work efficiency and shortening the response to user needs. time.

Specifically, the wavelength selective switch can be applied to the All Optical Network (AON) system. The all-optical network system means that the signal always exists in the form of an optical signal during the transmission, exchange, and amplification process in the network. , without electrical signal processing, only electrical-to-optical and optical-to-electrical conversion is performed when entering and exiting the network. Since AON is a direct optical fiber communication network composed of optical fiber as the optical propagation medium, it is not affected by the response speed of electronic equipment in traditional networks. It can effectively reduce network delay and system power consumption and is widely used. Among them, AON based on Dense Wavelength Division Multiplexing (DWDM) technology can realize high-speed and large-capacity information transmission and processing, which is one of the main communication development trends.

Among them, AON uses optical switching nodes to replace the electrical nodes of traditional networks. In order to meet the dynamic needs of network traffic, optical switching nodes need to have the ability to allocate resources on demand. In addition, due to the increase in network services, optical switching nodes need to have multi-dimensional uplink and downlink functions. port, making full use of the network capacity of wavelength division multiplexing technology to perform multi-dimensional service scheduling. Optical switching nodes can be composed of Reconfigurable Optical Add-Drop Multiplexer (ROADM). ROADM is a device that can add, block, penetrate, or redirect optical signals of different wavelengths in an optical fiber communication network. , through remote reconfiguration, the add-on or drop-off service wavelength can be dynamically configured according to needs to achieve flexible service scheduling. The wavelength selective switch has the function of selecting and outputting a specific wavelength from the input wavelength. It can demultiplex the optical signal of any input port and any wavelength and schedule it to any output port without blocking. It can be used in ROADM. It can be used as a key module to implement multi-dimensional, flexible ROADM. In other words, the wavelength selective switch can realize optical signal switching, optical signal attenuation or optical signal blocking of any wavelength or any combination of wavelengths at any port.

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

The following is a brief description of the application scenarios of wavelength selective switches using wavelength selective switches applied in all-optical network systems.

FIG. 1 is a schematic architectural diagram of an all-optical network system provided by an embodiment of the present application, and FIG. 2 is a schematic structural diagram of an optical switching node provided by an embodiment of the present application.

Specifically, as shown in Figure 1, the all-optical network system may include a backbone network ring 300 and an access network ring 400. The backbone network ring 300 may include multiple optical switching nodes 301. Specifically, the optical switching nodes 301 may It is a ROADM that can dynamically configure add-on or drop-off service wavelengths according to needs to achieve flexible scheduling of services. The backbone network ring 300 also includes an add-on user terminal 302. The access network ring 400 may include multiple drop user terminals 401. The access network ring 400 performs add/drop services with the backbone network ring 300 through the optical switching node 301 to realize communication between the add user terminal 302 and the drop user terminal 401. , where the add/drop service refers to the optical signal transmission between the access network ring 400 and the backbone network ring 300 . The drop client 401 may refer to a connection device that can be provided to the user 402, for example, it may be a voice and/or data connection device, or it may also be a computer device such as a laptop computer or a desktop computer, or it may be such as Independent devices such as Personal Digital Assistant (PDA for short) are not limited in the embodiments of this application.

As shown in Figure 2, the optical switching node is a ROADM and may include multiple wavelength selective switches 100. The wavelength selective switches 100 can realize any cross-interconnection of optical signals between the access network ring 400 and the backbone network ring 300, and It can dynamically adjust the add/drop of each switching node in the all-optical network, thereby realizing wavelength allocation between each optical switching node in the all-optical network.

It should be understood that the optical switching node may also include other devices, such as fiber amplifiers, waveguide gratings, etc., which are not limited in the embodiments of this application.

FIG. 3 is a schematic structural diagram of a wavelength selective switch provided by an embodiment of the present application.

As shown in FIG. 3 , the wavelength selective switch 100 may include an input port 11 , an output port 12 and a demultiplexing device 101 . The input port 11 may be composed of an optical fiber and may allow light beams to enter the wavelength selective switch 100 . Specifically, the input port 11 is used to input multiplexed light. The multiplexed light may include multiple sub-beams of different wavelengths. In other words, the multiplexed light may include sub-beams with wavelengths of λ1, λ2, λ3, λ4, λ5...λm. ,m≥2. The multiplexed light can enter the wavelength selective switch 100 through the input port 11.

The multiplexed light may be formed by multiplexing sub-beams of different wavelengths together through DWDM technology. The wavelength of each sub-beam in the multiplexed light can be a wavelength commonly used in DWDM communication systems, and the specific wavelength value can be selected and set according to needs.

The wavelength demultiplexing device 101 can separate the multiplexed light input from the input port 11, separate the sub-beams of at least one wavelength in the multiplexed light from the sub-beams of other wavelengths in the multiplexed light, and separate the separated sub-beams from the corresponding sub-beams. The output port 12 is output to the outside of the wavelength selective switch 100, so that the sub-beams of the wavelength are separated to realize the scheduling of the signal wavelength, and the wavelength allocation can be realized remotely and dynamically. It should be noted that the separated sub-beams may include sub-beams of one required wavelength, or the separated sub-beams may include sub-beams of two or more required wavelengths. The specific separation method can be selected and set according to the needs of the communication system.

For example, taking the multiplexed light including sub-beams with five wavelengths of λ1, λ2, λ3, λ4, and λ5, the wavelength demultiplexing device 101 separates the multiplexed light and can separate the wavelengths of λ1, λ3, and λ5. The sub-beams of the three wavelengths are separated respectively (refer to Figure 3), and are output from the corresponding output ports 12 respectively. After separation, the sub-beams with wavelength λ2 and wavelength λ4 can be combined together to form a beam, which is output from the corresponding output port 12 .

It should be understood that the number of the output ports 12 may be multiple to achieve the output of the separated light beams. Specifically, the number of output ports 12 can be consistent with the number of light beams separated by the wavelength splitting device 101, so as to meet the output requirements of the separated light beams.

Among them, the input port 11 and the output port 12 can be arranged in a stacked manner in one direction. In the embodiment of the present application, the direction in which the input port 11 and the output port 12 are arranged is the x direction (see Figure 7), which will be perpendicular to The propagation direction of the multiplexed light input from the input port 11 in 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 first plane 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 second plane is the y-z plane, and the second plane is orthogonal to the first plane.

The first plane can be used as the switching plane of the wavelength selective switch 100 , and the second plane can be used as the dispersion plane of the wavelength selective switch 100 . In the dispersion plane, the multiplexed light entering from the input port 11 is dispersed into multiple sub-beams of different wavelengths, thereby achieving separate processing of signals of each wavelength. In the switching plane, the sub-beams of different wavelengths are adjusted and controlled, for example, the sub-beams of different wavelengths are deflected by a preset angle, etc., so that they are output from the corresponding output port 12 .

Among them, the wavelength splitting device may include a dispersion unit and a switching engine. The dispersion unit is used to separate multiplexed light. The dispersion unit may be an optical element capable of splitting light such as a grating. For example, taking a grating as an example, on the dispersion plane Inside, the grating can disperse the multiplexed light passing through it into multiple sub-beams, each of which has an unequal wavelength. The dispersion element disperses the multiplexed light into multiple sub-beams and irradiates them to different areas of the switching engine. , forming a light on the switching engine spot. In the switching plane, the switching engine can realize independent control of sub-beams of different wavelengths to achieve separate output of specific wavelength signals.

Specifically, the switching engine can deflect multiple sub-beams so that the multiple sub-beams are deflected according to preset angles, and the switching engine can regulate different areas to achieve independent control of sub-beams of different wavelengths. It is possible to control the deflection angle of each sub-beam, and by making the deflection angles different, the deflected sub-beams of each wavelength can be output from the corresponding output port, thereby realizing channel switching.

FIG. 4 is a schematic diagram of an optical path in a switching plane of a wavelength selective switch in the related art. FIG. 5 is a schematic diagram of the light spot formed on the switching engine of the wavelength selective switch in the related art.

Specifically, the wavelength selective switch also includes an imaging system 4. The grating 3 is located in the imaging system 4. In the switching plane (x-z plane in Figure 4), the multiplexed light input from the input port 1a passes through the imaging system 4. After being illuminated on the switching engine 5, the imaging system 4 can adjust and control the light path and the size of the light spot.

The imaging system 4 may be composed of a lens. Specifically, a common imaging system 4 is mostly a 4f optical system composed of lenses, where f is the focal length of the lens. For example, as shown in FIG. 4 , the imaging system 4 may include a first lens 4a and a second lens 4b. The back focal plane of the first lens 4a and the front focal plane of the second lens 4b coincide with each other. The first lens 4a and the second lens 4b overlap. The focal length of the two lenses 4b is f. The switching engine 5 can be located on the back focal plane of the second lens 4b. The distance between the front focal plane of the first lens 4a and the back focal plane of the second lens 4b is 4f.

The grating 3 may 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 to say, in the switching plane (x-z plane), along the z direction passing through the first lens 4a and the second lens 4b The light beam will be refracted by the first lens 4a and the second lens 4b.

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. After passing through the grating 3, it is irradiated to the second lens 4b and is refracted by the second lens 4b. Switch on engine 5.

The grating 3 is located in the middle of the 4f optical system. As shown in Figure 4, in the switching plane, when the multiplexed light refracted by the first lens 4a converges and illuminates the grating 3, an inclined angle will be formed between the multiplexed light and the grating 3. The 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), the conical diffraction (Conical diffraction) phenomenon of the grating 3 is prone to occur. Specifically, the multiplexed light is incident at an oblique angle, and the incident angles of each sub-beam in the multiplexed light relative to the grating 3 are different. Correspondingly, the exit angles of each sub-beam after being diffracted by the grating 3 will also be different. This is This phenomenon is the cone diffraction phenomenon. Due to the cone diffraction phenomenon, after the sub-beam is irradiated onto the switching engine 5, a meniscus-shaped spot 5a as shown in Figure 5 will be formed on the switching engine 5. In this way, when channel switching is implemented through the switching engine, part of the sub-beams will be missing, which will affect the deflection accuracy of each sub-beam, thereby affecting the filter passband performance of the wavelength selective switch.

Moreover, when the sub-beam is deflected by the switching engine 5 and returns to the original path, the incident angle between the sub-beam and the grating 3 may further increase, cone diffraction will occur again, and the light spot will be further distorted, causing the sub-beam passing through the grating 3 to The beam spot shape is difficult to restore to standard Gaussian light, which affects the insertion loss of the wavelength selective switch and further reduces the performance of the wavelength selective switch.

Based on this, embodiments of the present application provide a wavelength selective switch that can significantly reduce the cone diffraction phenomenon of dispersive elements such as gratings, improve the filter passband performance of the wavelength selective switch, and reduce the insertion loss of the wavelength selective switch.

The optical path structure of the wavelength selective switch in the switching plane and the dispersion plane will be described in detail below with reference to the accompanying drawings.

FIG. 6 is a schematic diagram of an optical path in a second plane of a wavelength selective switch provided by an embodiment of the present application.

Among them, in the embodiment of the present application, a beam of multiplexed light including multiple sub-beams of different wavelengths is used as an example for description. The first plane is an x-z plane, and the first plane may be a switching plane of the wavelength selective switch. The second plane is the y-z plane, and the second plane may be the dispersion plane of the wavelength selective switch 100 .

The wavelength selective switch includes a dispersion element 20 and a switching engine 30, wherein the dispersion element 20 can be a grating, or the dispersion element 20 can also be a grating, and the prism can include a prism and a grating. Of course, in some examples, the dispersion element 20 can also be other optical elements capable of splitting light.

The switching engine 30 can be a Liquid Crystal on Silicon (LCOS for short), or the switching engine 30 can also be a Micro-Electro-Mechanical System (MEMS for short), or the switching engine 30 can also be Digital Light Processing (DLP), or the switching engine 30 can also be a liquid crystal switching chip or other chips that can realize optical path switching.

Specifically, the dispersion element 20 may 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 may be located in the second plane. As shown in Figure 6, in other words, in the y-z plane, when the multiplexed light input from the input port 11 along the z direction passes through the dispersion element 20, the dispersion element 20 can play a role in splitting the multiplexed light, so that the incident multiplexed light Beams of different wavelengths in the light are dispersed at different angles in space, and are dispersed into multiple sub-beams, and the multiple sub-beams are irradiated to different areas of the switching engine 30 respectively.

FIG. 7 is a schematic diagram of an optical path in a first plane of a wavelength selective switch provided by an embodiment of the present application.

Referring to FIG. 7 , the wavelength selective switch 100 further includes 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 The multiplexed light can be irradiated to the dispersion element 20 in a direction parallel to the second plane (y-z plane), that is, the input multiplexed light can be irradiated to the dispersion element 20 in a direction parallel to the second plane through the first lens group 40 on element 20. For example, the first lens group 40 may include multiple lenses. In the first plane, after the multiplexed light input from the input port 11 passes through one or several lenses of the first lens group 40, the multiplexed light may be parallel to the first lens group 40. The light is irradiated onto the dispersion element 20 in the direction of the second plane.

In the first plane, the first lens group 40 can also illuminate the sub-beams emitted from the dispersion element 20 onto the switching engine 30, so that the switching engine 30 can control each sub-beam individually.

FIG. 8 is a schematic diagram of a light spot formed on a switching engine in a wavelength selective switch provided by an embodiment of the present application.

Specifically, the plurality of sub-beams dispersed by the dispersion element 20 are irradiated to different areas of the switching engine 30 through the first lens group 40, and form light spots on the switching engine 30 (see FIG. 8). The switching engine 30 can realize separate processing of sub-beams of each wavelength in different areas, that is, it can independently control the sub-beams of different wavelengths, where the control of the sub-beams can include optical signal switching, optical signal attenuation and optical signal Block etc.

In the first plane (x-z), the switching engine 30 can change the transmission angle of the sub-beams corresponding to different areas, so that the multiple sub-beams are deflected according to preset angles and emitted to form deflected sub-beams, and the deflected sub-beams return along the original path. , passes through the first lens group 40 and the dispersion element 20 and then is irradiated to the output port 12 for output. In this way, by making the deflection angles of the sub-beams different, the deflected sub-beams they form can be irradiated to different output ports. For example, if the deflection angles of the sub-beams of one wavelength are different from those of other sub-beams, the deflection angle of the sub-beams of that wavelength can be different. The sub-beams are output from the corresponding output port 12, thereby realizing the separated output of the wavelength signal, thereby realizing the scheduling and distribution of the signal wavelength.

Since the multiplexed light input from the input port 11 can be irradiated onto the dispersion element 20 in a direction parallel to the second plane through the first lens group 40, this can reduce or eliminate the recombination in the switching plane (first plane). The inclined incident angle between the light and the dispersive element 20 reduces or avoids the difference in the incident angle of each sub-beam in the multiplexed light on the dispersive element 20, thereby significantly reducing the cone diffraction effect of the dispersive element 20 and improving The shape of the light spot is reduced or avoided The absence of sub-beams during channel switching significantly improves the filter passband performance of the wavelength selective switch 100 . Referring to FIG. 8 , the light spot on the switching engine 30 may be the standard Gaussian light spot in FIG. 8 .

In addition, it also helps to reduce the difference in the incident angle of each deflected sub-beam on the dispersive element 20 when the deflected sub-beams return and pass through the dispersive element 20, which helps to reduce the insertion loss of the wavelength selective switch 100 and further improve the wavelength selective switch. 100% performance.

Among them, as shown in Figure 7, 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). 12 can form an input-output port group 10, that is, an input-output port group 10 includes an input port 11 and multiple output ports 12.

The wavelength selective switch 100 may include multiple input and output port groups 10, and the multiple input and output port groups 10 may be stacked in the first plane. The input and output port groups 10 can also be arranged in an array, and each array can include one or more input and output port groups 10 . This can realize the integration of multiple optical signals, so that multiple beams of multiplexed light can be input into the wavelength selective switch at the same time, thus helping to reduce the cost of the entire transmission system.

The input and output port group 10 may include an optical fiber array, and the optical fiber array may include multiple optical fibers. The multiple optical fibers are respectively used for the input port 11 and the output port 12 having the above shapes.

The input and output port group 10 may also include other optical devices that facilitate optical signal transmission, for example, it may also include a collimating lens array.

Among them, in each input and output port group 10, the input port 11 and the output port 12 can be stacked in various ways. For example, multiple output ports 12 can be located on one side of the input port 11, or some of the output ports 12 may be located on one side of the input port 11 , and part of the output port 12 may be located on the other side of the input port 11 .

In each input/output port group 10, the input port 11 and the output port 12, and the output port 12 and the output port 12 can be arranged at intervals. Specifically, the interval distances can be equal.

Continuing to refer to FIG. 7 , specifically, the first lens group 40 may include a first lens 41 , a second lens 42 , a third lens 43 and a fourth lens 44 , and the dispersion element 20 may be located at the second lens 42 and the third lens 44 . on the optical path between lenses 43. The first lens 41 , the second lens 42 , the third lens 43 and the fourth lens 44 may be cylindrical lenses. Of course, in some other examples, the first lens 41 , the second lens 42 , the third lens 43 and the fourth lens 44 Lenses of other shapes are also possible.

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

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. In the x-z plane (first plane), the light beam passes through the second lens 42, the third lens 43 and the third lens 44. When using four lenses 44, the propagation direction of the light beam will change. In the y-z plane (second plane), when the light beam passes through the second lens 42, the third lens 43 and the fourth lens 44, the propagation direction of the light beam remains unchanged.

Specifically, in the first plane (xz plane), the multiplexed light input from the input port 11 is refracted by the first lens 41 and then irradiated onto the second lens 42 . The second lens 42 refracts the multiplexed light that has passed through the first lens 41 so that the multiplexed light irradiates to the dispersion element 20 in a direction parallel to the second plane, thereby reducing the dispersion element of each sub-beam in the multiplexing light. The difference in incident angle on the dispersion element 20 achieves the purpose of eliminating the cone diffraction effect of the dispersion element 20 .

The sub-beam dispersed by the dispersion element 20 is refracted by the third lens 43 and then irradiated to the fourth lens 44. The fourth lens 44 refracts it again, so that the sub-beam is irradiated to the switching engine 30 in a direction parallel to the second plane, thereby This facilitates the switching engine 30 to deflect the sub-beam to form a deflected sub-beam, and ensures that the switching engine 30 controls the sub-beam.

It should be understood that when there are multiple input-output port groups 10 , the multiple input-output port groups 10 can correspond to one first lens group 40 and dispersion element 20 , that is, the inputs from the multiple input-output port groups 10 Multiple beams of multiplexed light entering the wavelength selective switch 100 through the port 11 pass through the same first lens group 40 and the dispersion element 20 and then illuminate different areas of the switching engine 30 .

FIG. 9 is a schematic diagram of an optical path in a first plane of another wavelength selective switch provided by an embodiment of the present application.

Referring to FIG. 9 , the back focal plane of the first lens 41 may coincide with the front focal plane of the second lens 42 , the back focal plane of the second lens 42 may coincide with the dispersion element 20 , and the front focal plane of the third lens 43 may overlap with the dispersion element 20 . The surface may be coincident with the dispersion element 20 , and the back focal plane of the third lens 43 may be coincident with the front focal plane of the fourth lens 44 .

Then, in the first lens group 40, the distance between the front focal plane of the first lens 41 and the back focal plane 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 and focal length of the third lens 43, and f4 is the focal length of the fourth lens 44.

Among them, 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. If they are all f, then the first lens group 40 is 8f. Optical system. The first lens group 40 can play a relay role. Specifically, the relay role means that the light beam passing through the lens group maintains its original optical characteristics (such as the size of the light beam, propagation direction, etc.). The front focal surface of the first lens 41 The spot size is consistent with the spot size on the back focal plane of the fourth lens 44, so that the spot size can be controlled through the first lens group 40, which helps to improve the filter passband performance of the wavelength selective switch 100.

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 may also 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 may be equal, and the focal lengths of some of the lenses may be different.

The dispersive element 20 can be located in the middle of the second lens 42 and the third lens 43 so that the multiplexed light can be irradiated to the dispersive element 20 in a direction parallel to the second plane, thereby reducing the cone diffraction effect, thereby improving the switching engine 30 The light spot shape improves the filter passband performance of the wavelength selective switch 100.

It should be noted that in the embodiment of the present application, the lens may be a single lens element, that is, the first lens group 40 may include four lens elements to achieve the optical path requirements of the first lens group 40 . Alternatively, the lens can also be composed of two or more lens elements, which can be equivalent to one lens on 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 composed of two The lens elements are equivalent, and the two lens elements can achieve the optical path effect of the first lens 41 . Alternatively, the two lenses can share one or more lens elements, as long as they 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. Become. The second lens 42 can also be made up of two equivalent lens elements. The first lens 41 and the second lens 42 can share one lens element. For example, the second lens 42 can be made up of the second lens 42 element and the third lens 43 element. It suffices that the optical path effect of the first lens 41 and the second lens 42 can be achieved.

Figure 10 is a schematic diagram of an optical path for channel switching of a wavelength selective switch provided by an embodiment of the present application.

As shown in FIG. 10 , the wavelength selective switch 100 may further include a switching lens group 50 , and the switching lens group 50 may be located on the optical path between the input port 11 and the first lens group 40 . In the first plane (xz plane), switch the lens The group 50 can perform beam expansion processing on the multiplexed light, and enable the multiplexed light after the beam expansion process to illuminate the first lens group 40 along a direction parallel to the second plane.

That is to say, in the first plane, the multiplexed light input from the input port 11 passes through the switching lens group 50. The switching lens group 50 can expand the beam of the multiplexed light, so that the multiplexed light is parallel to the first plane. The directions of the two planes illuminate the first lens group 40 , specifically, the first lens 41 of the first lens group 40 . The switching lens group 50 can amplify the light spot in the first plane, increase the light spot area, realize the control of the light spot, and help improve the performance of the wavelength selective switch.

The multiplexed light passes through the first lens 41 and the second lens 42 in sequence and is irradiated to the dispersion element 20. The dispersion element 20 disperses the multiplexed light into multiple sub-beams in the second plane. The multiple sub-beams pass through the third lens 43 and the fourth lens in sequence. The lens 44 then illuminates the switching engine 30. The switching engine 30 can deflect multiple sub-beams according to preset angles in the first plane to form deflected sub-beams. The deflected sub-beams return along the original path and pass through the fourth lens 44 and the third lens in sequence. 43. The dispersion element 20, the second lens 42, and the first lens 41 then illuminate the switching lens group 50. The switching lens group 50 can also refract the above-mentioned deflected sub-beams to the corresponding output ports 12, thereby achieving scheduling and distribution of signal wavelengths.

Specifically, the switching lens may include a fifth lens 51. The fifth lens 51 may also be a cylindrical lens. The curved surface of the fifth lens 51 is located in the first plane (x-z plane). For the lens passing through the fifth lens 51 along the z direction, Light beam, the cross section of the fifth lens 51 in the y-z plane is a flat surface, and the cross section in the x-z plane is a curved surface. In the x-z plane (first plane), when the light beam passes through the fifth lens 51, the fifth lens 51 will It refracts the light beam and changes the propagation direction of the light beam. However, in the y-z plane (second plane), when the light beam passes through the fifth lens 51, the propagation direction of the light beam remains unchanged.

That is, in the embodiment of the present application, as shown in FIG. 10 , in the first plane, the multiplexed light input from the input port 11 is irradiated onto the fifth lens 51 (the solid line in FIG. 10 indicates the switching from the input port 11 to The light path of the engine 30), after being expanded by the fifth lens 51, 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, it is parallel to the second plane. The dispersion element 20 is illuminated in a plane direction, and the dispersion element 20 disperses the multiplexed light and emits multiple sub-beams. The multiple sub-beams pass through the third lens 43 and the fourth lens 44 in sequence and then illuminate the switching engine in a direction parallel to the second plane. 30, the switching engine 30 deflects and emits multiple sub-beams according to preset angles to form deflected sub-beams.

After the deflected sub-beam passes through the fourth lens 44, the third lens 43, the dispersion element 20, the second lens 42 and the first lens 41 in sequence (the dotted line in Figure 10 indicates the optical path from the switching engine 30 to the output port 12), it is illuminated to On the fifth lens 51, the deflected sub-beam is refracted, thereby irradiating the deflected sub-beam to the output end. It should be understood that when the deflection angles of at least one wavelength of the deflected sub-beams after passing through the switching engine 30 are different from those of other wavelength sub-beams, they pass through the first lens group 40 and the dispersion element 20 and then are illuminated to the fifth lens 51 The incident angles are also different, and correspondingly, the exit angles are also different, so that the separated light beam and other light beams can be refracted to different output ports 12 for output, thereby realizing the scheduling and distribution of signal wavelengths.

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

Correspondingly, the fifth lens 51 can be a single lens element, or the fifth lens 51 can also be composed of two or more lens elements, which can be equivalent to one lens on the optical path to realize the optical path of the fifth lens 51 Effect.

In the embodiment of the present application, as shown in FIG. 11 , the wavelength selective switch further includes a second lens group 60 . In the 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 to the dispersive element in a direction parallel to the first plane (xz plane). 20 on.

The second lens group 60 can also separately converge the sub-beams dispersed by the dispersive element 20 and irradiate them to the switching engine 30 . That is, after the multiple sub-beams emitted from the dispersive element 20 pass through the second lens group 60 , they can be respectively converged to the switching engine 30 . In different areas of the engine 30, the light spot can also be controlled through the second lens group.

Specifically, as shown in FIG. 11 , the second lens group 60 may include a sixth lens 61 and a seventh lens 62 , and the dispersion element 20 may be located on the optical path between the sixth lens 61 and the seventh lens 62 .

The sixth lens 61 and the seventh lens 62 may be cylindrical lenses, and the curved surface of the sixth lens 61 is located in the second plane. That is, for the light beam passing through the sixth lens 61 along the z direction, the sixth lens 61 is located in the x-z plane. The cross section of is a plane, while 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 sixth lens 61, the sixth lens 61 will refract the light beam, and the propagation of the light beam The direction changes, but in the x-z plane (first plane), when the light beam passes through the sixth lens 61, the propagation direction of the light beam remains unchanged.

The corresponding curved surface of the seventh lens 62 is also located in the second plane. In the y-z plane (second plane), when the light beam passes through the seventh lens 62, the propagation direction of the light beam changes, while in the x-z plane (first plane) , when the light beam passes through the seventh lens 62, the propagation direction of the light beam remains unchanged.

Specifically, in the second plane (y-z plane), the multiplexed light passes through the sixth lens 61. After the sixth lens 61 performs beam expansion processing on the multiplexed light, the multiplexed light is illuminated in a direction parallel to the first plane. On the dispersion element 20, that is, through the sixth lens 61, the multiplexed light beam is expanded, thereby increasing the light spot area.

The seventh lens 62 can separately converge each sub-beam dispersed by the dispersion element 20, so that the multiple sub-beams are respectively irradiated on different areas of the switching engine 30, so that the switching engine 30 can independently process the beams of each wavelength and realize the signal wavelength. scheduling and distribution.

Continuing to refer to FIG. 11 , the back focal plane of the sixth lens 61 may coincide with the dispersion element 20 , and the front focal plane of the seventh lens 62 may also coincide with the dispersion element 20 . Then, in the second lens group 60, the distance between the front focal plane of the sixth lens 61 and the back focal plane of the seventh lens 62 is: f6+f6+f7+f7, where f6 is the focal length of the sixth lens 61. , f7 is the focal length of the seventh lens 62 .

Among them, the focal length f6 of the sixth lens 61 and the focal length f7 of the seventh lens 62 can be equal to each other. If both are f, the second lens group 60 is a 4f optical system, and the second lens group 60 can also play a relay role. , to achieve control of the light path and light spot.

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 may not be equal.

Correspondingly, the sixth lens 61 and the seventh lens 62 can also be a single lens respectively, or the sixth lens 61 and the seventh lens 62 can also be composed of two or more lens elements respectively, and can be equal on the optical path. The sixth lens 61 and the seventh lens 62 are effective. The sixth lens 61 and the seventh lens 62 may also share one or more lens elements, as long as they can achieve the optical path effects of the sixth lens 61 and the seventh lens 62 respectively.

Continuing to refer to Figure 11, the wavelength selective switch 100 also includes a third lens group 70. The third lens group 70 can be located on the optical path between the input port 11 and the second lens group 60, in the second plane (y-z plane), The third lens group 70 can irradiate the multiplexed light input from the input port 11 to the second lens group 60 .

That is, the multiplexed light input from the input port 11 passes through the third lens group 70 and then irradiates the second lens group 60 , specifically, irradiates the sixth lens 61 of the second lens group 60 . The third lens 43 can also adjust the optical path and spot size of the multiplexed light. Play a regulatory role.

Specifically, as shown in FIG. 11 , the third lens group 70 may include an eighth lens 71 and a ninth lens 72 . The eighth lens 71 may be located on the optical path between the input port 11 and the ninth lens 72 . The eighth lens 71 And the ninth lens 72 may be a cylindrical lens.

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 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 changes, while in the x-z plane (first plane) , when the light beam passes through the eighth lens 71, the propagation direction of the light beam remains unchanged.

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

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 perform beam expansion processing on the multiplexed light, so that the multiplexed light is parallel to the first lens 71. A plane direction illuminates the ninth lens 72 .

The ninth lens 72 can condense the multiplexed light and illuminate it on the second lens group 60 , specifically, on the sixth lens 61 . The multiplexed light is expanded through the eighth lens 71 and then converged through the ninth lens 72 . In this way, the light spot is controlled through the third lens group 70 and the phenomenon of the light spot increasing with the transmission of the multiplexed light is reduced.

Continuing to refer to FIG. 11 , the back focal plane of the eighth lens 71 can coincide with the front focal plane of the ninth lens 72 (the dotted line part in FIG. 11 is the overlapping part), then in the third lens group 70 , the eighth lens 71 The distance from the front focal plane to the back focal plane 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.

Among them, the focal length f8 of the eighth lens 71 and the focal length f9 of the ninth lens 72 can be equal. If both are f, the third lens group 70 is a 4f optical system, and the third lens group can also play a relay role to achieve alignment. For the control of light path and light spot, the light spot on the front focal surface of the eighth lens is consistent with the light spot on the rear focal surface of the ninth lens.

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 may not be equal.

Correspondingly, the eighth lens 71 and the ninth lens 72 can also be a single lens respectively, or the eighth lens 71 and the ninth lens 72 can also be composed of two or more lens elements respectively, and can be equal on the optical path. The eighth lens 71 and the ninth lens 72 are effective. Among them, the eighth lens 71 and the ninth lens 72 can also share one or more lens elements, as long as they can achieve the optical path effects of the eighth lens 71 and the ninth lens 72 respectively.

It should be noted that when the switching engine 30 is a polarization-related channel switching device, for example, when the switching engine is a 30-bit silicon-based liquid crystal chip, the wavelength selective switch 100 may also include a polarizing optical element (not shown in the figure) , specifically, the polarizing optical element can be located between the third lens group 70 and the second lens group 60 , or the polarizing optical element can be located in the third lens group 70 , specifically, located in the eighth lens 71 and the ninth lens 72 between. The polarization optical element can realize polarization adjustment, thereby facilitating the switching engine 30 to implement channel switching.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present application, but not to limit them; although the embodiments of the present application have been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art It should be understood that the technical solutions recorded in the foregoing embodiments can still be modified, or the technical solutions described in the foregoing embodiments can still be modified. Some or all of the technical features are equivalently substituted; and these modifications or substitutions do not cause the essence of the corresponding technical solution to depart from the scope of the technical solution of each embodiment of the present application.

Claims

A wavelength selective switch, characterized in that it includes an input and output port group, the input and output port group includes an input port and a plurality of output ports that are stacked in a first plane, and the input port is used to input multiplexed light, The multiplexed light includes a plurality of sub-beams of different wavelengths;

It also includes a dispersion element and a switching engine. The dispersion element is configured to disperse the multiplexed light input from the input port into a plurality of sub-beams in a second plane, and convert the plurality of sub-beams into Illuminating different areas of the switching engine respectively, and the first plane and the second plane are orthogonal;

It also includes a first lens group, the dispersion element is located in the first lens group in the first plane, and the first lens group is configured to direct the multiplexed light along parallel lines in the first plane. The direction of the second plane illuminates the dispersion element, and the first lens group is further configured to illuminate the sub-beam emitted from the dispersion element in the first plane to the switching engine;

The switching engine is configured to emit a plurality of the sub-beams according to a preset deflection angle in a first plane to form deflected sub-beams, and cause the deflected sub-beams to pass through the first lens group, the dispersion The component is output from the corresponding output port.
The wavelength selective switch according to claim 1, wherein 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 fourth lens. between the third lens;

The first lens is configured to illuminate the multiplexed light onto the second lens in a 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 a first plane;

The third lens is configured to illuminate the sub-beam dispersed by the dispersion element onto the fourth lens in a first plane;

The fourth lens is configured to illuminate the sub-beam passing through the third lens onto the switching engine in a first plane in a direction parallel to the second plane.
The wavelength selective switch according to claim 2, wherein the back focal plane of the first lens coincides with the front focal plane of the second lens, and the back focal plane of the second lens coincides with the dispersion element. coincide;

The front focal plane of the third lens coincides with the dispersion element, and the back focal plane of the third lens coincides with the front focal plane of the fourth lens.
The wavelength selective switch according to claim 2 or 3, characterized in that 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. .
The wavelength selective switch according to any one of claims 2 to 4, wherein the dispersion element is located between the second lens and the third lens.
The wavelength selective switch according to any one of claims 1 to 5, further comprising a switching lens group configured to expand the multiplexed light beam in the first plane and then make it along the Illuminating the first lens group in a direction parallel to the second plane;

The switching lens group is further configured to refract the deflected sub-beam after passing through the first lens group and the dispersion element to the corresponding output port in the first plane.
The wavelength selective switch according to claim 6, wherein the switching lens group includes a fifth lens, and the curved surface of the fifth lens is located on the first plane.
The wavelength selective switch according to any one of claims 1 to 7, further comprising a second lens group, the dispersion element is located in the second lens group in the second 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 dispersion element in the second plane The dispersed sub-beams are irradiated onto the switching engine.
The wavelength selective switch according to claim 8, wherein the second lens group includes a sixth lens and a seventh lens;

The sixth lens is configured to expand the multiplexed light in the second plane and then illuminate the dispersion element;

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 respectively illuminate different areas of the switching engine.
The wavelength selective switch according to claim 9, 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.
The wavelength selective switch according to claim 10, wherein the focal length of the sixth lens is equal to the focal length of the seventh lens.
The wavelength selective switch according to any one of claims 8-11, further comprising a third lens group configured in a second plane to illuminate the multiplexed light to the third lens group. Two lens group.
The wavelength selective switch according to claim 12, wherein the third lens group includes an eighth lens and a ninth lens, and the eighth lens is configured to expand the multiplexed light in the second plane. After the beam is beamed, it is irradiated to the ninth lens;

The ninth lens is configured to converge and illuminate the multiplexed light passing through the eighth lens to the second lens group in the second plane.
The wavelength selective switch according to claim 13, wherein the back focal plane of the eighth lens coincides with the front focal plane of the ninth lens.
The wavelength selective switch according to any one of claims 1 to 14, characterized in that the number of the input and output port groups is multiple;

A plurality of the input and output port groups are stacked in the first plane.
The wavelength selective switch according to any one of claims 1 to 15, characterized in that the dispersion element includes a grating or a prism.