WSS, ROADM, and optical switching system

Abstract

The invention provides a WSS, an ROADM and an optical switching system, which are applied to the field of optical communication. In a WSS, M input ports are used to receive M first light beams. The first grating is used for splitting each first light beam into P sub-light beams to obtain M * P sub-light beams. The first-stage switching engine is used for applying a switching angle to the M * P sub-beams. In a height plane, the second grating, the lens group and the third grating are used for realizing port switching of light beams. In the dispersion plane, the second grating, the lens group and the third grating are used for imaging the M * P sub-beams output by the first-stage switching engine to the second-stage switching engine. And the second-stage switching engine is used for adjusting the output angle of the M * P sub-beams. According to the invention, the optical gratings are used for carrying out wave combination and wave separation on the light beams, so that the size of a lens between the optical gratings can be reduced, and the size of the WSS is reduced.

Description

Technical Field

[0001] The present application relates to the field of optical communications, and in particular to a wavelength selective switch (WSS), a reconfigurable optical add / drop multiplexer (ROADM) and an optical switching system. Background Art

[0002] Backbone and metropolitan transport networks build ROADM based on WSS, which can flexibly schedule wavelengths and achieve efficient use of wavelength resources. WSS includes an input port, a first-level switching engine, an intermediate lens group, a second-level switching engine, and an output port. The first imaging optical path is between the input port and the first-level switching engine. The first imaging optical path is used to image the incident light beam to the first-level switching engine. On the height plane, the intermediate lens group is used to convert the exit angle characteristics of the output light beam of the first-level switching engine into the incident position characteristics of the second-level switching engine. On the dispersion plane, the intermediate lens group is used to image the output light beam of the first-level switching engine to the second-level switching engine. The second imaging optical path is between the second-level switching engine and the output port. The second imaging optical path is used to image the output light beam of the second-level switching engine to the output port. In practical applications, the size of the intermediate lens group is large, which leads to a large size of the WSS. Summary of the invention

[0003] The present application provides a WSS, ROADM and optical switching system, which can reduce the size of lens groups between gratings by using gratings to combine and split light beams, thereby reducing the size of the WSS.

[0004] The first aspect of the present application provides a WSS. The WSS includes M input ports, a first grating, a first-level switching engine, a second grating, a lens group, a third grating, a second-level switching engine, a fourth grating and N output ports. The M input ports are used to receive M first light beams and transmit the M first light beams to the first grating. The M first light beams correspond to the M input ports one by one. M is an integer greater than 1. The first grating is used to split each of the M first light beams into P sub-beams to obtain M×P sub-beams. P is an integer greater than 1. The first grating is used to transmit the M×P sub-beams to the first-level switching engine. The first-level switching engine is used to apply a switching angle to the M×P sub-beams. The second grating, the lens group and the third grating are located between the first-level switching engine and the second-level switching engine. At least one lens in the lens group is located between the second grating and the third grating. In the height plane, the second grating, the lens group and the third grating are used to convert the exit angle characteristics of the output light beam of the first-level switching engine into the incident position characteristics of the second-level switching engine. In the dispersion plane, the second grating is used to combine the M×P sub-beams after the switching angle to obtain multiple target beams. The third grating is used to split the multiple target beams to obtain the M×P sub-beams after the switching angle. The second grating, the lens group and the third grating are used to image the M×P sub-beams after the switching angle output by the first-level switching engine to the second-level switching engine. The second-level switching engine is used to receive the M×P sub-beams after the switching angle, adjust the output angle of the M×P sub-beams after the switching angle, and transmit the M×P sub-beams after the adjusted output angle to the fourth grating. The fourth grating is used to combine the M×P sub-beams after the output angle is adjusted to obtain N second beams. The N output ports are used to output the N second beams. N is an integer greater than 1. The N second beams correspond to the N output ports one by one.

[0005] In an optional manner of the first aspect, the first grating, the second grating and the third grating are the same grating. The first grating includes a first area and a second area. The first grating is used to split each of the M first beams into P sub-beams, and the M×P sub-beams are obtained, including: the first area of ​​the first grating is used to split each of the M first beams into P sub-beams, and the M×P sub-beams are obtained. In the height plane, the second grating, the lens group and the third grating are used to implement the port switching of the beam, including: the lens group and the second area of ​​the first grating are used to implement the port switching of the beam. In the dispersion plane, the second grating, the lens group and the third grating are used to image the M×P sub-beams after the switching angle output by the first-level switching engine to the second-level switching engine, including: the lens group and the second area of ​​the first grating are used to image the M×P sub-beams after the switching angle output by the first-level switching engine to the second-level switching engine. The deflection angle applied by the first area of ​​the first grating to the M first beams is different from the deflection angle applied by the second area of ​​the first grating to the M×P sub-beams. By using the same grating, the number of optical elements in the WSS can be reduced, thereby reducing the size of the WSS.

[0006] In an optional manner of the first aspect, the grating density of the first region is different from the grating density of the second region.

[0007] In an optional manner of the first aspect, the grating plane of the first region is different from the grating plane of the second region, or the prism plane of the first region is different from the prism plane of the second region.

[0008] In an optional manner of the first aspect, the second region of the first grating is integrated with a lens function. By integrating the lens function on the grating, the number of lenses in the lens group can be reduced, thereby reducing the size of the WSS.

[0009] In an optional manner of the first aspect, the second region realizes a lens function through non-periodic grooves. In the present application, the first region and the second region are located on the same grating. The lens function is realized through non-periodic grooves, and the lens function can be realized without adding additional elements.

[0010] In an optional manner of the first aspect, the lens group includes a first lens, a second lens, and a third lens. The second grating is located on the light transmission path of the first lens and the second lens. The third grating is located on the light transmission path between the second lens and the third lens. The focal length of the second lens on the height plane is different from the focal length of the second lens on the dispersion plane.

[0011] In an optional manner of the first aspect, the lens group is a 2F optical path or an odd multiple of 2F optical path on the height plane. The lens group is a 4F optical path or an integer multiple of 4F optical path on the dispersion plane.

[0012] In an optional manner of the first aspect, the second grating is a reflective grating, and the first lens and the third lens are the same lens. By using a reflective switching engine, the first lens and the third lens can be the same lens, thereby reducing the number of optical elements in the WSS and reducing the size of the WSS.

[0013] In an optional manner of the first aspect, the second region is integrated with a lens function on the dispersion plane. The focal length of the second region on the dispersion plane is F. The second region is not integrated with a lens function on the height plane. The distance between the second grating and the third grating is 2F. The focal length of the second lens on the height plane is F. The focal length of the second lens on the dispersion plane is F / 2.

[0014] In an optional manner of the first aspect, the second region is integrated with a lens function on the height plane. The focal length of the second region on the height plane is F. The second region has no integrated lens function on the dispersion plane. The distance between the second grating and the third grating is 3F. The second lens includes a first spherical lens, a first cylindrical lens, and a second spherical lens. The focal length of the first spherical lens and the second spherical lens is F / 2. The focal length of the first cylindrical lens on the height plane is infinite. The focal length of the first cylindrical lens on the dispersion plane is -F / 4.

[0015] In an optional manner of the first aspect, the first cylindrical lens is a reflective lens, and the first spherical lens and the second spherical lens are the same spherical lens. By using a reflective lens, the number of optical elements in the WSS can be reduced, thereby reducing the size of the WSS.

[0016] A second aspect of the present application provides a ROADM. The ROADM includes one or more WSSs described in the first aspect or any optional manner of the first aspect.

[0017] The third aspect of the present application provides an optical switching system, which includes the ROADM described in the second aspect and another ROADM, wherein the ROADM is used to transmit a second light beam to the another ROADM. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The first optical path principle diagram of the WSS provided in the embodiment of the present application;

[0019] Figure 2 A second optical path schematic diagram of the WSS provided in an embodiment of the present application;

[0020] Figure 3 A third optical path schematic diagram of the WSS provided in an embodiment of the present application;

[0021] Figure 4 The fourth optical path principle diagram of the WSS provided in the embodiment of the present application;

[0022] Figure 5 The fifth optical path principle diagram of the WSS provided in the embodiment of the present application;

[0023] Figure 6 A first structural diagram of the WSS provided in the embodiment of the present application;

[0024] Figure 7 A second structural diagram of the WSS provided in the embodiment of the present application;

[0025] Figure 8 A schematic diagram of the structure of a first grating provided in an embodiment of the present application;

[0026] Fig. 9 A first structural schematic diagram of an optical switching node provided in an embodiment of the present application;

[0027] Fig.10 A second structural schematic diagram of an optical switching node provided in an embodiment of the present application;

[0028] Fig.11 This is a schematic diagram of the structure of the optical communication system provided in this application. DETAILED DESCRIPTION

[0029] The present application provides a WSS, ROADM and optical switching system. By using gratings to combine and split light beams, the size of the lens group between the gratings can be reduced, thereby reducing the size of the WSS. It should be understood that the "first", "second", "target", etc. used in the present application are only used for the purpose of distinguishing the description, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying an order. In addition, for the sake of simplicity and clarity, reference numbers and / or letters are repeated in multiple figures of the present application. Repetition does not indicate a strict limiting relationship between various embodiments and / or configurations.

[0030] Some professional terms appearing in the embodiments of the present application are explained below:

[0031] Dispersion plane: A grating can disperse a beam of light containing multiple wavelengths. The direction in which the light is dispersed is called the dispersion direction. The plane where the multiple wavelengths of light are located after the light is dispersed is called the dispersion plane. The first imaging optical path of WSS includes a grating for dispersing the first light beam.

[0032] Height plane: The plane perpendicular to the dispersion plane.

[0033] 4F optical path: 4F optical path is the basic optical path in optics. Assuming that the focal length F of two lenses is the same, the two lenses are arranged on the same optical axis and the distance between them is 2F, the object plane is placed at a distance F before the combined lens, and the imaging plane is placed at a distance F after the combined lens, then a total length of 4F optical path is formed, which is called 4F optical path. 4F optical path can achieve 1:1 imaging from the object plane to the imaging plane.

[0034] 2F optical path: For a single lens with a focal length of F. When the object plane is at a distance F in front of the lens and the image plane is at a distance F behind the lens, the optical path with a total length of 2F can convert the switching angle difference of the object plane into the position difference of the image plane, which is also called the switching optical path.

[0035] Polarization-dependent LCoS (liquid crystal on silicon), polarization-independent LCoS: LCoS achieves beam deflection by applying phase modulation to the beam. LCoS that can only modulate a single polarization state beam or LCoS that modulates orthogonal polarization states with inconsistent phases is called polarization-dependent LCoS. LCoS that can modulate beams of any polarization state is called polarization-independent LCoS.

[0036] The WSS provided in the present application is applied to the field of optical communication. In the field of optical communication, an optical switching system, such as a backbone transmission network and a metropolitan area transmission network, can be constructed by using a ROADM including a WSS. The WSS includes a plurality of lenses and a switching engine. The switching engine is used to apply a deflection angle to the light beam. The lens is used to achieve light beam transformation and light angle change, etc. Therefore, the size of the lens will affect the size of the WSS. In practical applications, the size of the lens is large and the number is large, which leads to a large size of the WSS.

[0037] To this end, an embodiment of the present application provides a WSS. Figure 1 The first optical path principle diagram of the WSS provided in the embodiment of the present application. Figure 1 As shown, WSS100 includes M input ports 101, a first imaging optical path 102, a first-stage switching engine 103, an intermediate lens group 104, a second-stage switching engine 105, a second imaging optical path 106, and N output ports 107. The figure shows an input port. The M input ports 101 are used to receive M first light beams with multiple wavelengths. M is an integer greater than 1. The M first light beams correspond to the M input ports one by one. The functions of each optical element in WSS100 are described below on the height plane and the dispersion plane respectively.

[0038] On the height plane, the first imaging optical path 102 is used to image the M first light beams to the first-level switching engine 103. The first-level switching engine 103 can be an LCOS, a liquid crystal (LC) array or a micro electro mechanical system (MEMS). The first-level switching engine 103 is used to apply a corresponding deflection angle to the light beam according to the wavelength of the light beam, that is, the first-level switching engine 103 is used to apply a switching angle to the M×P sub-beams. The intermediate lens group 104 is a switching lens. The intermediate lens group 104 is used to convert the output angle characteristics of the output light beam of the first-level switching engine 103 into the incident position characteristics of the second-level switching engine 105, that is, under ideal conditions, the light beams with different output angles of the first-level switching engine 103 have different incident positions in the second-level switching engine 105, and the light beams with the same output angle in the first-level switching engine 103 have the same incident position in the second-level switching engine 105. In practical applications, due to the errors of optical elements, the light beams with the same output angle in the first-level switching engine 103 may also have different incident positions in the second-level switching engine 105. The second switching engine 105 is used to adjust the output angle of the light beam. The second imaging optical path 106 is used to image the output light beam of the second switching engine 105 to the output port 107. The N output ports 107 are used to output N second light beams. The N second light beams are obtained based on the M first light beams.

[0039] On the dispersion plane, the first imaging optical path 102 is used to split each of the M first optical beams into P sub-beams to obtain M×P sub-beams. The first imaging optical path 102 is used to collimate and transmit the M×P sub-beams to the first-stage switching engine 103. Figure 1 In the example, the first light beam includes three wavelengths. The three wavelengths correspond to Figure 13 solid lines with arrows output from the first imaging optical path 102 in the figure. On the dispersion plane, the intermediate lens group 104 is a relay lens. The intermediate lens group 104 is used to image the output light beam of the first-level switching engine 103 to the second-level switching engine 105. The second imaging optical path 106 is used to combine M×P sub-beams to obtain N second light beams. N output ports 107 are used to output N second light beams. The N output ports 107 correspond one-to-one to the N second light beams. N is an integer greater than 1. It should be understood that on the dispersion plane, the intermediate lens group 104 is used to realize the imaging function without realizing the port switching function. The intermediate lens group 104 can magnify, reduce or invert the image. The WSS100 in the embodiment of the present application does not need to provide a port switching function on the dispersion plane. Therefore, on the dispersion plane, the first-level switching engine 103 can apply a corresponding deflection angle to the light beam without applying a corresponding deflection angle to the light beam according to the wavelength of the light beam. Similarly, the second-level switching engine 105 can adjust the output angle of the light beam without adjusting the output angle of the light beam.

[0040] In the embodiment of the present application, the intermediate lens group 104 includes a second grating, a lens group and a third grating. Figure 2 The second optical path principle diagram of the WSS provided in the embodiment of the present application. Figure 2 As shown, WSS100 includes a first-stage switching engine 103, an intermediate lens group 104 and a second-stage switching engine 105. The intermediate lens group 104 includes a lens group, a second grating 202 and a third grating 204. The lens group includes a first lens 201, a second lens 203 and a third lens 205. The functions of each optical element in the intermediate lens group 104 are described below on the height plane and the dispersion plane.

[0041] On the height plane, the first-level switching engine 103 is used to apply a switching angle to the light beam. For example, the first-level switching engine 103 is used to apply different deflection angles to two wavelength light beams to obtain two light beams with different output angles (one is represented by a solid line with an arrow, and the other is represented by a dotted line to be arrowed). The focal length of the first lens 201, the second lens 203, and the third lens 205 is F. In subsequent examples, unless otherwise specified, the focal length of the lens is F. The distance between two adjacent lenses in the lens group is 2F. The second grating 202 is on the light transmission path between the first lens 201 and the second lens 203. The third grating 204 is on the light transmission path between the second lens 203 and the third lens 205. The grating can be a diffraction grating, an arrayed waveguide grating (AWG), etc., which is not limited in this application. At this time, the lenses in the lens group form a 6F optical path (an odd multiple of 2F). The middle lens group 104 is used to convert the emission angle characteristics of the output light beam of the first-stage switching engine 103 into the incident position characteristics of the second-stage switching engine 105. The second-stage switching engine 105 is used to adjust the output angle of the light beam.

[0042] On the dispersion plane, the first-stage switching engine 103 is used to output M×P sub-beams after the switching angle. Figure 2 In the example, the first-stage switching engine 103 is used to output two sub-beams. The two sub-beams include two beams of different wavelengths (one represented by a solid line with an arrow, and the other represented by a dotted line with an arrow). For the description of the distance between the various optical elements in the intermediate lens group 104, reference can be made to the aforementioned description of the intermediate lens group 104 on the height plane. The focal lengths of the first lens 201 and the third lens 205 are F. The focal length of the second lens 203 is F / 2. The distance between two adjacent lenses in the lens group is 2F. The second grating 202 and the third grating 204 are integrated with lens functions. The focal lengths of the second grating 202 and the third grating 204 are F. The second lens 203 is located at the image focus of the second grating 202 and at the object focus of the third grating 204. The distance between the second grating 202 and the third grating 204 on the optical path schematic diagram is 2F. At this time, the lenses and gratings in the intermediate lens group 104 form a deformed optical path of the 4F optical path. The deformed optical path is equivalent to the optical path obtained by splicing two 4F optical paths. The intermediate lens group 104 is used to image the output light beam of the first-stage switching engine 103 to the second-stage switching engine 105. In addition to the lens function, the second grating 202 and the third grating 204 also have the function of combining and splitting waves. Specifically, the second grating 202 is used to combine the M×P sub-beams after the switching angle output by the first lens 201 to obtain multiple target beams. The third grating 204 is used to split the multiple target beams output by the second lens 203 to obtain M×P sub-beams after the switching angle.

[0043] In the embodiment of the present application, by using a grating to combine and split the light beams, the size of the lenses between the gratings, such as the size of the second lens 203 on the dispersion plane, can be reduced. The size of the second lens 203 will affect the size of the WSS100. Therefore, the embodiment of the present application can reduce the size of the WSS100. In addition, by integrating the lens function on the grating, the number of lenses in the WSS100 can be reduced, thereby further reducing the size of the WSS100.

[0044] In the above example, the second grating 202 and the third grating 204 are integrated with lens functions. It should be understood that in practical applications, those skilled in the art can add corresponding lenses to the WSS 100 to replace the function of integrating the lenses on the gratings. Figure 2 In the example, the distance between the second grating 202 and the second lens 203 is F. A cylindrical lens with a focal length of F / 2 is added between the second grating 202 and the second lens 203. The distance between the cylindrical lens and the second lens 203 is F / 2. Similarly, at a distance F / 2 from the second lens 203, another cylindrical lens is symmetrically arranged between the second grating 204 and the second lens 203. The focal length of the second lens 203 in the dispersion plane is set to be infinite. The focal lengths of the cylindrical lens and the other cylindrical lens in the dispersion plane are F / 2. The focal lengths of the cylindrical lens and the other cylindrical lens in the height plane are infinite.

[0045] In the above Figure 2 In the example of FIG. 2 , the second grating 202 and the third grating 204 are integrated with a lens function on the dispersion plane. In practical applications, the second grating 202 and the third grating 204 can also be integrated with a lens function on the height plane. This is described below. Figure 3 The third optical path principle diagram of the WSS provided in the embodiment of the present application. Figure 3 As shown, WSS100 includes a first-stage switching engine 103, an intermediate lens group 104, and a second-stage switching engine 105. The intermediate lens group 104 includes a lens group, a second grating 202, and a third grating 204. The lens group includes a first lens 201, a second lens 203, and a third lens 205. The second lens 203 includes a first spherical lens 301, a first cylindrical lens 302, and a second spherical lens 303. The functions of each optical element in the intermediate lens group 104 are described below on the height plane and the dispersion plane, respectively.

[0046] In the height plane, the first level switching engine 103 is used to apply a switching angle to the light beam. Figure 3In the example of , the first-stage switching engine 103 is used to apply different deflection angles to two wavelength beams to obtain two beams with different output angles (one is represented by a solid line with an arrow, and the other is represented by a dotted line with an arrow). The distance between the first lens 201 and the second grating 202 is F. The distance between the second grating 202 and the first spherical lens 301 is F. The distance between the first spherical lens 301 and the second spherical lens 303 is F. The distance between the second spherical lens 303 and the third grating 204 is F. The distance between the third grating 204 and the third lens 205 is F. The distance between the first cylindrical lens 302 and the first spherical lens 301 is F / 2. The distance between the first cylindrical lens 302 and the second spherical lens 303 is F / 2. The distance between the second grating 202 and the third grating 204 is 3F. The focal length of the first spherical lens 301 and the second spherical lens 303 is F / 2. The focal length of the first cylindrical lens 302 is infinite. The second grating 202 and the third grating 204 are integrated with lens functions. The focal lengths of the second grating 202 and the third grating 204 are F. At this time, the lenses and gratings in the intermediate lens group 104 form a deformed optical path of the 6F optical path. The intermediate lens group 104 is used to convert the emission angle characteristics of the output light beam of the first-stage switching engine 103 into the incident position characteristics of the second-stage switching engine 105. The second-stage switching engine 105 is used to adjust the output angle of the light beam.

[0047] On the dispersion plane, the first-stage switching engine 103 is used to output M×P sub-beams after the switching angle. Figure 3 In the example, the first-level switching engine 103 is used to output two sub-beams. The two sub-beams include two beams of different wavelengths (one is represented by a solid line with an arrow, and the other is represented by a dotted line with an arrow). For the description of the distances between the various optical elements in the intermediate lens group 104, reference can be made to the aforementioned description of the intermediate lens group 104 on the height plane. The focal length of the first spherical lens 301 and the second spherical lens 303 is F / 2. The focal length of the first cylindrical lens 302 is -F / 4. The second grating 202 and the third grating 204 do not have lens functions integrated therein. The second grating 202 and the third grating 204 have the functions of combining and splitting. The second grating 202 is used to combine the M×P sub-beams after the switching angle output by the first lens 201, and the third grating 204 is used to split the M×P sub-beams after the switching angle output by the second lens 203. At this time, the lenses in the intermediate lens group 104 form a deformed optical path of the 4f optical path, where f=F / 2. The middle lens group 104 is used to image the output light beam of the first-stage switching engine 103 to the second-stage switching engine 105 .

[0048] In practical applications, the first cylindrical lens 302 can be a reflective lens or a transmissive lens. In order to reduce the number of optical elements in the WSS 100, the first cylindrical lens 302 can be a reflective lens. In this case, the first spherical lens and the second spherical lens are the same spherical lens. By reducing the number of optical elements in the WSS 100, the size of the WSS 100 can be reduced.

[0049] according to Figure 1 As can be seen from the description, WSS100 can also include a first imaging optical path and a second imaging optical path. Figure 2 This is described using WSS in as an example. Figure 4 The fourth optical path principle diagram of the WSS provided in the embodiment of the present application. Figure 4 As shown, in Figure 1 On the basis of, the first imaging optical path 102 includes lens 401, first grating 402 and lens 403, and the second imaging optical path 106 includes lens 404, grating 405 and lens 406. The functions of each optical element in the imaging optical path are described below on the height plane and the dispersion plane.

[0050] On the height plane, the first imaging optical path 102 is used to receive M first light beams from M input ports (not shown in the figure). The distance between the lens 401 and the first grating 402 is F. The distance between the lens 403 and the first grating 402 is F. The focal length of the lens 401 and the lens 403 is F. The first grating 402 does not have the function of combining and splitting waves on the height plane. At this time, the lenses (lens 401 and lens 403) in the first imaging optical path 102 form a 4F optical path. The first imaging optical path 102 is used to image the M first light beams to the first-level switching engine 103. For the description of the first-level switching engine 103, the intermediate lens group 104 and the second-level switching engine 105 on the height plane, please refer to the aforementioned Figures 1 to 3 Description of any of the figures in . The distance between lens 404 and grating 405 is F. The distance between lens 405 and grating 406 is F. The focal length of lens 404 and lens 406 is F. Grating 405 does not have the function of combining and splitting waves on the height plane. At this time, the lenses (lens 404 and lens 406) in the second imaging optical path 106 form a 4F optical path. The second imaging optical path 106 is used to image the output light beam of the second-level switching engine 105 to N output ports (not shown in the figure).

[0051] On the dispersion plane, the first grating 402 is used to split each of the M first beams into P sub-beams, thereby obtaining M×P sub-beams. The first grating 402 is used to transmit the M×P sub-beams to the lens 403. The lens 403 is used to collimate the M×P sub-beams and inject them into the first-stage switching engine 103. For the description of the first-stage switching engine 103, the intermediate lens group 104, and the second-stage switching engine 105 on the dispersion plane, reference can be made to the aforementioned Figures 1 to 3 The second imaging optical path 106 is used to receive M×P sub-beams from the second-stage switching engine 105. The lens 404 is used to converge the M×P sub-beams to the fourth grating 405. The fourth grating 405 is used to combine the M×P sub-beams to obtain N second beams. The WSS100 outputs the N second beams through the lens 406.

[0052] In practical applications, the first-stage switching engine 103 and the second-stage switching engine 105 can be polarization-independent LCoS or polarization-dependent LCoS. Figure 4 As shown. The optical path principle diagram of the WSS using polarization-independent LCoS is referred to as the first optical path principle diagram. The optical path principle diagram of the WSS using polarization-dependent LCoS is referred to as the second optical path principle diagram. On the height plane, the second optical path principle diagram is similar to the first optical path principle diagram. The second optical path principle diagram on the dispersion plane is described below. Figure 5 The fifth optical path principle diagram of the WSS provided in the embodiment of the present application. Figure 5 As shown, WSS100 includes a first imaging optical path 102, a first-stage switching engine 103, an intermediate lens group 104, a second-stage switching engine 105, and a second imaging optical path 106. The optical elements included in WSS100 and the distances and focal lengths between the optical elements can be referred to. Figure 4 The functions of the optical components in WSS100 are described below.

[0053] The lens 401 in the first imaging optical path 102 is used to receive two light beams with different polarizations. For example, the lens 401 is used to receive a first polarized light beam 501 and a second polarized light beam 502 whose polarization states are orthogonal. The first polarized light beam 501 and the second polarized light beam 502 are also referred to as first light beams. The optical transmission paths of the first polarized light beam 501 and the second polarized light beam 502 in WSS100 are similar, and the embodiment of the present application only describes the first polarized light beam 501 as an example. The first polarized light beam 501 includes M first light beams (one first light beam is illustrated in the figure). The first grating 402 is used to disperse and expand the first polarized light beam 501 to obtain M×P sub-beams. The first grating 402 is used to transmit the M×P sub-beams to the lens 403. Figure 5In the example, the M×P sub-beams include two beams of different wavelengths. The solid line with an arrow indicates one of the beams, and the dotted line with an arrow indicates the other beam. The lens 403 is used to collimate the M×P sub-beams and incident them on the first-level switching engine 103. The first-level switching engine 103 is used to receive the M×P sub-beams. The first-level switching engine 103 does not need to apply a corresponding deflection angle to the beam according to the wavelength of the beam on the dispersion plane. The intermediate lens group 104 is a relay lens. The intermediate lens group 104 is used to image the output beam of the first-level switching engine 103 to the second-level switching engine 105. The second-level switching engine 105 is used to receive the M×P sub-beams after the switching angle, and transmit the M×P sub-beams after the switching angle to the lens 404. The lens 404 is used to converge the M×P sub-beams after the switching angle to the fourth grating 405. The fourth grating 405 is used to combine the M×P sub-beams after the switching angle to obtain N second beams, and output the N second beams through the lens 406. It should be understood that the description of the first imaging optical path 102, the first-stage switching engine 103, the intermediate lens group 104 and the second-stage switching engine 105 on the dispersion plane can be referred to in the aforementioned Figures 1 to 4 A description of any figure in . Figures 1 to 5 It is a schematic diagram of the optical path of WSS100 provided in an embodiment of the present application.

[0054] In practical applications, the number of optical components in the structural diagram of WSS100 can be reduced through reasonable optical path design. Figure 5 In the embodiment, when the lens 203 is a reflector, the second grating 202 and the third grating 204 can be the same grating. For another example, when the lens 203 is a reflector and the first-stage switching engine 103 is a reflective switching engine, the first-stage switching engine 103 and the second-stage switching engine 105 can be the same switching engine. The structure of the WSS is described exemplarily below.

[0055] Figure 6 The first structural diagram of the WSS provided in the embodiment of the present application. On the height plane, such as Figure 6 As shown, the WSS includes a lens 401 , a first grating 402 , a lens 403 , a first-stage switching engine 103 and a lens 203 . Figure 6Including Figure a, Figure b, and Figure c. As shown in Figure a, the lens 401 is used to receive M first light beams. The first area of ​​the first grating 402 is used to receive M first light beams from the lens 401, and transmit the M first light beams to the lens 403 through the first area. The lens 403 is used to transmit the M first light beams to the first-level switching engine 103. The first-level switching engine 103 is used to apply a switching angle to the light beam. For example, the first-level switching engine 103 is used to apply different deflection angles to two wavelength light beams to obtain two light beams with different output angles (one is represented by a solid line with an arrow, and the other is represented by a dotted line with an arrow). The first-level switching engine 103 is a reflective switching engine. As shown in Figures a and b, the output light beam of the first-level switching engine 103 is transmitted to the second area of ​​the first grating 402 after passing through the lens 403. The diffraction capabilities of the second area of ​​the first grating 402 and the first area of ​​the first grating 402 are different, thereby realizing the separation of the first light beam and the reflected light beam of the first-level switching engine 103, and the reflected light beam of the first-level switching engine 103 will not be reflected back to the lens 401. The second area of ​​the first grating 402 transmits the light beam to the lens 203. The lens 203 is a reflective lens. The lens 203 is used to reflect the light beam to the second area of ​​the first grating 402. As shown in Figure c, the light beam output by the second area of ​​the first grating 402 is transmitted to the first-level switching engine 103 again after passing through the lens 203. The first-level switching engine 103 is used to adjust the output angle of the light beam. The light beam output by the first-level switching engine 103 passes through the lens 203, the first area of ​​the first grating 402 and the lens 201 in sequence.

[0056] Figure 7 The second structural diagram of the WSS provided in the embodiment of the present application. On the dispersion plane, Figure 7 As shown, the WSS includes a lens 401 , a first grating 402 , a lens 403 , a first-stage switching engine 103 and a lens 203 . Figure 7Including Figure d, Figure e and Figure f. As shown in Figure d, the lens 401 is used to receive M first light beams. The first area of ​​the first grating 402 is used to receive M first light beams from the lens 401, and disperse the M first light beams to obtain M×P sub-beams. The first grating 402 is used to transmit the M×P sub-beams to the lens 403. The lens 403 is used to transmit the M×P sub-beams to the first-level switching engine 103. The first-level switching engine 103 is used to receive the M×P sub-beams. The first-level switching engine 103 is a reflective switching engine. As shown in Figures d and e, the M×P sub-beams output by the first-level switching engine 103 are transmitted to the second area of ​​the first grating 402 after passing through the lens 403. The second area of ​​the first grating 402 and the first area of ​​the first grating 402 have different diffraction capabilities, thereby realizing the separation of the first light beam and the reflected light beam of the first-level switching engine 103. The second area of ​​the first grating 402 transmits the light beam to the lens 203. The lens 203 is a reflective lens. The lens 203 is used to reflect the light beam to the second area of ​​the first grating 402. As shown in FIG. f, the light beam output from the second area of ​​the first grating 402 is transmitted to the first-stage switching engine 103 again after passing through the lens 203. The first-stage switching engine 103 is used to reflect the light beam. The light beam output from the first-stage switching engine 103 passes through the lens 203, the first area of ​​the first grating 402, and the lens 201 in sequence.

[0057] It should be understood that Figure 6 and Figure 7 The optical path principle and Figure 4 The optical path principle of WSS is similar. Specifically, Figure 6 and Figure 7 The middle lens 401 is used to realize Figure 4 The functions of lens 401 and lens 406 are shown in FIG. Figure 6 and Figure 7 The first grating 402 is used to realize Figure 4 The functions of the first grating 402, the fourth grating 405, the second grating 202 and the third grating 204 are shown in FIG. Figure 6 and Figure 7 The first level switching engine 103 is used to implement Figure 4 The functions of the first level switching engine 103 and the second level switching engine 105. Figure 6 and Figure 7 The middle lens 403 is used to realize Figure 4 The functions of lens 403, lens 201, lens 205 and lens 404 are shown in FIG. Figure 6 and Figure 7 The middle lens 203 is used to realize Figure 4 The function of the lens 203. Figure 6 and Figure 7 For the description of WSS, please refer to the above Figure 4 Description in .

[0058] In the aforementioned Figure 3 , the distance between the second grating 202 and the third grating 204 is 3F. When the second grating 202 and the third grating 204 are the same grating, the light beam will pass through the second grating 202 twice. Therefore, the same grating can be represented as two different gratings on the optical path principle diagram. When the second grating 202 and the third grating 204 are the same grating, the distance between the second grating 202 and the third grating 204 is 3F, which refers to the distance between the second grating 202 and the third grating 204 on the optical path principle diagram. Similarly, when the other two optical elements are the same optical element, the distance between the two optical elements also represents the distance between the two optical elements on the optical path principle diagram.

[0059] according to Figure 6 and Figure 7 As can be seen from the description, by dividing the grating into two regions with different diffraction capabilities, the number of optical elements in the WSS can be reduced, thereby reducing the cost of the WSS. Figure 8 This is a schematic diagram of the structure of the first grating provided in the embodiment of the present application. Figure 8 As shown, the grating includes a grating plane 801 and a prism plane 802. The grating plane 801 includes a first region 8012 and a second region 8011. The first region 8012 and the second region 8011 have different diffraction capabilities. For example, the grating density of the first region 8012 is different from the grating density of the second region 8011. The grating density refers to the density of the lines on the grating. Figure 8 In the example of , the grating plane of the first region 8012 is the same as the grating plane of the second region 8011, that is, the grating plane of the first region 8012 and the grating plane of the second region 8011 are on the same plane. When the grating plane of the first region 8012 and the grating plane of the second region 8011 are different, that is, the grating plane of the first region 8012 and the grating plane of the second region 8011 are not on the same plane, the diffraction capabilities of the first region 8012 and the second region 8011 are also different. Figure 8 In the example, the prism surface of the first region 8012 is the same as the prism surface of the second region 8011. When the grating surface of the first region 8012 and the prism surface of the second region 8011 are different, that is, the grating surface of the first region 8012 and the prism surface of the second region 8011 are not on the same plane, the diffraction capabilities of the first region 8012 and the second region 8011 are also different.

[0060] According to the aforementioned Figure 2 It can be seen from the description that the embodiments of the present application can integrate the lens function on the grating. In practical applications, the lens function can be integrated on the grating by processing the grating surface into a curved surface. Alternatively, the lens function can be integrated by performing non-periodic scoring on the grating surface. The non-periodic scoring includes curved scoring and / or non-uniform scoring of the grating. Figure 6 and Figure 7 In the example of , the grating includes a first region and a second region. In this case, in order to reduce the cost of processing the grating, the lens function can be integrated through non-periodic lines.

[0061] The WSS provided in the present application is described above. The optical switching node provided in an embodiment of the present application is described below. In the present application, the optical switching node may be an optical switching node within a ROADM or a data center network. In other examples, the optical switching node may also be referred to as a wavelength crossconnect (WXC), an optical crossconnect (OXC), an optical switching node or a wavelength switching node, etc., and the embodiments of the present application do not impose specific restrictions on this. The optical switching node includes multiple WSSs. Multiple optical switching devices are indirectly or directly connected through optical fibers. Two examples of optical switching nodes provided in an embodiment of the present application are described below.

[0062] Fig. 9 The first structural diagram of the optical switching node provided in the embodiment of the present application. Fig. 9 As shown, the optical switching node 900 includes three wave splitters (i.e., wave splitter 904, wave splitter 905, and wave splitter 906), three WSSs (i.e., WSS 901, WSS 902, and WSS 903), and three combiners (i.e., combiner 907, combiner 908, and combiner 909). Each of the three wave splitters is used to receive an input light beam and split the input light beam into three sub-beams of different wavelengths. Each of the three WSSs is used to receive three sub-beams from the three wave splitters. The three wave splitters correspond to the three sub-beams one-to-one. For the description of the WSS, please refer to the aforementioned Figures 1 to 7 Description in any figure. The three sub-beams correspond to the three incident beams received by the aforementioned WSS. Each WSS is used to obtain three second beams according to the three sub-beams, and transmit a second beam to each of the three combiners. Each of the three combiners is used to receive three second beams from the three WSSs, combine the three second beams, and obtain an output beam. The three WSSs correspond one to one with the three second beams.

[0063] Fig.10 This is a second structural diagram of an optical switching node provided in an embodiment of the present application. Fig.10 As shown, the optical switching node 1000 includes three WSSs on the input side (ie, WSS1001, WSS1002, and WSS1003), three switching WSSs (ie, WSS1004, WSS1005, and WSS1006), and three WSSs on the output side (ie, WSS1007, WSS1008, and WSS1009). Fig.10In the example, the nine WSSs are all 3*3 (i.e., three input ports and three output ports) WSSs. The output port of each WSS on the input side is connected to the input port of each switching WSS. The output port of the switching WSS is connected to the input port of each WSS on the output side. The nine WSSs shown in this embodiment are located at different positions. This embodiment does not limit the number of WSSs included in the optical switching node and the position of each WSS. The switching WSS is used to exchange the transmission direction of the optical signal to achieve flexible scheduling of the optical signal. Taking WSS1001 as an example, WSS1001 can transmit the optical signal to any WSS on the output side by switching WSS.

[0064] It should be understood that Fig. 9 and Fig.10 This is just an example provided by the embodiment of the present application. In practical applications, those skilled in the art can adaptively modify the structure of the optical switching node according to requirements.

[0065] The embodiment of the present application also provides an optical communication system, Fig.11 This is a schematic diagram of the structure of the optical communication system provided in this application. Fig.11 As shown, the optical communication system 1600 includes a plurality of optical switching nodes. For the description of the optical switching nodes, please refer to the aforementioned Fig. 9 or Fig.10 Description of Fig.11 As shown, the optical communication system 1600 shown in this embodiment includes an optical switching node 1601, an optical switching node 1602, an optical switching node 1603, an optical switching node 1604, and an optical switching node 1605. It should be clear that the description of the number of optical switching nodes included in the optical communication system 1600 in this embodiment is an optional example and is not limited. The optical communication system 1600 also includes an optical fiber connected between two optical switching nodes. Taking the optical switching node 1601 and the optical switching node 1605 as an example, the optical communication system 1600 also includes an optical fiber 1606 connected between the optical switching node 1601 and the optical switching node 1605. This embodiment does not limit the connection relationship between the multiple optical switching nodes included in the optical communication system 1600.

[0066] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be covered by the protection scope of the present application.

Claims

1. A wavelength selective switch WSS, characterized in that: It includes M input ports, a first grating, a first-stage switching engine, a second grating, a lens group, a third grating, a second-stage switching engine, a fourth grating and N output ports, wherein: The M input ports are used to receive M first light beams and transmit the M first light beams to the first grating, the M first light beams correspond to the M input ports one by one, M is an integer greater than 1, the first grating is used to split each of the M first light beams into P sub-beams to obtain M×P sub-beams, P is an integer greater than 1, and the M×P sub-beams are transmitted to the first-level switching engine, and the first-level switching engine is used to apply a switching angle to the M×P sub-beams; the second grating, the lens group and the third grating are located between the first-level switching engine and the second-level switching engine, and at least one lens in the lens group is located Between the second grating and the third grating, in the height plane, the second grating, the lens group and the third grating are used to convert the emission angle characteristics of the output light beam of the first-stage switching engine into the incident position characteristics of the second-stage switching engine, in the dispersion plane, the second grating is used to combine the M×P sub-beams after the switching angle to obtain multiple target beams, the third grating is used to split the multiple target beams to obtain the M×P sub-beams after the switching angle, and the second grating, the lens group and the third grating are used to image the M×P sub-beams after the switching angle output by the first-stage switching engine to the second-stage switching engine; The second-level switching engine is used to receive the M×P sub-beams after the switching angle, adjust the output angles of the M×P sub-beams after the switching angle, and transmit the M×P sub-beams after the adjusted output angles to the fourth grating, and the fourth grating is used to combine the M×P sub-beams after the adjusted output angles to obtain N second beams, and the N output ports are used to output the N second beams, N is an integer greater than 1, and the N second beams and the N output ports correspond one to one.

2. The WSS according to claim 1, characterized in that: The first grating, the second grating and the third grating are the same grating, and the first grating includes a first area and a second area; The first grating is used to split each of the M first light beams into P sub-beams to obtain M×P sub-beams, including: the first area of ​​the first grating is used to split each of the M first light beams into P sub-beams to obtain the M×P sub-beams; in the height plane, the second grating, the lens group and the third grating are used to implement the port switching of the light beam, including: the lens group and the second area of ​​the first grating are used to implement the port switching of the light beam; In the dispersion plane, the second grating, the lens group and the third grating are used to image the M×P sub-beams after the switching angle output by the first-level switching engine to the second-level switching engine, including: the lens group and the second area of ​​the first grating are used to image the M×P sub-beams after the switching angle output by the first-level switching engine to the second-level switching engine.

3. The WSS according to claim 2, characterized in that: The grating density of the first region is different from the grating density of the second region.

4. The WSS according to claim 2 or 3, characterized in that: The grating plane of the first region is different from the grating plane of the second region, or, The prism surface of the first region is different from the prism surface of the second region.

5. The WSS according to any one of claims 2 to 4, characterized in that: The second region of the first grating has an integrated lens function.

6. The WSS according to claim 5, characterized in that: The second region realizes a lens function through non-periodic lines.

7. The WSS according to claim 5 or 6, characterized in that: The lens group includes a first lens, a second lens and a third lens, the second grating is located on the light transmission path of the first lens and the second lens, the third grating is located on the light transmission path between the second lens and the third lens, and the focal length of the second lens on the height plane is different from the focal length of the second lens on the dispersion plane.

8. The WSS according to claim 7, characterized in that: The lens group is a 2F optical path or an odd multiple of 2F optical path on the height plane, and the lens group is a 4F optical path or an integer multiple of 4F optical path on the dispersion plane.

9. The WSS according to claim 7 or 8, characterized in that: The second grating is a reflective grating, and the first lens and the third lens are the same lens.

10. The WSS according to any one of claims 5 to 9, characterized in that: The second region is integrated with a lens function on the dispersion plane, the focal length of the second region on the dispersion plane is F, the second region is not integrated with a lens function on the height plane, the distance between the second grating and the third grating is 2F, the focal length of the second lens on the height plane is F, and the focal length of the second lens on the dispersion plane is F / 2.

11. The WSS according to any one of claims 5 to 9, characterized in that: The second region is integrated with a lens function on the height plane, the focal length of the second region on the height plane is F, the second region is not integrated with a lens function on the dispersion plane, the distance between the second grating and the third grating is 3F, the second lens includes a first spherical lens, a first cylindrical lens and a second spherical lens, the focal lengths of the first spherical lens and the second spherical lens are F / 2, the focal length of the first cylindrical lens on the height plane is infinite, and the focal length of the first cylindrical lens on the dispersion plane is -F / 4.

12. The WSS according to claim 11, characterized in that: The first cylindrical lens is a reflective lens, and the first spherical lens and the second spherical lens are the same spherical lens.

13. A reconfigurable optical add / drop multiplexer (ROADM), characterized in that: Comprising one or more WSSs as claimed in any one of claims 1 to 12.

14. An optical switching system, characterized in that: The method comprises the ROADM of claim 13 and another ROADM, wherein the ROADM is configured to transmit a second optical beam to the another ROADM.

Images