Large-scale matrix optical switch and optical communication equipment based on 4f optical system

Abstract

The present application belongs to the field of optical fiber communication, and specifically discloses a large-scale matrix optical switch and optical communication equipment based on a 4f optical system. Through the present application, a first positive lens group is added between the optical front end and the first LCOS chip to form a 4f optical system, so that the Gaussian spot waist of the outgoing light beam of the optical front end is located at the optical front end, and a second positive lens group is added between the second LCOS chip and the optical back end to form a 4f optical system, so that the Gaussian spot waist of the incident light beam of the optical back end is located at the optical back end. The first positive lens group and the second positive lens group can map the spot arrays at the optical front end and the optical back end to the surfaces of the first LCOS chip and the second LCOS chip, respectively, so that the number of ports of the matrix optical switch can be increased.

Description

Technical Field

[0001] The present application belongs to the field of optical fiber communication, and more specifically, to a large-scale matrix optical switch and optical communication equipment based on a 4f optical system. Background Art

[0002] Large-scale (>100×100 ports) matrix optical switches have a wide range of application needs in data centers and computing centers. There are many technical solutions to realize large-scale matrix optical switches, and one of the technical solutions with practical prospects is the liquid crystal on silicon (LCOS) technology, which realizes beam deflection and optical path switching through two pure phase-modulated LCOS chips. The LCOS chip that controls beam deflection is a fully solid-state component. There is no mechanical moving part in the entire matrix optical switch, so it has the advantage of high reliability.

[0003] LCOS matrix optical switches usually consist of an optical front end, an LCOS chip, a concave reflector, an LCOS chip, and an optical back end, forming a W-shaped optical path in a plane; or by setting a two-dimensional prism group in front of the LCOS chip, the W-shaped optical path is folded into a three-dimensional optical path. In order to avoid mutual interference between the optical front end and the concave reflector, a certain distance needs to be set between the optical front end and the LCOS chip. According to the transmission characteristics of the Gaussian beam, the spot size at the optical front end will be larger than the spot size at the LCOS chip, and the port spacing is positively correlated with the spot size, thus restricting the scale of the matrix optical switch, that is, the number of input / output ports. Summary of the invention

[0004] In view of the defects of the prior art, the purpose of this application is to provide a large-scale matrix optical switch and optical communication equipment based on a 4f optical system, aiming to solve the problem that the number of input / output ports of the existing matrix optical switch is restricted by the port spacing.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides a large-scale matrix optical switch based on a 4f optical system, comprising an optical front end, a first positive lens group, a first LCOS chip, a concave reflector, a second LCOS chip, a second positive lens group and an optical back end arranged in sequence along an optical path;

[0006] The first LCOS chip and the second LCOS chip are both located on the focal plane of the concave reflector, and the three together constitute a 2f optical system;

[0007] The first positive lens group and the second positive lens group have the same structure, both consisting of a first positive lens and a second positive lens, the focal lengths of the two positive lenses in the positive lens group are the same or different, and the focal points coincide;

[0008] The optical front end is located on the front focal plane of the first positive lens in the first positive lens group, and the first LCOS chip is located on the back focal plane of the second positive lens in the first positive lens group, and the four together constitute a 4f optical system, so that the Gaussian spot waist of the outgoing light beam of the optical front end is located at the optical front end;

[0009] The optical back end is located on the front focal plane of the first positive lens in the second positive lens group, and the second LCOS chip is located on the back focal plane of the second positive lens in the second positive lens group, and the four together constitute a 4f optical system, so that the Gaussian spot waist of the incident light beam at the optical back end is located at the optical back end;

[0010] Under the premise that driving voltage is applied to both the first LCOS chip and the second LCOS chip, two groups of parallel light beams generated by polarization diversity from each port of the optical front end are diffracted by the first LCOS chip and reflected by the concave reflector, and are respectively incident on the center positions of the upper and lower halves of the second LCOS chip.

[0011] Preferably, the focal lengths of the two positive lenses in the positive lens group satisfy the following conditions:

[0012]

[0013] in, F 1 is the focal length of the first positive lens, F 2 is the focal length of the second positive lens, D is the side length of the pixel area allocated to a single port on the first LCOS chip, D 0 is the port spacing in the optical front end.

[0014] Preferably, the first positive lens group and the second positive lens group are arranged in parallel and combined into one positive lens group.

[0015] Preferably, the optical front end and the optical back end are arranged in parallel and merged into one optical front end.

[0016] Preferably, two LCOS chips are arranged in parallel and merged into one LCOS chip.

[0017] Preferably, the port spacing in the optical front end is 3.3-3.5 times the Gaussian spot radius of the port, and the port spacing in the optical back end is 3.3-3.5 times the Gaussian spot radius of the port.

[0018] Preferably, a first one-dimensional prism group is further provided in front of the first LCOS chip, and a second one-dimensional prism group is further provided in front of the second LCOS chip;

[0019] The first prism group and the second prism group have the same structure. The former applies additional deflection to two mutually parallel linear polarized light beams after polarization diversity at each port of the optical front end through refraction on the xz plane, and the latter applies additional deflection to the linear polarized light beams reflected by the concave reflector through refraction on the xz plane, so as to correct them to be mutually parallel.

[0020] Under the premise that no driving voltage is applied to the first LCOS chip and the second LCOS chip, two groups of parallel light beams generated by polarization diversity from each port of the optical front end are refracted by the first one-dimensional prism group, reflected by the first LCOS chip, reflected by the concave reflector and refracted by the second one-dimensional prism group, and then incident on the center positions of the upper and lower halves of the second LCOS chip respectively.

[0021] Preferably, a first two-dimensional prism group is further provided in front of the first LCOS chip, and a second two-dimensional prism group is further provided in front of the second LCOS chip;

[0022] The first two-dimensional prism group and the second two-dimensional prism group have the same structure, wherein the first two-dimensional prism group applies an additional deflection in the xz plane to two beams of mutually parallel linear polarized light after polarization diversity at each port of the optical front end through refraction on the xz plane, applies an additional deflection in the yz plane to two beams of mutually parallel linear polarized light after polarization diversity at each port of the optical front end through refraction on the yz plane, and the second two-dimensional prism group applies an additional deflection in the xz plane to the linear polarized light reflected by the concave reflector through refraction on the xz plane, so that the linear polarized light is corrected to be parallel to each other, and applies an additional deflection in the yz plane to the linear polarized light reflected by the concave reflector through refraction on the yz plane, so that the linear polarized light is parallel to the output light of the optical front end;

[0023] Under the premise that no driving voltage is applied to the first LCOS chip and the second LCOS chip, two groups of parallel light beams generated by polarization diversity from each port of the optical front end are successively refracted in two dimensions by the first two-dimensional prism group, reflected by the first LCOS chip, reflected by the concave reflector, and refracted in two dimensions by the second two-dimensional prism group, and then are incident on the center positions of the upper and lower halves of the second LCOS chip respectively.

[0024] To achieve the above-mentioned objectives, in a second aspect, the present application provides an optical communication device, including a large-scale matrix optical switch based on the 4f optical system and a circuit control board as described in the first aspect; the circuit control board is used to provide a phase control signal for the first LCOS chip and the second LCOS chip in the large-scale matrix optical switch.

[0025] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:

[0026] The present application provides a large-scale matrix optical switch and optical communication equipment based on a 4f optical system. A first positive lens group is added between an optical front end and a first LCOS chip to form a 4f optical system, so that the Gaussian spot waist of an outgoing light beam of the optical front end is located at the optical front end, and a second positive lens group is added between a second LCOS chip and an optical back end to form a 4f optical system, so that the Gaussian spot waist of an incident light beam of the optical back end is located at the optical back end. The first positive lens group and the second positive lens group can map the spot arrays at the optical front end and the optical back end to the surfaces of the first LCOS chip and the second LCOS chip, respectively, so that the number of ports of the matrix optical switch can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of a large-scale matrix optical switch structure based on a 4f optical system provided in Example 1 of the present application.

[0028] Figure 2 This is a schematic diagram of the optical front-end structure provided in Example 1 of the present application.

[0029] Figure 3 It is a Gaussian beam propagation diagram with or without a 4f optical system provided in Example 1 of the present application, wherein (a) corresponds to no 4f optical system, and (b) corresponds to a 4f optical system.

[0030] Figure 4 This is a schematic diagram of a large-scale matrix optical switch structure based on a 4f optical system provided in Example 2 of the present application.

[0031] Figure 5 This is a schematic diagram of a large-scale matrix optical switch structure based on a 4f optical system provided in Example 3 of the present application.

[0032] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0033] 1-optical front end, 2-first positive lens group, 3-first LCOS chip, 4-concave reflector, 5-second LCOS chip, 6-second positive lens group, 7-optical back end, 8-first one-dimensional prism group, 9-second one-dimensional prism group, 8'-first two-dimensional prism group, 9'-second two-dimensional prism group, 11-two-dimensional collimator array, 12-polarization beam splitter prism, 13-half-wave plate. DETAILED DESCRIPTION

[0034] For ease of understanding, the English abbreviations and related technical terms involved in the embodiments of the present application are explained and described below.

[0035] Positive lens, also known as converging lens or convex lens, is a lens that is thick in the middle and thin around the edges and has the ability to converge light.

[0036] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0037] Example 1

[0038] like Figure 1 As shown, the present application provides a large-scale matrix optical switch based on a 4f optical system, comprising an optical front end 1, a first positive lens group 2, a first LCOS chip 3, a concave reflector 4, a second LCOS chip 5, a second positive lens group 6 and an optical back end 7 arranged in sequence along the optical path. The first LCOS chip 3 and the second LCOS chip 5 are both located on the focal plane of the concave reflector, and the three together constitute a 2f optical system.

[0039] The first positive lens group 2 and the second positive lens group 6 have the same structure, and are both composed of a first positive lens and a second positive lens. The focal lengths of the two positive lenses in the positive lens group are the same or different, and the focal points coincide.

[0040] The optical front end 1 is located on the front focal plane of the first positive lens in the first positive lens group 2, and the first LCOS chip 3 is located on the back focal plane of the second positive lens in the first positive lens group 2. The four together constitute a 4f optical system, so that the Gaussian spot waist of the outgoing light beam of the optical front end is located at the optical front end.

[0041] The optical back end 7 is located on the front focal plane of the first positive lens in the second positive lens group 6, and the second LCOS chip 5 is located on the back focal plane of the second positive lens in the second positive lens group 6. The four together constitute a 4f optical system, so that the Gaussian spot waist of the incident light beam at the optical back end is located at the optical back end.

[0042] Under the premise that driving voltage is applied to both the first LCOS chip 3 and the second LCOS chip 5, two groups of parallel light beams generated by polarization diversity from each port of the optical front end are diffracted by the first LCOS chip and reflected by the concave reflector, and are respectively incident on the center positions of the upper and lower halves of the second LCOS chip.

[0043] The optical front end 1 transforms the small spot divergent beam at the output end of the optical fiber into a collimated beam with a large spot, and performs polarization diversity to obtain two parallel linear polarized beams with the same polarization state. The optical back end has the same structure as the optical front end, except that the beams are transmitted in the reverse direction; each port in the optical back end 7 combines two parallel linear polarized beams with the same polarization state into one beam, and then couples it to the output optical fiber through the optical fiber collimator.

[0044] like Figure 2 As shown, the optical front end 1 includes a two-dimensional collimator array 11, a polarization beam splitter prism 12 and a half-wave plate 13. The two-dimensional collimator array 11 has M×Nports, each of which transforms the small spot divergent light beam at the output end of the optical fiber into a collimated light beam with a large spot. The polarization beam splitter prism 12 is a glued prism composed of a triangular prism and an rhombus prism. A polarization beam splitter film is coated on the glued surface of the two prisms. It can transmit p-waves (polarized light with the light vector parallel to the paper surface) and reflect s-waves (polarized light with the light vector perpendicular to the paper surface). After a beam of randomly polarized light passes through the polarization beam splitter prism 12, two parallel linear polarized light beams with orthogonal polarization states are obtained. After one of the light beams passes through the half-wave plate 13, the polarization state of the two light beams is rotated 90°. Finally, the two light beams are parallel to each other and have the same polarization state, realizing polarization diversity. Therefore, in the optical front end 1, a group of ( M×N After polarization diversity, two groups (each M×N ) parallel beams with the same polarization state.

[0045] The pure phase-modulated LCOS chip is a pixelated element that can control the refractive index of the liquid crystal layer in each pixel through the electrically controlled birefringence effect, thereby controlling the phase delay of the reflected light beam of each pixel. The LCOS chip can form a dynamic phase grating by controlling the phase of each pixel, control the (reflective) diffraction direction of the light beam, and can be adjusted dynamically. The LCOS chip consists of multiple blocks, each of which corresponds to a port of the optical front end of the matrix optical switch, and controls the diffraction direction of a beam of polarized light separated by polarization diversity, and guides it to the target output port.

[0046] The first LCOS chip 3 and the second LCOS chip 5 are both arranged on the focal plane of the concave reflector 4, forming a 2f optical system, and the light spots on the first LCOS chip 3 and the second LCOS chip 5 are of the same size. The first LCOS chip 3 and the second LCOS chip 5 are each divided into two upper and lower half areas, respectively processing a beam of polarized light separated by polarization diversity.

[0047] The first positive lens group 2 is composed of two lenses with confocal settings, which are arranged between the optical front end 1 and the first LCOS chip 3, and maps the light spot array at the optical front end 1 to the surface of the first LCOS chip 3, and the two light spots have the same size; the second positive lens group 6 is composed of two lenses with confocal settings, which are arranged between the optical back end 7 and the second LCOS chip 5, and maps the light spot array at the optical back end 7 to the surface of the second LCOS chip 5, and the two light spots have the same size.

[0048] The Gaussian beams at the optical front end 1 and the optical back end 7 are transmitted to the surface of the LCOS chip. Since the waist of the Gaussian beam is located on the surface of the LCOS chip, the spot size on the surface of the LCOS chip is smaller than that at the optical front end 1 and the optical back end 7, which will reduce the number of ports of the matrix optical switch. The two positive lenses of the first positive lens group 2 are arranged confocally, the optical front end 1 is located at the front focal plane of the first positive lens of the first positive lens group 2, the first LCOS chip 3 is located at the back focal plane of the second positive lens of the first positive lens group 2, and the optical front end 1, the first positive lens group 2 and the first LCOS chip 3 form a 4f optical system. The two positive lenses of the second positive lens group 6 are arranged confocally, the optical back end 7 is located at the front focal plane of the first positive lens of the second positive lens group 6, the second LCOS chip 5 is located at the back focal plane of the second positive lens of the second positive lens group 6, and the second LCOS chip 5, the second positive lens group 6 and the optical back end 7 form a 4f optical system. The first positive lens group 2 and the second positive lens group 6 can map the spot arrays at the optical front end and the optical back end to the surfaces of the first LCOS chip 3 and the second LCOS chip 5, respectively, so that the number of ports of the matrix optical switch can be increased.

[0049] When there is no positive lens group between the optical front end 1 and the first LCOS chip 3, the Gaussian beam transmission process of the incident light path is as follows: Figure 3 As shown in (a), the waist of the Gaussian beam is located on the surface of the first LCOS chip 3, and the corresponding waist radius of the Gaussian beam is ω 0, the distance between the first LCOS chip 3 and the optical front end 1 is Z , then the spot size at the optical front end 1 is ω As shown in formula (1). In order to minimize the light spot emitted by the optical front end 1, formula (2) needs to be satisfied. At this time, the light spot size of the optical front end is as shown in formula (3).

[0050] (1)

[0051] (2)

[0052] (3)

[0053] On the surface of the first LCOS chip 3, a size of D × D Rectangular block, in Figure 3 In the architecture shown in (a), the port spacing in the optical front end 1 should also be D × D In order to ensure that the port aperture can cover the Gaussian spot and retain a certain boundary isolation between the ports, it is generally required to satisfy equation (4).

[0054] (4)

[0055] In fact, on the surface of the first LCOS chip 3, as long as the size is D 0=3.3 ω The block of 0 is enough to cover the Gaussian spot, so the utilization rate of the pixel area on the first LCOS chip 3 is only 50% as shown in formula (5). η Limited by the ratio of the Gaussian spot radius to the beam waist radius of the optical front end 1. D is the block size divided on the LCOS chip, D 0 is the port spacing in the optical front end.

[0056] (5)

[0057] like Figure 3 As shown in (b), a first positive lens group 2 is set between the optical front end 1 and the first LCOS chip 3. The focal points of the two positive lenses in the first positive lens group 2 coincide, and the optical front end 1 and the first LCOS chip 3 are respectively located on the focal planes of the two positive lenses, then the optical front end 1, the first positive lens group 2, and the first LCOS chip 3 constitute a 4f system. The spot radius at the optical front end 1 ω The spot radius on the surface of the first LCOS chip 3 ω 0 satisfies formula (6), where F 1 and F 2 are the focal lengths of the two lenses in the lens group.

[0058] (6)

[0059] At the same time, due to the change of the Gaussian beam with respect to the lens, when the waist of the Gaussian beam of the outgoing light of the first positive lens group 2 is located on the first LCOS chip 3, the waist of the Gaussian beam of the incident light of the first positive lens group 2 is located on the optical front end 1. The first positive lens group 2 realizes the movement of the waist position of the Gaussian beam. At this time, the Gaussian spot radius of the optical front end 1 is equal to its waist radius, and the Gaussian spot radius of the first LCOS chip 3 is equal to its waist radius. Therefore, it can be ensured at the same time D 0=3.3 ω 0 and D =3.3 ω , which can make full use of the pixel area on the LCOS chip.

[0060] For example, setting the wavelength λ =1550nm, the distance between the first LCOS chip 3 and the optical front end 1 is Z=30mm, and the spot radius on the LCOS chip is obtained according to equations (2) and (3): ω 0=121.7μm, spot radius at the optical front end ω=172.05μm. Using a 4K pixel LCOS chip with a pixel size of 3.6μm, the size of the entire active area is 14.75mm×8.06mm. It is divided into two half-areas to process two beams of polarization diversity respectively, and the size of each half-area is 7.38mm×8.06mm. Figure 3 In the structure shown in (a), the area allocated to each spot is 3.3 ω ×3.3 ω= 567.8μm×567.8μm, the maximum number of ports allowed is 12×13=156; if Figure 3 In the structure shown in (b), the area allocated to each spot is 3.3 ω 0×3.3 ω 0 = 401.6 μm×401.6 μm, the maximum number of ports allowed is 18×20=360. It can be seen that after adding the first positive lens group 2 and the second positive lens group 6, the number of ports of the matrix optical switch increases by 130%.

[0061] According to the imaging law of the lens, the focal lengths of the two positive lenses in the first positive lens group 2 are D , D 0 satisfies formula (7).

[0062] (7)

[0063] in, F 1 is the focal length of the first positive lens, F 2 is the focal length of the second positive lens, D is the block size divided on the LCOS chip, D 0 is the port spacing in the optical front end.

[0064] When determining the port spacing in the optical front end D 0 and the block size divided on the LCOS chip D , the focal length ratio of the two positive lenses in the first positive lens group 2 is determined.

[0065] The first LCOS chip 3 requires at least a 50×50 pixel area to achieve the deflection of the light beam. Therefore, for a 2K LCOS with a pixel pitch of 8 μm, D>400 μm. For a 4K LCOS with a pixel pitch of 3.6 μm, D>180 μm.

[0066] Preferably, the first positive lens group and the second positive lens group are arranged in parallel and combined into one positive lens group.

[0067] Specifically, the first positive lens of the first positive lens group 2 and the first positive lens of the second positive lens group 6 can be combined into one positive lens, and the second positive lens of the first positive lens group 2 and the second positive lens of the second positive lens group 6 can be combined into one positive lens to simplify the structure of the matrix optical switch.

[0068] Preferably, the optical front end and the optical back end are arranged in parallel and combined into one optical front end to simplify the structure of the matrix optical switch.

[0069] Preferably, two LCOS chips are arranged in parallel and merged into one LCOS chip, so as to further simplify the device structure of the matrix optical switch.

[0070] Preferably, the port spacing in the optical front end and the optical back end is 3.3-3.5 times the port Gaussian spot radius, so as to increase the number of ports of the matrix optical switch with the smallest possible port spacing. The block division on the LCOS chip should also be the same as the port spacing in the optical front end 1 and the optical back end 7.

[0071] Example 2

[0072] Preferably, if Figure 4 As shown, a first one-dimensional prism group 8 is provided in front of the first LCOS chip, and a second one-dimensional prism group 9 is provided in front of the second LCOS chip.

[0073] The first one-dimensional prism group 8 and the second one-dimensional prism group 9 have the same structure and have a wedge angle in the x direction, which can deflect the light beam in the xz plane. The first one-dimensional prism group 8 applies additional deflection to the two beams of linear polarization after polarization diversity at each port of the optical front end through refraction to reduce the deflection angle requirement of the first LCOS chip. The second one-dimensional prism group 9 applies additional deflection to the linear polarization reflected by the concave reflector through refraction on the xz plane, which can offset the additional deflection applied by the former, and correct the reflected light beams of the upper and lower halves of the second LCOS chip to be parallel to each other, so as to reduce the deflection angle requirement of the second LCOS chip.

[0074] Under the premise that no driving voltage is applied to the first LCOS chip and the second LCOS chip, two groups of parallel light beams generated by polarization diversity from each port of the optical front end are refracted by the first one-dimensional prism group, reflected by the first LCOS chip, reflected by the concave reflector and refracted by the second one-dimensional prism group, and then incident on the center positions of the upper and lower halves of the second LCOS chip respectively.

[0075] The specific structure of the one-dimensional prism group includes but is not limited to the following situations:

[0076] 1) It is formed by gluing two identical quadrangular prisms together. When viewed from the side, the quadrangular prism is a right-angled trapezoid. The right-angled thick ends of the two quadrangular prisms are aligned, and the first prism group formed is a roof shape;

[0077] 2) It is composed of two identical prisms. When viewed from the side, the prisms are right triangles. The thin ends of the two prisms are aligned, and the first prism group is V-shaped.

[0078] After a one-dimensional prism group is set in front of the LCOS chip, the diffraction angle θ of the LCOS chip xmax The requirement is reduced by half (from MD / f Reduced to MD / 2 f, f is the focal length of the concave reflector, M × N is the number of ports of the optical front end, D × D is the pixel area size allocated to a single port on the first LCOS chip), thereby increasing the diffraction efficiency and reducing the loss of the matrix optical switch. In other words, when the diffraction angle of the LCOS chip is constant, this optical design can realize a matrix optical switch with more ports.

[0079] Example 3

[0080] Preferably, if Figure 5 As shown, a first two-dimensional prism group 8 ′ is further provided in front of the first LCOS chip 3 , and a second two-dimensional prism group 9 ′ is further provided in front of the second LCOS chip 5 .

[0081] The first two-dimensional prism group 8' and the second two-dimensional prism group 9' have the same structure, and both have a wedge angle in the x direction and a wedge angle in the y direction. The wedge angle in the x direction of the first two-dimensional prism group is used to apply an additional deflection in two dimensions to the two beams of linear polarization after polarization diversity at each port of the optical front end through refraction, so as to reduce the deflection angle requirement of the first LCOS chip. The wedge angle in the x direction of the second two-dimensional prism group is used to offset the additional deflection applied by the former and correct the reflected light beams of the upper and lower halves of the second LCOS chip to be parallel to each other, so as to reduce the deflection angle requirement of the second LCOS chip. The wedge angles in the y direction of the first two-dimensional prism group and the second two-dimensional prism group are used to fold the entire optical route of the matrix optical switch from a planar structure into a three-dimensional structure.

[0082] Under the premise that no driving voltage is applied to the first LCOS chip and the second LCOS chip, two groups of parallel light beams generated by polarization diversity from each port of the optical front end are successively refracted in two dimensions by the first two-dimensional prism group, reflected by the first LCOS chip, reflected by the concave reflector, and refracted in two dimensions by the second two-dimensional prism group, and then are incident on the center positions of the upper and lower halves of the second LCOS chip respectively.

[0083] Conventional one-dimensional prisms have a wedge angle in only one direction, which can produce one-dimensional deflection of the light beam; two-dimensional prisms have wedge angles in both the x-direction and the y-direction, which can produce two-dimensional deflection of the light beam. After the prism group is set before the two LCOS chips, the incident and output light beams are perpendicular to the LCOS chips.

[0084] The function of the first two-dimensional prism group 8' in the xz plane is: in the static state where no driving voltage is applied to the first LCOS chip 3, the light beams from all input ports can pass through the first two-dimensional prism group 8', the first LCOS chip 3 and the concave reflector 4 in sequence, and the two beams of polarization diversity are respectively incident on the center positions of the upper and lower halves of the second LCOS chip 5. The function of the first two-dimensional prism group 8' in the yz plane is: folding the entire optical path of the matrix optical switch from a planar structure into a three-dimensional optical path, making the structure of the optical switch more compact; reducing the incident angle of the light beam on the LCOS chip, increasing the diffraction efficiency, thereby reducing the loss of the matrix optical switch.

[0085] The second two-dimensional prism group 9' is arranged in front of the second LCOS chip 5, and its function in the xz plane is to correct the reflected light beams of the upper and lower halves of the second LCOS chip 5 to be parallel to each other, so as to facilitate reception by the optical back end; and its function in the yz plane is to cooperate with the first two-dimensional prism group 8' to realize the folding of the optical path from a planar structure into a three-dimensional optical path.

[0086] The specific structural design of the two-dimensional prism group includes but is not limited to the following situations:

[0087] 1) An integrated structure, with a side view of a roof prism and a top view of a wedge prism; or, with a side view of two identical prisms with their thin ends aligned, and a top view of a wedge prism;

[0088] 2) Composed of two one-dimensional prisms, one of which has a side view angle of a roof prism and a top view angle of flat glass, and the other has a side view angle of flat glass and a top view angle of a wedge prism; or, one of which has a side view angle of two identical triangular prisms with their thin ends aligned and a top view angle of flat glass, and the other has a side view angle of flat glass and a top view angle of a wedge prism;

[0089] 3) One-piece structure, the top view is a wedge-shaped prism, and the side view is two prisms with different wedge angles with thick ends aligned with thin ends;

[0090] 4) It is composed of two one-dimensional prisms, one of which has a roof prism when viewed from the side and a flat glass when viewed from the top, and the other has a wedge prism when viewed from the side and a wedge prism when viewed from the top; or, one of which has a side viewing angle of two identical triangular prisms with their thin ends aligned and a flat glass when viewed from the top, and the other has a wedge prism when viewed from the side and a wedge prism when viewed from the top.

[0091] Based on the above, the present application also provides an optical communication device, including a large-scale matrix optical switch based on the 4f optical system and a circuit control board as mentioned above; the circuit control board is used to provide a phase control signal for the first LCOS chip and the second LCOS chip in the large-scale matrix optical switch.

[0092] It should be understood that expressions such as "including" and "may include" that may be used in the present application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In the present application, terms such as "including" and / or "having" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0093] In addition, in the present application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0094] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the relative position relationship after connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0095] In addition, in the embodiments of the present application, the mathematical concepts mentioned are symmetry, equality, parallelism, verticality, etc. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense, and allow a small amount of deviation, approximation to symmetry, approximation to equality, approximation to parallelism, approximation to verticality, etc. are all possible. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0096] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A large-scale matrix optical switch based on a 4f optical system, characterized in that: It includes an optical front end, a first positive lens group, a first LCOS chip, a concave reflector, a second LCOS chip, a second positive lens group and an optical back end which are sequentially arranged along the optical path; The first LCOS chip and the second LCOS chip are both located on the focal plane of the concave reflector, and the three together constitute a 2f optical system; The first positive lens group and the second positive lens group have the same structure, both consisting of a first positive lens and a second positive lens, the focal lengths of the two positive lenses in the positive lens group are the same or different, and the focal points coincide; The optical front end is located on the front focal plane of the first positive lens in the first positive lens group, and the first LCOS chip is located on the back focal plane of the second positive lens in the first positive lens group, and the four together constitute a 4f optical system, so that the Gaussian spot waist of the outgoing light beam of the optical front end is located at the optical front end; The optical back end is located on the front focal plane of the first positive lens in the second positive lens group, and the second LCOS chip is located on the back focal plane of the second positive lens in the second positive lens group, and the four together constitute a 4f optical system, so that the Gaussian spot waist of the incident light beam at the optical back end is located at the optical back end; Under the premise that driving voltage is applied to both the first LCOS chip and the second LCOS chip, two groups of parallel light beams generated by polarization diversity from each port of the optical front end are diffracted by the first LCOS chip and reflected by the concave reflector, and are respectively incident on the center positions of the upper and lower halves of the second LCOS chip.

2. The large-scale matrix optical switch according to claim 1, characterized in that: The focal lengths of the two positive lenses in the positive lens group satisfy the following conditions: in, F 1 is the focal length of the first positive lens, F 2 is the focal length of the second positive lens, D is the side length of the pixel area allocated to a single port on the first LCOS chip, D 0 is the port spacing in the optical front end.

3. The large-scale matrix optical switch according to claim 1, characterized in that: The first positive lens group and the second positive lens group are arranged in parallel and combined into one positive lens group.

4. The large-scale matrix optical switch according to claim 1, characterized in that: The optical front end and the optical back end are arranged in parallel and merged into one optical front end.

5. The large-scale matrix optical switch according to claim 1, characterized in that: Two LCOS chips are arranged in parallel and merged into one LCOS chip.

6. The large-scale matrix optical switch according to any one of claims 1 to 5, characterized in that: The port spacing in the optical front end is 3.3-3.5 times the port Gaussian spot radius, and the port spacing in the optical back end is 3.3-3.5 times the port Gaussian spot radius.

7. The large-scale matrix optical switch according to any one of claims 1 to 5, characterized in that: A first one-dimensional prism group is also provided in front of the first LCOS chip, and a second one-dimensional prism group is also provided in front of the second LCOS chip; The first one-dimensional prism group and the second one-dimensional prism group have the same structure. The former applies additional deflection to two mutually parallel linear polarized light beams after polarization diversity at each port of the optical front end through refraction on the xz plane, and the latter applies additional deflection to the linear polarized light reflected by the concave reflector through refraction on the xz plane, so as to correct them to be mutually parallel. Under the premise that no driving voltage is applied to the first LCOS chip and the second LCOS chip, two groups of parallel light beams generated by polarization diversity from each port of the optical front end are refracted by the first one-dimensional prism group, reflected by the first LCOS chip, reflected by the concave reflector and refracted by the second one-dimensional prism group, and then incident on the center positions of the upper and lower halves of the second LCOS chip respectively.

8. The large-scale matrix optical switch according to any one of claims 1 to 5, characterized in that: A first two-dimensional prism group is also provided in front of the first LCOS chip, and a second two-dimensional prism group is also provided in front of the second LCOS chip; The first two-dimensional prism group and the second two-dimensional prism group have the same structure, wherein the first two-dimensional prism group applies an additional deflection in the xz plane to two beams of mutually parallel linear polarized light after polarization diversity at each port of the optical front end through refraction on the xz plane, applies an additional deflection in the yz plane to two beams of mutually parallel linear polarized light after polarization diversity at each port of the optical front end through refraction on the yz plane, and the second two-dimensional prism group applies an additional deflection in the xz plane to the linear polarized light reflected by the concave reflector through refraction on the xz plane, so that the linear polarized light is corrected to be parallel to each other, and applies an additional deflection in the yz plane to the linear polarized light reflected by the concave reflector through refraction on the yz plane, so that the linear polarized light is parallel to the output light of the optical front end; Under the premise that no driving voltage is applied to the first LCOS chip and the second LCOS chip, two groups of parallel light beams generated by polarization diversity from each port of the optical front end are successively refracted in two dimensions by the first two-dimensional prism group, reflected by the first LCOS chip, reflected by the concave reflector and refracted in two dimensions by the second two-dimensional prism group, and then incident on the center positions of the upper and lower halves of the second LCOS chip respectively.

9. An optical communication device, characterized in that: A large-scale matrix optical switch and a circuit control board as claimed in any one of claims 1 to 8; The circuit control board is used to provide a phase control signal for the first LCOS chip and the second LCOS chip in the large-scale matrix optical switch.

Images