Wavelength selective switch

Abstract

The application provides a wavelength selective switch, comprising: a light splitting module configured to split a first light into a plurality of second lights; a light diffraction module configured to receive and diffract the plurality of second lights to emit a plurality of third lights, the light diffraction module comprising a plurality of diffraction regions, each diffraction region configured to diffract a corresponding one of the plurality of second lights and emit a corresponding one of the plurality of third lights; and a light transmission module located in a light path of the plurality of third lights, the light transmission module comprising a plurality of output channels, each output channel configured to receive and output at least one target diffraction order of the plurality of third lights, a mode field radius of each output channel being equal to a beam waist radius of the at least one target diffraction order of the plurality of third lights; the beam waist radius of the at least one target diffraction order of the plurality of third lights being different from a beam waist radius of at least one of other diffraction orders of the at least one of the plurality of third lights, or / and the beam waist radius of the at least one target diffraction order of the plurality of third lights being different from a beam waist radius of at least one of the other of the plurality of third lights.

Description

Technical Field

[0001] This application relates to the field of optical communication, and more particularly to a wavelength selective switch. Background Technology

[0002] Wavelength selective switches (WSS) are widely used in optical communication, particularly in wavelength division multiplexing (OXC) cross-connects. A WSS receives an input light source containing multiple wavelengths and guides these wavelengths to different output ports. Each output port outputs one or more specific wavelengths of light, which serve as the signal light for that port, while other wavelengths constitute the crosstalk. The difference between the insertion loss (IL) of the signal light and the crosstalk is defined as the isolation. Isolation is a crucial indicator of WSS performance, and improving it is a pressing technical challenge. Summary of the Invention

[0003] This application provides a wavelength selective switch, including:

[0004] A beam splitting module is used to receive a first beam and split the first beam to output multiple second beams, the multiple second beams having different wavelengths;

[0005] An optical diffraction module, located in the optical path of the multiple second beams, is used to receive and diffract the multiple second beams to emit multiple third beams. The optical diffraction module includes multiple diffraction regions, each corresponding one-to-one with the multiple second beams. Each diffraction region is used to diffract one corresponding second beam and emit one third beam.

[0006] An optical transmission module is located on the optical path of the multiple third beams. The optical transmission module includes multiple output channels. Each output channel is used to receive and output at least one target diffraction level of the third beam. The mode field radius of each output channel is equal to the beam waist radius of the target diffraction level of the received at least one third beam.

[0007] The waist radius of the target diffraction order of the at least one third beam is different from the waist radius of at least one of the other diffraction orders of the at least one third beam, or / and the waist radius of the target diffraction order of the at least one third beam is different from the waist radius of at least one of the other third beams.

[0008] In the aforementioned wavelength selective switch, each output channel receives at least one target diffraction order of a third beam. For each output channel, by setting its mode field radius to be equal to the beam waist radius of the target diffraction order of the received third beam, the insertion loss of the signal light in the output channel can be reduced. By setting its mode field radius to be unequal to the beam waist radius of at least one diffraction order among the other diffraction orders in the received third beam (excluding the target diffraction order), or / and by setting its mode field radius to be unequal to the beam waist radius of at least one other third beam, the insertion loss of crosstalk light in the output channel can be increased. By reducing the insertion loss of the signal light in the output channel and increasing the insertion loss of the crosstalk light in the output channel, the isolation of the wavelength selective switch can be improved.

[0009] In some embodiments, the waist radius of the target diffraction order of the at least one third beam is different from the waist radius of any one of the other diffraction orders of the at least one third beam, or / and the waist radius of the target diffraction order of the at least one third beam is different from the waist radius of any one of the other third beams.

[0010] This increases the insertion loss of each crosstalk beam, which helps to further improve isolation.

[0011] In some embodiments, the wavelength selection switch further includes a plurality of lenses located between the optical diffraction module and the optical transmission module, the plurality of lenses corresponding one-to-one with the plurality of output channels; each of the lenses is used to receive the target diffraction order of the at least one beam of third light and focus it onto the corresponding output channel.

[0012] In some embodiments, the radii of curvature of the plurality of lenses are equal.

[0013] In this way, each lens is used to focus the third light to the corresponding output channel, so that the third light can be better coupled to the output channel and the light energy loss of the third light can be reduced.

[0014] In some embodiments, the radius of curvature of at least one lens is different from the radius of curvature of the other lenses.

[0015] Thus, when the curvature radii of the lenses are different, the beam waist radius of the third light focused by the lenses can be different. By setting the curvature radius of each lens, the beam waist radius of the target diffraction order of the third light guided by each lens is equal to the mode field radius of the corresponding output channel. Furthermore, by setting the curvature radius of at least one lens to be different from that of the other lenses, the beam waist radius of the target diffraction order of the third light guided by the at least one lens is different from that of the other third lights. This means that the beam waist radius of the other third lights is different from the mode field radius of the output channel corresponding to the at least one lens. The above can achieve mode field matching between the third light guided by the at least one lens and the corresponding output channel, and achieve mode field mismatch between the other third lights and the corresponding output channel. Therefore, it can reduce the insertion loss of the signal light and increase the insertion loss of the crosstalk light, thereby improving the isolation.

[0016] In some embodiments, the radii of curvature of the plurality of lenses are not equal.

[0017] This results in the beam waist radius of the third light focused by each lens being unequal, so the mode field radius of each output channel is different from the beam waist radius of any crosstalk light, which can further increase the insertion loss of each crosstalk light, thereby helping to further improve the isolation.

[0018] In some embodiments, the optical diffraction module is a silicon-based liquid crystal, and the beam waist radius of each diffraction order of the multiple beams of third light is adjusted by adjusting the driving voltage applied to the multiple diffraction regions respectively.

[0019] Thus, when the driving voltage applied to the driving electrode changes, the beam waist radius of the third light emitted by the optical diffraction module changes. During the operation of the wavelength selective switch, the value of the corresponding driving voltage can be queried according to the required beam waist radius and applied to each driving electrode, so that the mode field radius of each output channel is equal to the beam waist radius of the target diffraction level of the received at least one beam of third light. This makes the beam waist radius of the target diffraction level of the at least one beam of third light different from the beam waist radius of at least one of the other diffraction levels of the at least one beam of third light, or / and the beam waist radius of the target diffraction level of the at least one beam of third light different from the beam waist radius of at least one of the other third lights, thereby reducing the insertion loss of the signal light and increasing the insertion loss of the crosstalk light, and improving the isolation of the wavelength selective switch.

[0020] In some embodiments, the target diffraction order includes a diffraction order.

[0021] In some embodiments, the target diffraction order is +1 diffraction order.

[0022] Thus, since the light intensity of the +1 diffraction order is the highest, and the target diffraction order is the +1 diffraction order, a large light utilization rate can be guaranteed.

[0023] In some embodiments, the target diffraction order includes two diffraction orders.

[0024] With the improved isolation of the wavelength selective switch, crosstalk between the output channels is reduced, and the wavelength selective switch can be configured to achieve "bilateral diffraction", thereby improving the integration of the wavelength selective switch.

[0025] In some embodiments, the target diffraction order includes a +1 diffraction order and a -1 diffraction order.

[0026] Thus, since the light intensity of the +1 and -1 diffraction orders is the highest, the target diffraction order includes both the +1 and -1 diffraction orders, which can ensure a large light utilization rate.

[0027] In some embodiments, the optical transmission module further includes an input channel for receiving the first light and transmitting the first light to the beam splitter.

[0028] In this way, both the first optical input wavelength selection switch and the third optical output wavelength selection switch are implemented through the optical transmission module, which helps to reduce the overall size of the wavelength selection switch and simplify the optical path structure of the wavelength selection switch.

[0029] In some embodiments, the beam waist radius of each wavelength in the first light is equal.

[0030] Thus, the first light includes light of multiple wavelengths. Since light of multiple wavelengths is transmitted in the input channel, in order to reduce the insertion loss of light of various wavelengths in the first light, the beam waist radius of light of various wavelengths in the first light is equal, and the beam waist radius of light of various wavelengths in the first light is equal to the mode field radius of the input channel, thereby improving the utilization rate of light of various wavelengths in the first light. Attached Figure Description

[0031] Figure 1 This is a module structure diagram of the wavelength selection switch according to Embodiment 1 of this application.

[0032] Figure 2 This is a schematic diagram of the wavelength selection switch according to Embodiment 1 of this application.

[0033] Figure 3 This is a schematic diagram of the process of the third optical coupling to the optical transmission module in the wavelength selection switch of Embodiment 1 of this application.

[0034] Figure 4 This is a graph showing the change in isolation of the wavelength selective switch in Embodiment 1 of this application.

[0035] Figure 5 This is a schematic diagram of the process of the third optical coupling to the optical transmission module in the wavelength selection switch of Embodiment 2 of this application.

[0036] Figure 6 This is a schematic diagram of the process of the third optical coupling to the optical transmission module in the wavelength selection switch of Embodiment 3 of this application.

[0037] Explanation of main component symbols

[0038] Wavelength Selective Switch 100

[0039] 10 Spectrometer Module

[0040] Optical diffraction module 20

[0041] Diffraction region 21

[0042] Drive electrode 22

[0043] Optical transmission module 30

[0044] Output channels 31, 311

[0045] Input channel 32

[0046] Lens 40

[0047] First Light L1

[0048] Second Light L2

[0049] Third Light L3

[0050] Wavelengths λ1, λ2, λ3...λn

[0051] Direction X, Y Detailed Implementation

[0052] The embodiments of this application are described below with reference to the accompanying drawings.

[0053] Example 1

[0054] Wavelength selective switches are used in optical communication systems to guide received mixed-wavelength light to different output channels according to different wavelengths.

[0055] Please see Figure 1 The wavelength selection switch 100 in this embodiment includes a beam splitting module 10, an optical diffraction module 20, and an optical transmission module 30. The beam splitting module 10 receives a first light L1 and splits it into multiple second light beams L2 for emission. The optical diffraction module 20 receives the multiple second light beams L2 and diffracts them to output multiple third light beams L3. The optical transmission module 30 receives the multiple third light beams L3 and outputs them from multiple output channels.

[0056] In this embodiment, the first light L1, the second light L2, and the third light L3 are all Gaussian beams. The first light L1 includes light of various wavelengths. The first light L1 is output from a light source (e.g., a laser) or optical device (e.g., an optical fiber) external to the wavelength selective switch 100. Please refer to [link to relevant documentation]. Figure 2 In this embodiment, the beam splitting module 10 is a diffraction grating. The beam splitting module 10 receives the first light L1 and diffracts it to emit multiple beams of second light L2. Each beam of second light L2 has a different wavelength. Figure 2 Using azimuth as a reference, the horizontal direction is defined as the X direction, and the vertical direction as the Y direction. Multiple beams of second light L2 emitted from the beam splitter 10 are arranged sequentially along the X direction. In this embodiment, the beam splitter 10 is used to emit N beams of second light L2. Figure 2 Based on the reference, the wavelengths of the second light L2 arranged from left to right along the X direction are denoted as λ1, λ2, λ3...λn.

[0057] In this embodiment, the optical diffraction module 20 is a silicon-based liquid crystal. The optical diffraction module 20 is located in the optical path of multiple second beams L2, and is used to receive and diffract the multiple second beams L2. Due to the birefringence effect of the liquid crystal, by applying a specific voltage to the optical diffraction module 20, the multiple second beams L2 are diffracted by the optical diffraction module 20. The diffracted light exiting the optical diffraction module 20 is defined as the third beam L3. When second beams L2 of different wavelengths are incident on the optical diffraction module 20, they are diffracted in different directions by the optical diffraction module 20, thereby guiding each beam of third beam L3 to different output ports in the optical transmission module 30, achieving the purpose of wavelength-based beam splitting (i.e., obtaining a specific wavelength of third beam L3 output from a specific output channel). In other embodiments, the optical diffraction module 20 can also be a micro-electro-mechanical system (MEMS), etc.

[0058] The optical diffraction module 20 includes multiple diffraction regions 21. In this embodiment, each diffraction region 21 is rectangular, and the multiple diffraction regions 21 are arranged in parallel with each other. Each of the multiple diffraction regions 21 corresponds one-to-one with multiple beams of second light L2. Each diffraction region 21 is used to receive and diffract its corresponding beam of second light L2 to correspondingly emit a third light L3. That is, the optical diffraction module 20 includes N diffraction regions 21, to... Figure 2 Based on this, N diffraction regions 21 are numbered 1, 2, 3...N from left to right. Diffraction region 21 numbered 1 is used to receive and diffract the second light L2 with wavelength λ1, diffraction region 21 numbered 2 is used to receive and diffract the second light L2 with wavelength λ2, diffraction region 21 numbered 3 is used to receive and diffract the second light L2 with wavelength λ3, and diffraction region 21 numbered N is used to receive and diffract the second light L2 with wavelength λn.

[0059] The optical diffraction module 20 includes multiple electrically insulated driving electrodes 22. These driving electrodes 22 are arranged in an array comprising multiple rows (X-direction) and multiple columns (Y-direction), with an equal number of driving electrodes 22 in each row and an equal number in each column. In this embodiment, multiple columns of driving electrodes 22 are arranged within each diffraction region 21. Each driving electrode 22 receives a driving voltage independently. By controlling the driving voltage on the multiple columns of driving electrodes 22 within each diffraction region 21, the angle of the third light L3 emitted from each diffraction region 21 can be controlled, i.e., the emission direction of the third light L3 from each diffraction region 21 can be controlled, thereby guiding multiple beams of third light L3 through the multiple diffraction regions 21 to the corresponding output channels in the optical transmission module 30.

[0060] Please see Figure 3 In this embodiment, the optical transmission module 30 includes multiple output channels 31, each of which is an optical fiber. The multiple output channels 31 are arranged along the Y-direction. That is, in this embodiment, the arrangement of the multiple output channels 31 is perpendicular to the arrangement direction of the multiple diffraction regions 21. Each output channel 31 is used to receive at least one third beam L3. That is, the multiple output channels 31 are not one-to-one with the multiple beams of third beam L3. For one output channel 31, it may be used to receive one or more beams of third beam L3. The number of third beams L3 received by each output channel 31 and the wavelength of the third beam L3 received by each output channel 31 are determined according to the optical path after the output channel 31 outputs the third beam L3. This application does not limit the number and wavelength of the third beam L3 received by each output channel 31.

[0061] Each third beam L3 has multiple diffraction orders: -M……-3,-2,-1,0,+1,+2,+3……+M. Figure 3 The horizontal axis represents each diffraction order at each diffraction angle, and the vertical axis represents the light intensity I of each diffraction order. Each output channel 31 is used to receive one of the diffraction orders of the third light L3. The diffraction order received by the output channel 31 is defined as the target diffraction order. Since the light intensity of the +1 diffraction order is the largest, in order to ensure a large light utilization rate, in this embodiment, multiple output channels 31 are used to receive and output multiple beams of the third light L3 at the +1 diffraction order. That is, in this embodiment, the target diffraction order of the multiple output channels 31 is the +1 diffraction order. In other embodiments, the target diffraction order can also be the +2 diffraction order, etc., and the light intensity of the +2 diffraction order can be adjusted to reach the light intensity of the +1 diffraction order, or slightly less than the light intensity of the +1 diffraction order, by setting the diffraction angle, etc., to ensure a large light utilization rate. This application does not impose any special limitations on the selection of the target diffraction order.

[0062] Taking output channel 311 as an example, if output channel 311 is used to receive the +1 diffraction order of the third light L3 with wavelength λ1, then for output channel 311, the +1 diffraction order of the third light L3 with wavelength λ1 is the signal light of output channel 311, while the other diffraction orders of the third light L3 with wavelength λ1 and the third light L3 with other wavelengths are all crosstalk light of output channel 311. The distinction between signal light and crosstalk light in other output channels 31 is similar and will not be elaborated further.

[0063] To improve the performance of the wavelength selective switch 100, for each output channel 31, as much signal light as possible should be received and crosstalk light should be avoided as much as possible. Both signal light and crosstalk light experience insertion loss (IL) when incident on the output channel 31. A higher insertion loss indicates greater energy loss during incident light. Therefore, lower insertion loss for the signal light and higher insertion loss for the crosstalk light are more beneficial for improving the performance of the wavelength selective switch 100. The difference between the insertion losses of the signal light and the crosstalk light is defined as the isolation. Higher isolation results in better performance of the wavelength selective switch 100.

[0064] Therefore, in this embodiment, isolation is improved in the following two aspects:

[0065] Firstly, isolation is improved by reducing the insertion loss of the signal light.

[0066] To reduce the insertion loss of the signal light, the mode field radius of each output channel 31 is set to be equal to the beam waist radius of the target diffraction level of the third light L3 it receives. This ensures that the mode field of each output channel 31 is matched with the target diffraction level of the third light L3 it receives, which helps reduce the insertion loss of the signal light. Taking output channel 311 as an example, output channel 311 is used to receive the +1 diffraction level of the third light L3 with wavelength λ1. Setting the mode field radius of output channel 311 to be equal to the beam waist radius of the +1 diffraction level of the third light L3 with wavelength λ1 ensures that the mode field of output channel 311 is matched with the +1 diffraction level of the third light L3 with wavelength λ1, thereby reducing the insertion loss when the +1 diffraction level of the third light L3 with wavelength λ1 couples to output channel 311.

[0067] Secondly, isolation can be improved by increasing the insertion loss of crosstalk light.

[0068] To increase the insertion loss of crosstalk light, the mode field radius of each output channel 31 is set to be different from the waist radius of at least one crosstalk light (crosstalk light with different wavelengths is considered to be different types of crosstalk light, and light with different diffraction orders is also considered to be different types of crosstalk light).

[0069] Taking output channel 311 as an example, setting the mode field radius of output channel 311 to be different from the beam waist radius of at least one crosstalk light can cause the mode field of output channel 311 to be mismatched with that of at least one crosstalk light, thereby increasing the insertion loss of at least one crosstalk light incident on output channel 311, which makes it difficult for crosstalk light to be incident on output channel 311.

[0070] In a modified embodiment of this application, the mode field radius of each output channel 31 is set to be different from the beam waist radius of the third light L3 received by its adjacent output channels 31, and / or the mode field radius of each output channel 31 is set to be different from the beam waist radius of the diffraction orders in the third light L3 received by it, excluding the target diffraction order. For each output channel 31, it is easier to receive crosstalk light that is closer in distance and less likely to receive crosstalk light that is farther in distance. Therefore, increasing the insertion loss of the crosstalk light that is closer in distance is more conducive to efficiently improving the isolation. For each output channel 31, the crosstalk light that is closer in distance is the third light L3 received by the adjacent output channels 31 and the diffraction orders in the third light L3 received by the channel itself, excluding the target diffraction order. Therefore, in this modified embodiment, by setting the mode field radius of each output channel 31 to be different from the beam waist radius of the third light L3 received by the adjacent output channel 31, or / and setting the mode field radius of each output channel 31 to be different from the beam waist radius of the diffraction order in the third light L3 received by it, excluding the target diffraction order, it is beneficial to efficiently improve the isolation.

[0071] In another modified embodiment of this application, the mode field radius of each output channel 31 is different from the waist radius of any crosstalk light, which can increase the insertion loss of each crosstalk light, thereby helping to further improve the isolation.

[0072] Therefore, in this embodiment, the wavelength selective switch 100, by reducing the insertion loss of the signal light and increasing the insertion loss of the crosstalk light for each output channel 31, can improve the isolation and effectively enhance the performance of the wavelength selective switch 100.

[0073] For each output channel 31, its mode field radius depends on the material and structure of the optical fiber. Therefore, once the output channel is manufactured, its mode field radius is immutable. In this embodiment, the beam waist radius of the signal light and the beam waist radius of the crosstalk light are adjusted by adjusting the voltage applied to each driving electrode 22, so that the mode field of the signal light matches that of the output channel 31, and the mode field of the crosstalk light is mismatched with that of the output channel 31.

[0074] When the driving voltage applied to each driving electrode 22 changes, the beam waist radius of the third light L3 emitted from the optical diffraction module 20 will change. The correspondence between the driving voltage value and the beam waist radius value can be stored as a lookup table through prior experimentation or pre-calculation according to an algorithm. Thus, during the operation of the wavelength selection switch 100, the corresponding driving voltage value can be looked up according to the required beam waist radius value and applied to each driving electrode 22.

[0075] Let η represent the isolation degree, and ω1 and ω2 represent the beam waist radius of the third beam L3 and the mode field radius of the output channel 31, respectively. The following formula is satisfied: By setting a fixed value for either ω1 or ω2, we can obtain a curve showing how the isolation degree η changes as the other value changes. For example, Figure 4 The figure shows the curve of the isolation η as the value of the other ω1 or ω2 changes when one of them is 40 micrometers. Figure 4 The horizontal axis represents the value of the aforementioned "other one," and the vertical axis represents the isolation degree η. From Figure 4 It can be seen that when one of ω1 and ω2 is set to 40 micrometers and the other is also set to 40 micrometers, the isolation η is the minimum. When the value of the other ω2 deviates from 40 micrometers, the isolation η increases. The greater the deviation of the other ω2 from 40 micrometers, the greater the increase in the isolation η. Therefore, it can be concluded that by setting the beam waist radius of the third beam L3 to be equal to the mode field radius of the output channel 31, the isolation can be improved.

[0076] Please refer to the following: Figure 3 In this embodiment, the optical transmission module 30 further includes an input channel 32. The input channel 32 is also an optical fiber. The input channel 32 is used to receive the first light L1 and transmit the first light L1 to the beam splitter 10. That is, in this embodiment, the input of the first light L1 to the wavelength selection switch 100 and the output of the third light L3 from the wavelength selection switch 100 are both achieved through the optical transmission module 30, which helps to reduce the overall size of the wavelength selection switch 100 and simplify the optical path structure of the wavelength selection switch 100.

[0077] In this embodiment, the first light L1 includes light of various wavelengths. Since light of various wavelengths is transmitted in the input channel 32, in order to reduce the insertion loss of light of various wavelengths in the first light L1, the beam waist radius of light of various wavelengths in the first light L1 is equal, and the beam waist radius of light of various wavelengths in the first light L1 is equal to the mode field radius of the input channel 32, thereby improving the utilization rate of light of various wavelengths in the first light L1.

[0078] For the optical transmission module 30, both the input channel 32 and the output channel 31 are optical transmission channels and are structurally similar. Depending on the direction of light output, in other embodiments, the input channel 32 can also serve as the output channel 31, and vice versa. Whether an optical transmission channel is specifically an input channel or an output channel depends on the direction in which the optical transmission channel transmits light.

[0079] In this embodiment, the wavelength selection switch 100 further includes multiple lenses 40. Each lens 40 corresponds one-to-one with a multiple output channel 31. Each lens 40 is located between an output channel 31 and the optical diffraction module 20. In this embodiment, all lenses 40 have the same radius of curvature. Each lens 40 is used to focus the third light L3 to the corresponding output channel 31, thereby improving the coupling of the third light L3 to the output channel 31 and reducing the light energy loss of the third light L3.

[0080] In this embodiment, the wavelength selection switch 100 may also include other necessary components, such as a polarizer for converting the first light L1 into linearly polarized light, and light guiding elements (e.g., reflectors, cylindrical lenses) for guiding the transmission of the first light L1, the second light L2, and the third light L3. This application mainly describes components relevant to this application. Other components will not be described in detail. Furthermore, the number of component structures shown in the accompanying drawings of this embodiment is not intended to limit this application; for example… Figure 2 The number of driving electrodes 22 in each diffraction region 21 shown, or Figure 3 The number of output channels 31 and input channels 32 shown are as described. The number of the above components may vary in different embodiments; the accompanying drawings are for illustrative purposes only.

[0081] In this embodiment, the wavelength selective switch 100 has an output channel 31 for receiving at least one target diffraction level of a third beam L3. For each output channel 31, by setting its mode field radius to be equal to the waist radius of the target diffraction level of the received third beam L3, the insertion loss of the signal light in the output channel 31 can be reduced. By setting its mode field radius to be unequal to the waist radius of at least one diffraction level among the other diffraction levels of the received third beam L3 (excluding the target diffraction level), or / and by setting its mode field radius to be unequal to the waist radius of at least one third beam L3, the insertion loss of the crosstalk light in the output channel 31 can be increased. By reducing the insertion loss of the signal light in the output channel 31 and increasing the insertion loss of the crosstalk light in the output channel 31, the isolation of the wavelength selective switch 100 can be improved.

[0082] Example 2

[0083] Please see Figure 5The wavelength selection switch in this embodiment differs from the wavelength selection switch 100 in Embodiment 1 mainly in the method of adjusting the beam waist radius of the third light L3. In this embodiment, the beam waist radius of the third light L3 is adjusted by adjusting the curvature radius of each lens 40, instead of adjusting the beam waist radius of the third light L3 by adjusting the driving voltage on the driving electrode 22 in Embodiment 1. The effect of the light diffraction module 20 on the second light L2 can be equivalent to that of a lens; therefore, in the aforementioned Embodiment 1, adjusting the driving voltage on each driving electrode 22 can also be considered equivalent to adjusting the curvature radius of a lens.

[0084] When the radii of curvature of the lenses 40 are different, the waist radius of the third light L3 focused by the lenses 40 can be different. In this embodiment, by setting the radii of curvature of each lens 40, the waist radius of the target diffraction order of the third light guided by each lens 40 is equal to the mode field radius of the corresponding output channel 31. Furthermore, by setting the radii of curvature of at least one lens 40 to be different from the radii of curvature of the other lenses 40, the waist radius of the target diffraction order of the third light L3 guided by the at least one lens 40 is different from the waist radius of the other third light L3, which means that the waist radius of the other third light L3 is different from the mode field radius of the output channel 31 corresponding to the at least one lens 40. The above can achieve mode field matching between the third light L3 guided by the at least one lens 40 and the corresponding output channel 31, and achieve mode field mismatch between the other third light L3 and the corresponding output channel 31, thereby reducing the insertion loss of the signal light and increasing the insertion loss of the crosstalk light, and improving the isolation.

[0085] In a modified embodiment of this example, the radii of curvature of the multiple lenses 40 are not equal, so that the waist radius of the third light L3 focused by each lens 40 is not equal. As a result, the mode field radius of each output channel 31 is different from the waist radius of any crosstalk light, which can further increase the insertion loss of each crosstalk light, thereby helping to further improve the isolation.

[0086] The wavelength selective switch of this embodiment can achieve all the beneficial effects of the wavelength selective switch 100 in Embodiment 1. Furthermore, this embodiment also provides a technical solution that replaces the adjustment of the driving voltage on the multiple driving electrodes 22 by adjusting the curvature radius of the multiple lenses 40.

[0087] In one modified embodiment of this application, the beam waist radius of the signal light and the beam waist radius of the crosstalk light of each output channel 31 can be adjusted simultaneously with the adjustment of the driving voltage applied to each driving electrode 22, thereby adjusting the beam waist radius of each third light L3. This makes the signal light match the mode field of the output channel 31 and makes the crosstalk light mismatch the mode field of the output channel 31, thereby improving the isolation from these two aspects.

[0088] In another modified embodiment of this application, in addition to improving the isolation by utilizing the principles of mode field matching and mode field mismatch, the isolation of the wavelength selective switch is further improved by utilizing the principles of coherent cancellation and radial mismatch.

[0089] As mentioned above, in this embodiment, each output channel 31 is used to receive one or more beams of the +1 diffraction order of the third light L3. By adjusting the driving voltage on each driving electrode 22, the phase of the other diffraction orders of the third light L3 can be adjusted, so that the other diffraction orders in each third light L3, except for the +1 diffraction order, at least partially cancel each other out, reducing the amount of diffraction orders in the third light L3, except for the +1 diffraction order, coupled to the output channel 31. That is, crosstalk light is reduced by coherent cancellation, increasing the insertion loss of crosstalk light, which is beneficial to improving isolation. As for radial mismatch, it can be achieved by increasing the spacing between each output channel 31.

[0090] Therefore, the other modified embodiment described above, in addition to achieving the aforementioned beneficial effects, also helps to further improve the isolation of the wavelength selective switch.

[0091] Example 3

[0092] The wavelength selection switch in this embodiment differs from the wavelength selection switch in Embodiment 1 mainly in the arrangement of the output channel 31 and the input channel 32.

[0093] Please see Figure 6 In this embodiment, the optical transmission module 30 includes multiple output channels 31 and an input channel 32.

[0094] In Embodiment 1, the input channel 32 and multiple output channels 31 are arranged in parallel, with the input channel located on the same side of the multiple output channels 31. That is, in Embodiment 1, the optical transmission module 30 includes multiple parallel optical transmission channels, wherein the leftmost or rightmost optical transmission channel serves as the optical input channel 32.

[0095] In this embodiment, the input channel 32 and multiple output channels 31 are arranged in parallel, with the multiple output channels 31 located on both sides of the input channel 32. That is, with... Figure 6 Based on the orientation, in this embodiment, some output channels 31 are located to the left of the input channel 32, and other output channels 31 are located to the right of the input channel 32. Furthermore, in this embodiment, the number of output channels 31 located to the left and right of the input channel 32 is equal. In a modified embodiment of this embodiment, the number of output channels 31 located to the left and right of the input channel 32 may be different.

[0096] The wavelength selective switch in this embodiment achieves all the beneficial effects of the wavelength selective switch 100 in this embodiment, thus effectively improving the isolation of the wavelength selective switch. Based on the improved isolation of the wavelength selective switch, crosstalk between the various output channels 31 is reduced, allowing the wavelength selective switch in this embodiment to achieve "bilateral diffraction." That is, in this embodiment, multiple output channels 31 are located on both sides of the input channel 32, and the third light L3 is output from the output channels 31 on both sides of the input channel 32. Furthermore, in this embodiment, the target diffraction order includes two diffraction orders: a +1 diffraction order and a -1 diffraction order, which are output from the output channels 31 on the left and right sides of the input channel 32, respectively.

[0097] The wavelength selective switch in this embodiment employs the aforementioned "bilateral diffraction," which effectively reduces the spacing between multiple output channels 31 and input channels 32, thereby improving the integration of the wavelength selective switch.

[0098] In this embodiment, the arrangement of the input channel 32 and the multiple output channels 31 can also be applied to Embodiment 2, and the same technical effect can be achieved.

[0099] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A wavelength selective switch, characterized in that, include: A beam splitting module is used to receive a first beam and split the first beam to output multiple second beams, the multiple second beams having different wavelengths; An optical diffraction module, located in the optical path of the multiple second beams, is used to receive and diffract the multiple second beams to emit multiple third beams. The optical diffraction module is a silicon-based liquid crystal and includes multiple diffraction regions. Each of the multiple diffraction regions corresponds one-to-one with the multiple second beams. Each diffraction region is used to diffract a corresponding second beam and emit a third beam. By adjusting the driving voltage applied to the multiple diffraction regions, the beam waist radius of each diffraction order of the multiple third beams is adjusted respectively. as well as An optical transmission module is located on the optical path of the multiple third beams. The optical transmission module includes an input channel and multiple output channels located on both sides of the input channel. The input channel is used to receive the first light and transmit the first light to the beam splitter. Each output channel is used to receive and output at least one target diffraction level of the third beam. The mode field radius of each output channel is equal to the beam waist radius of the target diffraction level of the received at least one third beam. Each third beam is output from two output channels located on both sides of the input channel. The waist radius of the target diffraction order of the at least one third beam is different from the waist radius of at least one of the other diffraction orders of the at least one third beam, and the waist radius of the target diffraction order of the at least one third beam is different from the waist radius of at least one of the other third beams.

2. The wavelength selective switch as described in claim 1, characterized in that, The waist radius of the target diffraction order of the at least one third beam is different from the waist radius of any one of the other diffraction orders of the at least one third beam, or / and the waist radius of the target diffraction order of the at least one third beam is different from the waist radius of any one of the other third beams.

3. The wavelength selective switch as described in claim 1, characterized in that, It also includes a plurality of lenses located between the optical diffraction module and the optical transmission module, and the plurality of lenses correspond one-to-one with the plurality of output channels; Each of the lenses is used to receive the target diffraction order of the at least one beam of third light and focus it onto the corresponding output channel.

4. The wavelength selective switch as described in claim 3, characterized in that, The radii of curvature of the plurality of lenses are equal.

5. The wavelength selective switch as described in claim 3, characterized in that, At least one lens has a radius of curvature different from that of the other lenses.

6. The wavelength selective switch as described in claim 5, characterized in that, The radii of curvature of the multiple lenses are not equal.

7. The wavelength selective switch as described in any one of claims 1-6, characterized in that, The target diffraction order includes one diffraction order.

8. The wavelength selective switch as described in claim 7, characterized in that, The target diffraction order is +1.

9. The wavelength selective switch as described in any one of claims 1-6, characterized in that, The target diffraction order includes two diffraction orders.

10. The wavelength selective switch as described in claim 9, characterized in that, The target diffraction order includes a +1 diffraction order and a -1 diffraction order.

11. The wavelength selective switch according to any one of claims 1-10, characterized in that, The beam waist radius of each wavelength in the first light is equal.

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