CN115561862A

CN115561862A - Wavelength selective switch

Info

Publication number: CN115561862A
Application number: CN202110751349.9A
Authority: CN
Inventors: 郭正伟; 柳贺良; 李兆明; 丁必锋
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-07-02
Filing date: 2021-07-02
Publication date: 2023-01-03
Also published as: WO2023274317A1

Abstract

The present application provides a wavelength selective switch comprising: the light splitting module is used for splitting the first light to output a plurality of second lights; the light diffraction module is used for receiving and diffracting the second light beams to emit a third light beam and comprises a plurality of diffraction zones, and each diffraction zone is used for diffracting the corresponding second light beam and emitting a third light beam; the optical transmission module is positioned on the optical path of the multiple beams of third light and comprises a plurality of output channels, each output channel is used for receiving and outputting at least one target diffraction order of the third light, and the mode field radius of each output channel is equal to the beam waist radius of the received at least one target diffraction order of the third light; the beam waist radius of the target diffraction order of the at least one third light is different from the beam waist radius of at least one of the other diffraction orders of the at least one third light, or/and the beam waist radius of the target diffraction order of the at least one third light is different from the beam waist radius of at least one of the other third lights.

Description

Wavelength selective switch

Technical Field

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

Background

Wavelength Selective Switch (WSS) devices are widely used in the field of Optical communications, in particular in the field of Optical cross-connect (OXC). The WSS is used for receiving an input light, the input light comprises light with a plurality of wavelengths, and the WSS is also used for guiding the light with the plurality of wavelengths to different output ports according to different wavelengths. For each output port, it is used to output one or more specific wavelengths of light, where the one or more specific wavelengths of light are signal light of the output port, and the other wavelengths of light are crosstalk light of the output port. The difference between Insertion Loss (IL) of signal light and crosstalk light is defined as isolation. Isolation is an important index of the WSS, and how to improve isolation is a technical problem to be solved urgently.

Disclosure of Invention

The present application provides a wavelength selective switch comprising:

a light splitting module for receiving and splitting a first light to output a plurality of second lights having different wavelengths;

a light diffraction module, disposed on an optical path of the plurality of second lights, for receiving and diffracting the plurality of second lights to emit a plurality of third lights, the light diffraction module including a plurality of diffraction regions, wherein the plurality of diffraction regions are in one-to-one correspondence with the plurality of second lights, and each diffraction region is configured to diffract a corresponding one of the plurality of second lights and emit a corresponding one of the third lights; and

the optical transmission module is positioned on an optical path of the plurality of third lights and comprises a plurality of output channels, each output channel is used for receiving and outputting the target diffraction order of at least one third light, and the mode field radius of each output channel is equal to the beam waist radius of the received target diffraction order of the at least one third light;

the beam waist radius of the target diffraction order of the at least one third light is different from the beam waist radius of at least one of the other diffraction orders of the at least one third light, or/and the beam waist radius of the target diffraction order of the at least one third light is different from the beam waist radius of at least one of the other third lights.

In the wavelength selective switch, each output channel is configured to receive a target diffraction order of at least one third light beam, and for each output channel, the insertion loss of the signal light of the output channel can be reduced by setting the mode field radius of the output channel to be equal to the beam waist radius of the target diffraction order of the at least one third light beam received by the output channel; the mode field radius is set to be unequal to the beam waist radius of at least one of the other diffraction orders except the target diffraction order in the received third light, or/and the mode field radius is set to be unequal to the beam waist radius of at least one of the other third light, so that the insertion loss of the crosstalk light of the output channel can be increased. The isolation of the wavelength selective switch can be improved by reducing the insertion loss of the signal light of the output channel and increasing the insertion loss of the crosstalk light of the output channel.

In some embodiments, a beam waist radius of the target diffraction order of the at least one third light is different from a beam waist radius of any one of other diffraction orders of the at least one third light, or/and a beam waist radius of the target diffraction order of the at least one third light is different from a beam waist radius of any one of other third lights.

In this way, the insertion loss of each crosstalk light can be increased, thereby contributing to further improvement of the isolation.

In some embodiments, the wavelength selective switch further comprises a plurality of lenses between the optical diffraction module and the optical transmission module, the plurality of lenses corresponding to the plurality of output channels one to one; each lens is used for receiving the target diffraction order of the at least one beam of third light and focusing the target diffraction order to the corresponding output channel.

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

In this way, each lens is used for focusing the third light to the corresponding output channel, so that the third light is better coupled to the output channel, and the optical energy loss of the third light is reduced.

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

Thus, when the curvature radii of the lenses are different, the beam waist radii of the third light focused by the lenses can be different, and by setting the curvature radius of each lens, the beam waist radii of the target diffraction orders of the third light guided by each lens are equal to the mode field radii of the corresponding output channels; moreover, by setting the curvature radius of at least one lens to be different from the curvature radii of 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 the beam waist radii of other third lights, that is, the beam waist radii of the other third lights are different from the mode field radii of the output channels corresponding to the at least one lens, so that the third light guided by the at least one lens can be matched with the mode field of the corresponding output channel, and the other third lights can be mismatched with the mode field of the corresponding output channel, thereby reducing the insertion loss of the signal light, increasing the insertion loss of the crosstalk light, and improving the isolation.

In some embodiments, the radii of curvature of the plurality of lenses are different from each other.

Therefore, the beam waist radii of the third light focused by the lenses are not equal, so that the mode field radius of each output channel is different from the beam waist radius of any crosstalk light, the insertion loss of each crosstalk light can be further increased, and the isolation is further improved.

In some embodiments, the light diffraction module is a liquid crystal on silicon, and the beam waist radii of the diffraction orders of the third light beams are respectively adjusted by respectively adjusting the driving voltages applied to the plurality of diffraction regions.

In this way, when the driving voltage applied to the driving electrode is changed, the beam waist radius of the third light emitted by the optical diffraction module changes, and in the working process of the wavelength selective switch, the value of the corresponding driving voltage can be queried according to the value of 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 order of the at least one beam of third light received, the beam waist radius of the target diffraction order of the at least one beam of third light is different from the beam waist radius of at least one of the other diffraction orders of the at least one beam of third light, or/and the beam waist radius of the target diffraction order of the at least one beam of third light is different from the beam waist radius of at least one of the other diffraction orders of the at least one beam of third light, thereby achieving the purposes of 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.

In some embodiments, the target diffraction order comprises one diffraction order.

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

Therefore, the light intensity of the +1 diffraction order is the maximum, and the target diffraction order is the +1 diffraction order, so that the high light utilization rate can be ensured.

In some embodiments, the target diffraction order comprises two diffraction orders.

On the basis of improving the isolation of the wavelength selective switch, the crosstalk among all output channels is reduced, and the wavelength selective switch can be arranged to realize bilateral diffraction, so that the integration level of the wavelength selective switch is improved.

In some embodiments, the target diffraction orders include a +1 diffraction order and a-1 diffraction order.

Thus, as the light intensity of the +1 diffraction order and the-1 diffraction order is the maximum, the target diffraction order comprises the +1 diffraction order and the-1 diffraction order, and larger light utilization rate can be ensured.

In some embodiments, the optical transmission module further includes an input channel for receiving the first light and transmitting the first light to the optical splitting module.

Therefore, the first light input wavelength selective switch and the third light output from the wavelength selective switch are realized through the light transmission module, so that the whole size of the wavelength selective switch is favorably reduced, and the light path structure of the wavelength selective switch is simplified.

In some embodiments, the beam waist radii of each of the wavelengths of the first light are equal.

In this way, the first light includes light of multiple wavelengths, and since the light of multiple wavelengths is transmitted in the input channel, in order to reduce the insertion loss of the light of each wavelength in the first light, the beam waist radii of the light of each wavelength in the first light are equal, and the beam waist radii of the light of each wavelength in the first light are equal to the mode field radius of the input channel, thereby improving the utilization rate of the light of each wavelength in the first light.

Drawings

Fig. 1 is a block diagram of a wavelength selective switch according to a first embodiment of the present application.

Fig. 2 is a schematic structural diagram of a wavelength selective switch according to a first embodiment of the present application.

Fig. 3 is a schematic process diagram of a wavelength selective switch according to a first embodiment of the present application, in which a third light is coupled to an optical transmission module.

Fig. 4 is a graph illustrating a variation in isolation of a wavelength selective switch according to an embodiment of the present invention.

Fig. 5 is a schematic process diagram of a third optical coupling to an optical transmission module in a wavelength selective switch according to a second embodiment of the present application.

Fig. 6 is a schematic process diagram of a third optical coupling to an optical transmission module in a wavelength selective switch according to a third embodiment of the present application.

Description of the main elements

Wavelength selective switch 100

Spectral module 10

Light diffraction module 20

Diffraction zone 21

Drive electrode 22

Optical transmission module 30

Output channel

31, 311

Input channel 32

Lens 40

First light L1

Second light L2

Third light L3

Wavelength lambda 1, lambda 2, lambda 3 \8230, 8230, lambda n

Directions X, Y

Detailed Description

The embodiments of the present application will be described below with reference to the drawings.

Example one

Wavelength selective switches are used in optical communication systems to direct received light of a mixed wavelength to different output channels depending on the wavelength.

Referring to fig. 1, a wavelength selective switch 100 of the present embodiment includes a light splitting module 10, a light diffraction module 20, and a light transmission module 30. The light splitting module 10 is configured to receive the first light L1 and split the first light L1 into a plurality of second lights L2 to exit. The light diffraction module 20 is configured to receive the plurality of second lights L2 and diffract the plurality of second lights L2 to output a plurality of third lights L3. The light transmission module 30 is configured to receive the plurality of third lights L3 and output the plurality of third lights L3 from a plurality of output channels.

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 a plurality of wavelengths. The first light L1 is output by a light source (e.g., a laser) or an optical device (e.g., an optical fiber) outside the wavelength selective switch 100. Referring to fig. 2, in the present embodiment, the light splitting module 10 is a diffraction grating. The light splitting module 10 is configured to receive the first light L1 and diffract the first light L1 to emit a plurality of second lights L2. Each of the second lights L2 has a different wavelength. With the orientation of fig. 2 as a reference, the horizontal direction is defined as the X direction and the vertical direction is defined as the Y direction. The plurality of second lights L2 emitted from the light splitting module 10 are sequentially arranged along the X direction. In this embodiment, the light splitting module 10 is configured to emit N beams of second light L2. The wavelengths of the second light L2 sequentially arranged from left to right in the X direction are represented by λ 1, λ 2, λ 3 \8230;. λ n, in this order with reference to fig. 2.

In this embodiment, the light diffraction module 20 is a liquid crystal on silicon (lcos). The light diffraction module 20 is located on the optical path of the second light L2, and is used for receiving the second light L2 and diffracting the second light L2. Due to the birefringence effect of the liquid crystal, a specific voltage is applied to the light diffraction module 20, so that the plurality of second lights L2 is diffracted by the light diffraction module 20. The diffracted light emitted from the light diffraction module 20 is defined as third light L3. After the second light L2 with different wavelengths enters the light diffraction module 20, the second light L2 is diffracted by the light diffraction module 20 in different directions, so that each beam of the third light L3 is guided to a different output port in the light transmission module 30, so as to achieve the purpose of splitting light according to the wavelengths (i.e. enabling the third light L3 with specific wavelengths to be output from a specific output channel). In other embodiments, the optical diffraction module 20 can also be a Micro-Electro-Mechanical System (MEMS) or the like.

The light diffraction module 20 includes a plurality of diffraction regions 21. In this embodiment, each diffraction region 21 is rectangular, and the plurality of diffraction regions 21 are arranged in parallel. The plurality of diffraction regions 21 correspond to the plurality of second lights L2 one to one, and each diffraction region 21 is configured to receive and diffract the corresponding one of the second lights L2 to emit a third light L3 correspondingly. That is, the light diffraction module 20 includes N diffraction regions 21, and the N diffraction regions 21 are numbered 1, 2, 3, 8230; N from left to right in sequence, based on fig. 2. The diffraction region 21 numbered 1 is configured to receive and diffract the second light L2 having the wavelength λ 1, the diffraction region 21 numbered 2 is configured to receive and diffract the second light L2 having the wavelength λ 2, the diffraction region 21 numbered 3 is configured to receive and diffract the second light L2 having the wavelength λ 3, and the diffraction region 21 numbered N is configured to receive and diffract the second light L2 having the wavelength λ N.

The optical diffraction module 20 includes a plurality of driving electrodes 22 electrically insulated from each other. The plurality of drive electrodes 22 are arranged in an array including a plurality of rows (X direction) and a plurality of columns (Y direction), the number of drive electrodes 22 in each row is equal, and the number of drive electrodes 22 in each column is equal. In this embodiment, a plurality of rows of driving electrodes 22 are arranged in each diffraction region 21. The respective drive electrodes 22 receive drive voltages independently of each other. By controlling the driving voltages on the rows of driving electrodes 22 in each diffraction region 21, the angle of the third light L3 emitted from each diffraction region 21, that is, the emitting direction of the third light L3 from each diffraction region 21, can be controlled, so that the third lights L3 are respectively guided to the corresponding output channels of the light transmission module 30 through the plurality of diffraction regions 21.

Referring to fig. 3, in the present embodiment, the optical transmission module 30 includes a plurality of output channels 31, and each output channel 31 is an optical fiber. The plurality of output channels 31 are arranged in the Y direction. That is, in the present embodiment, the arrangement of the plurality of output channels 31 is reverse perpendicular to the arrangement direction of the plurality of diffraction areas 21. Each output channel 31 is used for receiving at least one third light L3. That is, the output channels 31 do not correspond to the third lights L3. For an output channel 31, it may be used to receive one or more third lights L3. The amount of the third light L3 received by each output channel 31 and the wavelength of the third light L3 received by each output channel 31 are determined according to the optical path of the third light L3 output by the output channel 31. The present application does not limit the number and wavelength of the third light L3 received by each output channel 31.

Each third light L3 has a plurality of diffraction orders of-M \8230; -3, -2, -1,0, +1, +2, +3 \8230; + M. In fig. 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 for receiving 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 larger light utilization rate, in the present embodiment, the plurality of output channels 31 are used for receiving and outputting the +1 diffraction order of the plurality of third lights L3. That is, in the present embodiment, the target diffraction order of the plurality of output channels 31 is +1 diffraction order. In other embodiments, the target diffraction order may also be +2 diffraction order, and the light intensity of +2 diffraction order may be adjusted to reach the light intensity of +1 diffraction order or be slightly less than the light intensity of +1 diffraction order by setting the diffraction angle, so as to ensure a greater light utilization rate. The present application is not particularly limited to the selection of the target diffraction order.

Taking the output channel 311 as an example, for example, if the output channel 311 is used to receive the +1 diffraction order of the third light L3 with the wavelength λ 1, for the output channel 311, the +1 diffraction order of the third light L3 with the wavelength λ 1 is the signal light of the output channel 311, and the other diffraction orders of the third light L3 with the wavelength λ 1 and the third light L3 with the other wavelengths are crosstalk lights of the output channel 311. The same reason for dividing the signal light of the other output channels 31 into the crosstalk light is not repeated.

In order to improve the performance of the wavelength selective switch 100, for each output channel 31, signal light should be received as much as possible and crosstalk light should be prevented from being received as much as possible. While both signal light and crosstalk light have Insertion Loss (IL) when they enter the output channel 31, the larger the Insertion Loss, the more the light energy Loss when they enter, the smaller the Insertion Loss of the signal light and the larger the Insertion Loss of the crosstalk light, which is more advantageous for improving the performance of the wavelength selective switch 100. The difference in insertion loss between the signal light and the crosstalk light is defined as the degree of isolation. The higher the isolation, the better the performance of the wavelength selective switch 100.

Therefore, in the present embodiment, the isolation is improved from the following two aspects:

in the first aspect, the isolation is improved by reducing the insertion loss of the signal light.

In order 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 order of the third light L3 received thereby. That is, matching each output channel 31 with the mode field of the target diffraction order of the third light L3 received by it is beneficial to reduce the insertion loss of the signal light. Taking the output channel 311 as an example, the output channel 311 is used for receiving the +1 diffraction order of the third light L3 with the wavelength λ 1, and the mode field radius of the output channel 311 is set to be equal to the beam waist radius of the +1 diffraction order of the third light L3 with the wavelength λ 1, so that the mode field of the output channel 311 is matched with the mode field of the +1 diffraction order of the third light L3 with the wavelength λ 1, thereby reducing the insertion loss when the +1 diffraction order of the third light L3 with the wavelength λ 1 is coupled to the output channel 311.

In a second aspect, isolation is improved by increasing the insertion loss of crosstalk light.

In order to increase the insertion loss of crosstalk light, the mode field radius of each output channel 31 is set to be different from the beam waist radius of at least one kind of crosstalk light (crosstalk light having different wavelengths is considered as different kinds of crosstalk light, and light having different diffraction orders is also considered as different kinds of crosstalk light).

Taking the output channel 311 as an example, setting the mode field radius of the output channel 311 to be different from the beam waist radius of the at least one crosstalk light can make the mode field of the output channel 311 mismatched with that of the at least one crosstalk light, thereby increasing the insertion loss of the at least one crosstalk light incident on the output channel 311, i.e., making it difficult for the crosstalk light to be incident on the output channel 311.

In a modified embodiment of the present 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 the output channel 31 arranged adjacent to the mode field radius, or/and the mode field radius of each output channel 31 is set to be different from the beam waist radius of the diffraction orders other than the target diffraction order in the third light L3 received by the output channel 31. For each output channel 31, crosstalk light at a closer distance is more easily received and crosstalk light at a farther distance is less easily received. Therefore, increasing the insertion loss of crosstalk light at a short distance is more beneficial to efficiently improve the isolation. For each output channel 31, the crosstalk light at a short distance is the diffraction orders except the target diffraction order in the third light L3 received by the output channel 31 arranged adjacently and the third light L3 received by itself. Therefore, in the present 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 output channel 31 arranged adjacent to the mode field radius, or/and setting the mode field radius of each output channel 31 to be different from the beam waist radius of the diffraction orders other than the target diffraction order in the third light L3 received by the output channel 31, it is beneficial to efficiently improve the isolation.

In another modified embodiment of the present application, the mode field radius of each output channel 31 is different from the beam waist radius of any crosstalk light, so as to increase the insertion loss of each crosstalk light, thereby further improving the isolation.

Therefore, the wavelength selective switch 100 of the present embodiment is beneficial to improve the isolation and effectively improve the performance of 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.

For each output channel 31, its mode field radius depends on the material and structure of the fiber, so once the output channel is made, its mode field radius is not variable. In the present embodiment, the beam waist radius of the signal light and the beam waist radius of the crosstalk light are adjusted by adjusting the voltages applied to the respective driving electrodes 22 so that the signal light is mode-field matched with the output channel 31 and the crosstalk light is mode-field mismatched with the output channel 31.

When the driving voltage applied to each driving electrode 22 is changed, the beam waist radius of the third light L3 emitted from the light diffraction module 20 is changed. The correspondence between the value of the driving voltage and the value of the beam waist radius may be stored as a lookup table through experiments in advance or calculated according to an algorithm in advance, so that the corresponding value of the driving voltage may be queried and applied to each driving electrode 22 according to the required value of the beam waist radius during the operation of the wavelength selective switch 100.

The isolation, ω, is expressed by η ₁ And ω ₂ Respectively representing the beam waist radius of the third light L3 and the mode field radius of the output channel 31. The following formula is satisfied:

will omega ₁ And omega ₂ One of the two is set to obtain a curve of the variation of the isolation η with the other. For example, FIG. 4 shows the value of ω when ₁ And ω ₂ The variation of the isolation η with the value of the other at a value of 40 μm. In fig. 4, the horizontal axis represents the value of "another" and the vertical axis represents the isolation η. From FIG. 4, it can be seen that f ω is ₁ And ω ₂ The isolation η is minimum when one of the values is set to 40 micrometers and the isolation η is increased when the other value is also 40 micrometers, and the isolation η is increased when the other value deviates from 40 micrometers. The more the value of the other deviates from 40 μm, the more the isolation η increases. It can be seen that the isolation can be improved by setting the beam waist radius of the third light L3 equal to the mode field radius of the output channel 31.

Referring to fig. 3, in the present 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 configured to receive the first light L1 and transmit the first light L1 to the light splitting module 10. That is, in this embodiment, the first light L1 is input into the wavelength selective switch 100, and the third light L3 is output from the wavelength selective switch 100 through the optical transmission module 30, which is beneficial to reducing the overall size of the wavelength selective switch 100 and simplifying the optical path structure of the wavelength selective switch 100.

In this embodiment, the first light L1 includes light with multiple wavelengths, and since the light with multiple wavelengths is transmitted in the input channel 32, in order to reduce the insertion loss of the light with multiple wavelengths in the first light L1, the beam waist radii of the light with multiple wavelengths in the first light L1 are equal, and the beam waist radii of the light with multiple wavelengths in the first light L1 are equal to the mode field radius of the input channel 32, so as to improve the utilization rate of the light with multiple wavelengths in the first light L1.

For the light transmission module 30, the input channel 32 and the output channel 31 are both light transmission channels, and are substantially the same in structure, and depending on the light output direction, in other embodiments, the input channel 32 may also be used as the output channel 31, and the output channel 31 may also be used as the input channel 32. One optical transmission channel is embodied as an input channel or an output channel depending on the direction in which the optical transmission channel transmits light.

In this embodiment, the wavelength selective switch 100 further includes a plurality of lenses 40. The plurality of lenses 40 correspond one-to-one to the plurality of output channels 31. Each lens 40 is located between an output channel 31 and the light diffraction module 20. In the present embodiment, the curvature radius of each lens 40 is the same. Each lens 40 is used to focus the third light L3 to a corresponding output channel 31. So that the third light L3 is better coupled to the output channel 31, and the optical energy loss of the third light L3 is reduced.

In this embodiment, the wavelength selective switch 100 may further include other necessary elements, such as a polarizer for converting the first light L1 into linearly polarized light, a light guiding element (e.g., a reflective sheet, a cylindrical lens) for guiding the first light L1, the second light L2, and the third light L3 to transmit, and so on. The present application will be described primarily with reference to elements associated with the present application. Other elements will not be described in detail. In addition, the number of element structures shown in the drawings of the present embodiment is not intended to limit the present application, such as the number of driving electrodes 22 in each diffraction region 21 shown in fig. 2, or the number of output channels 31 and input channels 32 shown in fig. 3, and the like. The number of elements described above may vary in different embodiments and the figures are only examples.

In the wavelength selective switch 100 of the present embodiment, each output channel 31 is configured to receive at least one target diffraction order of the third light L3, and for each output channel 31, by setting the mode field radius of the output channel 31 to be equal to the beam waist radius of the target diffraction order of the at least one received third light L3, the insertion loss of the signal light of the output channel 31 can be reduced; by setting the mode field radius of the third light L3 to be unequal to the beam waist radius of at least one of the other diffraction orders except the target diffraction order, or/and setting the mode field radius of the third light L3 to be unequal to the beam waist radius of at least one of the other third light L3, the insertion loss of the crosstalk light of the output channel 31 can be increased. The isolation of the wavelength selective switch 100 can be improved by reducing the insertion loss of the signal light of the output channel 31 and increasing the insertion loss of the crosstalk light of the output channel 31.

Example two

Referring to fig. 5, the wavelength selective switch of the present embodiment is mainly different from the wavelength selective switch 100 of the first embodiment in that: the manner of adjusting the beam waist radius of the third light L3 is different. In this embodiment, the radius of the beam waist of the third light L3 is adjusted by adjusting the radius of curvature of each lens 40, instead of adjusting the radius of the beam waist of the third light L3 by adjusting the driving voltage on the driving electrode 22 in the first embodiment. The effect of the light diffraction module 20 on the second light L2 can be equivalent to a lens, and therefore, in the first embodiment, adjusting the driving voltage on each driving electrode 22 can also be regarded as being equivalent to adjusting the curvature radius of a lens.

When the curvature radius of the lens 40 is different, the beam waist radius of the third light L3 focused by the lens 40 can be different. In the present embodiment, the radius of curvature of each lens 40 is set so that the beam 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. Moreover, by setting the curvature radius of the at least one lens 40 to be different from the curvature radii of the other lenses 40, the beam waist radius of the target diffraction order of the third light L3 guided by the at least one lens 40 is different from the beam waist radii of the other third lights L3, that is, the beam waist radius of the other third lights L3 is different from the mode field radius of the output channel 31 corresponding to the at least one lens 40. The third light L3 guided by the at least one lens 40 can be mode field matched with the corresponding output channel 31, and the other third light L3 can be mode field mismatched with the corresponding output channel 31, so that the insertion loss of the signal light can be reduced, the insertion loss of the crosstalk light can be increased, and the isolation can be improved.

In a modified embodiment of the present embodiment, the curvature radii of the plurality of lenses 40 are different from each other, so that the beam waist radii of the third light L3 focused by the lenses 40 are different from each other, and thus the mode field radius of each output channel 31 is different from the beam waist radius of any crosstalk light, which can further increase the insertion loss of each crosstalk light, thereby being beneficial to further improving the isolation.

The wavelength selective switch of this embodiment can achieve all the advantages of the wavelength selective switch 100 in the first embodiment. On the basis, the present embodiment also provides a technical solution to adjust the radius of curvature of the plurality of lenses 40 instead of adjusting the driving voltage on the plurality of driving electrodes 22.

In an alternative embodiment of the present application, on the basis of adjusting the curvature radius of each lens 40, the adjustment of the beam waist radius of the signal light and the beam waist radius of the crosstalk light of each output channel 31 (that is, the adjustment of the beam waist radius of each third light L3) can be realized by adjusting the driving voltage applied to each driving electrode 22, so that the signal light is mode-field matched with the output channel 31, and the crosstalk light is mode-field mismatched with the output channel 31, thereby improving the isolation degree.

In another variation of the present application, on the basis of improving the isolation by using the principles of mode field matching and mode field mismatch, the isolation of the wavelength selective switch is further improved by using the principles of coherent cancellation and radial mismatch.

As mentioned above, in the present embodiment, each output channel 31 is configured to receive the +1 diffraction order of the one or more third lights L3, and the phases of the other diffraction orders of the third lights L3 can be adjusted by adjusting the driving voltages on the respective driving electrodes 22, so that the other diffraction orders except for the +1 diffraction order in each third light L3 at least partially cancel each other, and the coupling amount of the diffraction orders except for the +1 diffraction order in the third light L3 to the output channel 31 is reduced. That is, crosstalk light is reduced in a coherent cancellation mode, insertion loss of the crosstalk light is increased, and the isolation is favorably improved. Whereas for radial mismatch this can be achieved by increasing the spacing between the individual output channels 31.

Therefore, the above-mentioned another modified embodiment is also beneficial to further improving the isolation of the wavelength selective switch on the basis of realizing the above-mentioned beneficial effects.

EXAMPLE III

The wavelength selective switch of this embodiment is different from the wavelength selective switch of the first embodiment mainly in that the arrangement of the output channels 31 and the input channels 32 is different.

Referring to fig. 6, in the present embodiment, the optical transmission module 30 includes a plurality of output channels 31 and an input channel 32.

In the first embodiment, the input channel 32 and the plurality of output channels 31 are arranged in parallel, and the input channel is located on the same side of the plurality of output channels 31. That is, in the first embodiment, the optical transmission module 30 includes a plurality of optical transmission channels arranged in parallel, wherein one of the leftmost optical transmission channel and the rightmost optical transmission channel serves as the optical input channel 32.

In the present embodiment, the input channel 32 and the plurality of output channels 31 are arranged in parallel, and the plurality of output channels 31 are respectively located at two sides of the input channel 32. That is, with the orientation of fig. 6 as a reference, in the present embodiment, a part of the output channels 31 is located on the left side of the input channels 32, and another part of the output channels 31 is located on the right side of the input channels 32. And in this embodiment, the number of output channels 31 on the left and right sides of the input channel 32 is equal. In an alternative embodiment of the present embodiment, the number of output channels 31 on the left and right sides of the input channel 32 may be different.

The wavelength selective switch of the embodiment can achieve all the beneficial effects of the wavelength selective switch 100 of the embodiment, so the isolation of the wavelength selective switch of the embodiment is effectively improved. On the basis of the improvement of the isolation of the wavelength selective switch, the crosstalk between the output channels 31 is reduced, and the wavelength selective switch in this embodiment may be set to implement "double-sided diffraction". That is, in the present embodiment, the plurality of output channels 31 are respectively located at two sides of the input channel 32, the third light L3 is output from the output channels 31 at two sides of the input channel 32, and in the present embodiment, the target diffraction order includes two diffraction orders: the +1 diffraction order and the-1 diffraction order, the +1 diffraction order and the-1 diffraction order are output from the output channels 31 on the left and right sides of the input channel 32, respectively.

The wavelength selective switch of the embodiment employs the above-mentioned "bilateral diffraction", so that the distance between the plurality of output channels 31 and the input channel 32 can be effectively reduced, thereby facilitating to improve the integration level of the wavelength selective switch.

In this embodiment, the arrangement of the input channel 32 and the plurality of output channels 31 can also be applied to the second embodiment, and the same technical effects can also be achieved.

It will be appreciated by those skilled in the art that the above embodiments are illustrative only and not intended to be limiting, and that suitable modifications and variations may be made to the above embodiments without departing from the true spirit and scope of the invention.

Claims

1. A wavelength selective switch, comprising:

the light diffraction module is positioned on the light path of the plurality of second lights and is used for receiving and diffracting the plurality of second lights to emit a plurality of third lights, the light diffraction module comprises a plurality of diffraction areas, the plurality of diffraction areas are in one-to-one correspondence with the plurality of second lights, and each diffraction area is used for diffracting the corresponding second light and emitting one third light; and

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

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

3. The wavelength selective switch of claim 1, further comprising a plurality of lenses between the optical diffraction module and the optical transmission module, the plurality of lenses in one-to-one correspondence with the plurality of output channels;

each lens is used for receiving the target diffraction order of the at least one beam of third light and focusing the target diffraction order to the corresponding output channel.

4. The wavelength selective switch of claim 3, wherein the radii of curvature of the plurality of lenses are equal.

5. The wavelength selective switch of claim 3, wherein at least one lens has a radius of curvature that is different from the radius of curvature of the other lenses.

6. The wavelength selective switch of claim 5, wherein the radii of curvature of the plurality of lenses are mutually different.

7. The wavelength selective switch according to any one of claims 1 to 6, wherein the light diffraction module is a liquid crystal on silicon, and the beam waist radii of the respective diffraction orders of the plurality of third lights are respectively adjusted by respectively adjusting driving voltages applied to the plurality of diffraction regions.

8. The wavelength selective switch of any one of claims 1-7, wherein the target diffraction order comprises one diffraction order.

9. The wavelength selective switch of claim 8, wherein the target diffraction order is a +1 diffraction order.

10. The wavelength selective switch of any one of claims 1-7, wherein the target diffraction order comprises two diffraction orders.

11. The wavelength selective switch of claim 10, wherein the target diffraction orders comprise a +1 diffraction order and a-1 diffraction order.

12. The wavelength selective switch of any one of claims 1-11, wherein the optical transmission module further comprises an input channel for receiving the first light and transmitting the first light to the optical splitting module.

13. The wavelength selective switch of any one of claims 1-12, wherein the beam waist radii of each of the wavelengths of the first light are equal.