A stray light suppression device and a stray light suppression structure for a photonic chip

Abstract

This invention relates to a stray light suppression device and structure for photonic chips, belonging to the field of optical sensing technology, and solves the problem of reduced signal-to-noise ratio caused by stray light crosstalk in photonic chip circuits. The stray light suppression device includes a stray light suppressor and a stray light absorption layer. The stray light suppressor includes a first inverted conical waveguide, a straight waveguide, and a vertical diffraction grating structure. The stray light absorption layer is located on the upper and lower surfaces of the photonic chip and covers the vertical diffraction grating structure in the vertical direction. The first inverted conical waveguide and the straight waveguide are used to directionally guide stray light in the photonic chip, the vertical diffraction grating structure is used to diffract the directionally guided stray light to the upper and lower surfaces of the photonic chip, and the stray light absorption layer is used to absorb the diffracted and radiated stray light in the photonic chip.

Description

Technical Field

[0001] This invention relates to the field of optical sensing technology, and in particular to a stray light suppression device and structure for photonic chips. Background Technology

[0002] Photonic chips typically consist of active and passive components, using optical waveguides as the core transmission medium to achieve functions such as optical signal transmission, beam splitting, coupling, and modulation. Due to their high integration, mass production capability, low cost, and low power consumption, photonic chips have been widely used in optical sensing, optical communication, and optical computing. However, with the rapid development of emerging technologies such as autonomous driving, artificial intelligence, and quantum computing, stringent requirements have been placed on the performance, accuracy, and stability of photonic chips. In existing photonic chip structures, key components such as optical beamsplitters, bent cascaded polarizers, and end-face couplers are prone to generating stray light during operation, causing crosstalk between on-chip optical paths. This stray light interference not only reduces the signal-to-noise ratio but can also distort the output signal of the photonic chip, severely affecting the overall performance and reliability of the system.

[0003] Currently, there is a lack of efficient and feasible methods to effectively suppress this problem. Therefore, how to propose and design a feasible stray light suppression scheme has become a pressing technical challenge to be solved in the realization of high-performance, high-precision photonic chips, and will also greatly affect their further promotion and development in high-end application scenarios. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a stray light suppression device and a stray light suppression structure for photonic chips, so as to solve the problem of reduced signal-to-noise ratio caused by stray light crosstalk in photonic chip circuits.

[0005] In a first aspect, embodiments of the present invention provide a stray light suppression device for a photonic chip, comprising:

[0006] Stray light suppressor and stray light absorption layer;

[0007] The stray light suppressor includes a first inverted conical waveguide, a straight waveguide, and a vertical diffraction grating structure. The stray light absorption layer is located on the upper and lower surfaces of the photonic chip and covers the vertical diffraction grating structure in the vertical direction.

[0008] The first inverted conical waveguide and the straight waveguide are used to guide stray light in the photonic chip in a specific direction. The straight waveguide is a waveguide that extends a certain length along the widest part of the first inverted conical waveguide. The vertical diffraction grating structure is used to diffract the guided stray light to the upper and lower surfaces of the photonic chip. The stray light absorption layer is used to absorb the diffracted and radiated stray light in the photonic chip.

[0009] Based on further improvements to the above-mentioned device, the stray light suppressor also includes:

[0010] The second and third inverted conical waveguides are located on either side of the first inverted conical waveguide, respectively;

[0011] The second and third inverted conical waveguides are used to focus stray light from the photonic chip onto the first inverted conical waveguide.

[0012] Based on further improvements to the above-mentioned device, the first inverted conical waveguide, the second inverted conical waveguide, and the third inverted conical waveguide are trident-shaped.

[0013] Based on further improvements to the above-mentioned device, the light-absorbing material of the stray light-absorbing layer is a metal or an absorbent adhesive.

[0014] Secondly, embodiments of the present invention provide a stray light suppression structure, comprising:

[0015] At least one stray light suppression device for a photonic chip according to any one of the first aspects of the present invention, or at least one stray light suppression cascade structure, wherein the stray light suppression cascade structure comprises at least two cascaded stray light suppression devices for a photonic chip according to any one of the first aspects of the present invention.

[0016] The at least one stray light suppression device or the at least one stray light suppression cascade structure is distributed on the output straight waveguide side of the multimode interference coupler.

[0017] Further improvements to the above stray light suppression structure include:

[0018] Multiple stray light suppression devices or multiple stray light suppression cascade structures are symmetrically distributed on both sides of the output straight waveguide of the multimode interference coupler, and the multiple stray light suppression devices or multiple stray light suppression cascade structures are distributed on one side of the output straight waveguide of the multimode interference coupler with tilt angles of 45°, 30° and 15° respectively.

[0019] Thirdly, embodiments of the present invention provide a stray light suppression structure, comprising:

[0020] At least one stray light suppression device for a photonic chip according to any one of the first aspects of the present invention, or at least one stray light suppression cascade structure, wherein the stray light suppression cascade structure comprises at least two cascaded stray light suppression devices for a photonic chip according to any one of the first aspects of the present invention.

[0021] The at least one stray light suppression device or the at least one stray light suppression cascade structure is distributed along the tangent direction of the curved waveguide in the curved cascade polarizer.

[0022] Fourthly, embodiments of the present invention provide a stray light suppression structure, comprising:

[0023] The stray light absorbing adhesive coating and at least one stray light suppression device for a photonic chip according to any one of the first aspects of the invention, or at least one stray light suppression cascade structure, wherein the stray light suppression cascade structure comprises at least two cascaded stray light suppression devices for a photonic chip according to any one of the first aspects of the invention, wherein the stray light absorbing adhesive coating is located on the upper and lower surfaces of the photonic chip and the stray light absorbing adhesive coating covers the tapered end face of the tapered end face coupler in the vertical direction;

[0024] The at least one stray light suppression device or the at least one stray light suppression cascade structure is distributed on both sides of the tapered end face of the tapered end face coupler.

[0025] Fifthly, an embodiment of the present invention provides a stray light suppression structure, comprising:

[0026] At least one stray light suppression device for a photonic chip according to any one of the first aspects of the present invention, or at least one stray light suppression cascade structure, wherein the stray light suppression cascade structure comprises at least two cascaded stray light suppression devices for a photonic chip according to any one of the first aspects of the present invention.

[0027] The at least one stray light suppression device or the at least one stray light suppression cascade structure is arranged in a regular pattern.

[0028] Based on the further improvement of the above stray light suppression structure, the regular pattern is a circle or a rectangle.

[0029] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0030] 1. This invention can significantly reduce the problems of signal-to-noise ratio reduction, signal accuracy reduction, and output signal distortion caused by stray light in the photonic chip circuit, and effectively improve the reliability and overall performance of photonic devices and systems.

[0031] 2. This invention has significant advantages in terms of structural integration, stray light suppression efficiency, and manufacturing compatibility, providing a feasible technical path for the design of high-precision and high-stability photonic chips, and has good application prospects and promotion value.

[0032] 3. This invention combines a trident coupler with a vertical diffraction grating, which can effectively guide stray light to a specific region. This invention can guide stray light towards the material absorption layer in the chip, thereby achieving controllable dissipation of light energy; this invention not only enables directional control of stray light but also enhances the stability and reliability of photonic chips in complex optical path environments.

[0033] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0034] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0035] Figure 1 A schematic diagram of a stray light suppression device for a photonic chip according to an embodiment of the present invention is shown.

[0036] Figure 2 It shows Figure 1 A cross-sectional view of the photonic chip 10 in the image.

[0037] Figure 3 A schematic diagram of a stray light suppression structure for a 2×1 multimode interference coupler in a photonic chip according to an embodiment of the present invention is shown.

[0038] Figure 4 A schematic diagram of a stray light suppression structure for a bent cascade polarizer in a photonic chip according to an embodiment of the present invention is shown.

[0039] Figure 5 A schematic diagram of a stray light suppression structure for a tapered end-face coupler in a photonic chip according to an embodiment of the present invention is shown.

[0040] Figure 6 A schematic diagram of a stray light suppression structure for blank areas in a photonic chip according to an embodiment of the present invention is shown. Detailed Implementation

[0041] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0042] According to one aspect of the present invention, a stray light suppression device for a photonic chip is provided. Figure 1 A schematic diagram of a stray light suppression device for a photonic chip according to an embodiment of the present invention is shown. Figure 1 As shown, the stray light suppression device for the photonic chip 10 includes a stray light suppressor and a stray light absorption layer 400. The stray light suppressor includes a first inverted conical waveguide 100, a straight waveguide 200, and a vertical diffraction grating structure 300. The stray light absorption layer 400 is located on the upper and lower surfaces of the photonic chip 10, and the stray light absorption layer 400 covers the vertical diffraction grating structure 300 in the vertical direction.

[0043] In this embodiment, the first inverted conical waveguide 100 and the straight waveguide 200 are used to guide stray light in the photonic chip 10. The straight waveguide 200 is a waveguide extending a certain length along the widest part of the first inverted conical waveguide 100. The vertical diffraction grating structure 300 is used to diffract the guided stray light onto the upper and lower surfaces of the photonic chip 10. The stray light absorption layer 400 is used to absorb the diffracted and radiated stray light in the photonic chip 10.

[0044] Figure 2 It shows Figure 1 A cross-sectional view of the photonic chip 10 in the image. (See image for details.) Figure 2 As shown, the photonic chip 10 includes a first stray light absorption layer 201, a cladding layer 202, a core layer 203, a substrate 204, and a second stray light absorption layer 205. A stray light suppressor is located within the core layer 203. The stray light absorption layer 400 includes a first stray light absorption layer 201 located on the upper surface of the photonic chip 10 and a second stray light absorption layer 205 located on the lower surface of the photonic chip 10.

[0045] In some embodiments, Figure 1 The stray light suppressor also includes a second inverted conical waveguide 500 and a third inverted conical waveguide 600 located on either side of the first inverted conical waveguide 100. The second inverted conical waveguide 500 and the third inverted conical waveguide 600 are used to focus stray light from the photonic chip 10 onto the first inverted conical waveguide 100. The second inverted conical waveguide 500 and the third inverted conical waveguide 600 do not have straight waveguides.

[0046] In some embodiments, the first inverted conical waveguide 100, the second inverted conical waveguide 500, and the third inverted conical waveguide 600 form a trident shape. The first inverted conical waveguide 100, the second inverted conical waveguide 500, and the third inverted conical waveguide 600 can be any waveguide material, such as silicon nitride, lithium niobate, etc.

[0047] In some embodiments, the light-absorbing material of the stray light-absorbing layer 400 is a metal or an absorbent adhesive.

[0048] In some embodiments, the width of the first inverted conical waveguide 100 is 300±20 nanometers and the length is 50±2 micrometers; the width of the straight waveguide 200 is 1±0.2 micrometers and the length is 20±2 micrometers; the vertical diffraction grating structure 300 has a vertical diffraction grating period of 1.5±0.2 micrometers, a duty cycle of 0.5, and a diffraction efficiency >50%. The width at the widest point of the first inverted conical waveguide 100 is the same as that of the straight waveguide 200.

[0049] In some embodiments, the second inverted conical waveguide 500 and the third inverted conical waveguide 600 have the same structure, and the width of the second inverted conical waveguide 500 or the third inverted conical waveguide 600 is 300 nanometers and the length is 20 micrometers. In this embodiment, the width of the inverted conical structure (including the first inverted conical waveguide 100, the second inverted conical waveguide 500 and the third inverted conical waveguide 600) refers to the width at the narrowest point of the inverted conical structure.

[0050] According to another aspect of the present invention, a stray light suppression structure is provided for use in a multimode interference coupler in a photonic chip. Figure 3 A schematic diagram of a stray light suppression structure for a 2×1 multimode interference coupler in a photonic chip according to an embodiment of the present invention is shown.

[0051] like Figure 3 As shown, the waveguide mainly consists of input straight waveguide 1-1, input straight waveguide 2-2, multimode interference coupling cone 1-3, multimode interference coupling cone 2-4, multimode interference region 1-5, multimode interference coupling cone 3-6, output straight waveguide 1-7, stray light suppressor 1-8, stray light suppressor 2-9, stray light suppressor 3-10, stray light suppressor 4-11, stray light suppressor 5-12, stray light suppressor 6-13, and stray light absorption layer 3-14.

[0052] The incident light passes through input straight waveguide 1-1 and multimode interference coupling cone 1-3, and is coupled into multimode interference region 1-5. After multimode interference, it passes through multimode interference coupling cone 3-6 and is transmitted to output straight waveguide 1-7. The incident light interferes in multimode interference region 1-5, and after passing through multimode interference coupling cone 3-6, it generates inherent loss and dissipates in the form of radiation modes, forming stray light. The stray light is guided to the upper surface of the chip by stray light suppressors 1-8, 1-9, 1-10, 1-11, 1-12, and 1-13, and is absorbed and dissipated by stray light absorption layer 1-14. Stray light suppressors 1-8, 2-9, 3-10, 4-11, 5-12, and 6-13 can be based on the information in this paper. Figure 1 Stray light suppressor of any of the embodiments described.

[0053] In some preferred embodiments, a stray light absorption layer 1-14 can be configured at the position of the third multimode interference coupling cone 1-6 to absorb stray light radiated by the third multimode interference coupling cone 1-6. Since the third multimode interference coupling cone 1-6 is prone to generating stray light, this configuration can further improve the stray light absorption rate.

[0054] In some embodiments, the width of input straight waveguide 1-1, input straight waveguide 1-2, and output straight waveguide 1-7 is 1 micrometer, and the length is 20 micrometers; the width of the inverted cone of multimode interference coupling cone 1-3, multimode interference coupling cone 1-4, and multimode interference coupling cone 1-6 is 4 micrometers, and the length is 200 micrometers; the width of multimode interference region 1-5 is 12 micrometers, and the length is 122 micrometers.

[0055] In some preferred embodiments, stray light suppressors 1-8, 2-9, and 3-10 are distributed on one side of output straight waveguide 1-7 with tilt angles of 45°, 30°, and 15°, respectively, while stray light suppressors 1-11, 5-12, and 6-13 are distributed on the other side of output straight waveguide 1-7 with tilt angles of -45°, -30°, and -15°, respectively.

[0056] According to another aspect of the present invention, a stray light suppression structure is provided for use in a bent cascade polarizer in a photonic chip. Figure 4 A schematic diagram of a stray light suppression structure for a bent cascade polarizer in a photonic chip according to an embodiment of the present invention is shown.

[0057] like Figure 4As shown, the waveguide mainly consists of input straight waveguide 2-1 (No. 3), 1 / 4 circular curved waveguide 2-2 (No. 1), 1 / 2 circular curved waveguide 2-3 (No. 1), 1 / 2 circular curved waveguide 2-4 (No. 2), 1 / 4 circular curved waveguide 2-5 (No. 2), output straight waveguide 2-6 (No. 2), stray light suppressor 2-7 (No. 7), stray light suppressor 2-8 (No. 8), stray light suppressor 2-9 (No. 9), stray light suppressor 2-10 (No. 10), stray light suppressor 2-11 (No. 11), stray light suppressor 2-12 (No. 12), and stray light absorption layer 2-13 (No. 4).

[0058] The incident light passes through input straight waveguide 2-1 (No. 3), 1 / 4 circular curved waveguide 2-2 (No. 1), 1 / 2 circular curved waveguide 2-3 (No. 1), 1 / 2 circular curved waveguide 2-4 (No. 2), and 1 / 4 circular curved waveguide 2-5 (No. 2), and is transmitted to output straight waveguide 2-6 (No. 2). Stray light is generated in the region of 1 / 4 circular curved waveguide 2-2 (No. 1), 1 / 2 circular curved waveguide 2-3 (No. 1), 1 / 2 circular curved waveguide 2-4 (No. 2), and 1 / 4 circular curved waveguide 2-5 (No. 2). This stray light is guided to the upper and lower surfaces of the chip by stray light suppressors 2-7 (No. 7), 2-8 (No. 8), 2-9 (No. 9), 2-10 (No. 10), 2-11 (No. 11), and 2-12 (No. 12), and is absorbed and dissipated by stray light absorption layer 2-13 (No. 4). Stray light suppressors 2-7 (No. 7), 2-8 (No. 8), 2-9 (No. 9), 2-10 (No. 10), 2-11 (No. 11), and 2-12 (No. 12) can be based on the information presented in this paper. Figure 1 Stray light suppressor of any of the embodiments described.

[0059] In some preferred embodiments, a stray light absorption layer 2-13 can be installed at positions 1 / 4-circular curved waveguide 2-2, 1 / 2-circular curved waveguide 2-3, 2 / 2-circular curved waveguide 2-4, and 2 / 4-circular curved waveguide 2-5 to absorb stray light radiated from these waveguides. Since stray light is easily generated at these waveguides, this configuration can further improve the stray light absorption rate.

[0060] In some embodiments, the width of input straight waveguide 2-1 (No. 3) and output straight waveguide 2-6 (No. 2) is 1 micrometer and the length is 20 micrometers; the bending radius of 1 / 4 circular curved waveguide 2-2, 1 / 2 circular curved waveguide 2-3, 2 / 2 circular curved waveguide 2-4, and 2 / 4 circular curved waveguide 2-5 is 50 micrometers.

[0061] In some embodiments, stray light suppressors 2-7 (No. 7), 2-8 (No. 8), 2-9 (No. 9), 2-10 (No. 10), 2-11 (No. 11), and 2-12 (No. 12) are distributed along the tangent direction of the curved waveguide. Preferably, they can be distributed along the tangent direction of the curved waveguide tangent of the 1 / 4 circular curved waveguide 2-2 and the 2 / 4 circular curved waveguide 2-5. This document is based on... Figure 1 Stray light suppressor of any of the embodiments described.

[0062] According to another aspect of the present invention, a stray light suppression structure is provided for use in a tapered end-face coupler in a photonic chip. Figure 5 A schematic diagram of a stray light suppression structure for a tapered end-face coupler in a photonic chip according to an embodiment of the present invention is shown.

[0063] like Figure 5 As shown, the waveguide mainly consists of input straight waveguide 4 (3-1), tapered end coupler 3-2, output straight waveguide 3 (3-3), stray light suppression cascade structure 1 (3-4), stray light suppression cascade structure 2 (3-5), stray light suppression cascade structure 3 (3-6), stray light suppression cascade structure 4 (3-7), stray light suppression cascade structure 5 (3-8), stray light suppression cascade structure 6 (3-9), and stray light absorbing adhesive coating 3-10.

[0064] The incident light enters the tapered end-face coupler 3-2 through input straight waveguide 3-1 (No. 4) and then exits through output straight waveguide 3-3 (No. 3). The incident light couples with the external optical fiber through the tapered end-face coupler 3-2. Due to mode mismatch at the coupling interface, back-reflected light is generated. Furthermore, minor process defects on the end face of the tapered end-face coupler 3-2 can lead to backscattered light, thus forming additional stray light. The stray light is guided to the upper and lower surfaces of the chip through stray light suppression cascade structures 3-4 (No. 1), 3-5 (No. 2), 3-6 (No. 3), 3-7 (No. 4), 3-8 (No. 5), and 3-9 (No. 6), where it is absorbed and dissipated by the stray light absorbing adhesive coating 3-10. Each stray light suppression cascade structure consists of two stray light suppressors connected in series. Simulation results show that the two stray light suppressors connected in series can improve the stray light guiding diffraction efficiency to more than 75%.

[0065] In this embodiment, the stray light suppression cascade structure can be multiple cascaded stray light suppressors, and the stray light suppressors can be those described herein. Figure 1 Stray light suppressor of any embodiment described. It should be noted that, although... Figure 5The stray light suppression cascade structure shown consists of two cascaded stray light suppressors, but the present invention is not limited to this; any other number of cascaded stray light suppressors fall within the scope of protection of this invention. Furthermore, although... Figure 3 and Figure 4 The stray light suppressor shown is a single stray light suppressor, but the present invention is not limited thereto. Figure 3 and Figure 4 Any of the stray light suppressors shown can be replaced with Figure 5 The stray light suppression cascade structure shown in the figure.

[0066] In some embodiments, the width of input straight waveguide 3-1 (No. 4) and output straight waveguide 3-3 (No. 3) is 1 micrometer and the length is 20 micrometers; the width of tapered end coupler 3-2 is 250 nanometers and the length is 300 micrometers.

[0067] According to another aspect of the present invention, a stray light suppression structure is provided for use in blank areas of a photonic chip. Figure 6 A schematic diagram of a stray light suppression structure for blank areas in a photonic chip according to an embodiment of the present invention is shown.

[0068] like Figure 6 As shown, a stray light suppressor array can be distributed in the blank area of ​​the photonic chip. The stray light suppressor array consists of multiple stray light suppressors, which can be arranged in a circular, rectangular or other regular shape.

[0069] Although the stray light suppressor shown in 6 is a single stray light suppressor, the present invention is not limited thereto. Figure 6 Any of the stray light suppressors shown can be replaced with Figure 5 The stray light suppression cascade structure shown in the figure.

[0070] In this embodiment, the astigmatism suppressor array is placed in any blank area of ​​the chip that is not occupied by functional devices, so as to effectively capture and absorb stray light from different propagation directions, thereby improving the overall stability of the device.

[0071] Compared with the prior art, the embodiments of the present invention can achieve at least one of the following beneficial effects:

[0072] 1. This invention can significantly reduce the problems of signal-to-noise ratio reduction, signal accuracy reduction, and output signal distortion caused by stray light in the photonic chip circuit, and effectively improve the reliability and overall performance of photonic devices and systems.

[0073] 2. This invention has significant advantages in terms of structural integration, stray light suppression efficiency, and manufacturing compatibility, providing a feasible technical path for the design of high-precision and high-stability photonic chips, and has good application prospects and promotion value.

[0074] 3. This invention combines a trident coupler with a vertical diffraction grating, which can effectively guide stray light to a specific region. This invention can guide stray light towards the material absorption layer in the chip, thereby achieving controllable dissipation of light energy; this invention not only enables directional control of stray light but also enhances the stability and reliability of photonic chips in complex optical path environments.

[0075] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A stray light suppression device for a photonic chip, characterized in that, include: Stray light suppressor and stray light absorption layer; The stray light suppressor includes a first inverted conical waveguide, a straight waveguide, and a vertical diffraction grating structure. The stray light absorption layer is located on the upper and lower surfaces of the photonic chip and covers the vertical diffraction grating structure in the vertical direction. The first inverted conical waveguide and the straight waveguide are used to guide stray light in the photonic chip in a specific direction. The straight waveguide is a waveguide that extends a certain length along the widest part of the first inverted conical waveguide. The vertical diffraction grating structure is used to diffract the guided stray light to the upper and lower surfaces of the photonic chip. The stray light absorption layer is used to absorb the stray light diffracted and radiated in the photonic chip. The stray light suppressor further includes a second inverted conical waveguide and a third inverted conical waveguide located on both sides of the first inverted conical waveguide. The second inverted conical waveguide and the third inverted conical waveguide are used to converge stray light in the photonic chip to the first inverted conical waveguide. The first inverted conical waveguide, the second inverted conical waveguide and the third inverted conical waveguide are trident-shaped, and the second inverted conical waveguide and the third inverted conical waveguide have the same structure.

2. The apparatus according to claim 1, characterized in that, The light-absorbing material of the stray light-absorbing layer is a metal or an absorbent adhesive.

3. A stray light suppression structure, characterized in that it is used for... Multimode interference couplers in photonic chips; including: At least one stray light suppression device for a photonic chip according to any one of claims 1 to 2, or at least one stray light suppression cascade structure, wherein the stray light suppression cascade structure comprises at least two cascaded stray light suppression devices for a photonic chip according to any one of claims 1 to 2. The at least one stray light suppression device or the at least one stray light suppression cascade structure is distributed on the output straight waveguide side of the multimode interference coupler.

4. The stray light suppression structure according to claim 3, characterized in that, include: Multiple stray light suppression devices or multiple stray light suppression cascade structures are symmetrically distributed on both sides of the output straight waveguide of the multimode interference coupler, and the multiple stray light suppression devices or multiple stray light suppression cascade structures are distributed on one side of the output straight waveguide of the multimode interference coupler with tilt angles of 45°, 30° and 15° respectively.

5. A stray light suppression structure, characterized in that, Used in bent cascaded polarizers in photonic chips; including: At least one stray light suppression device for a photonic chip according to any one of claims 1 to 2, or at least one stray light suppression cascade structure, wherein the stray light suppression cascade structure comprises at least two cascaded stray light suppression devices for a photonic chip according to any one of claims 1 to 2. The at least one stray light suppression device or the at least one stray light suppression cascade structure is distributed along the tangent direction of the curved waveguide in the curved cascade polarizer.

6. A stray light suppression structure, characterized in that, Tapered end-face couplers for use in photonic chips; including: The stray light absorbing adhesive coating and at least one stray light suppression device for a photonic chip according to any one of claims 1 to 2, or at least one stray light suppression cascade structure, wherein the stray light suppression cascade structure comprises at least two cascaded stray light suppression devices for a photonic chip according to any one of claims 1 to 2, wherein the stray light absorbing adhesive coating is located on the upper and lower surfaces of the photonic chip and the stray light absorbing adhesive coating covers the tapered end face of the tapered end face coupler in the vertical direction; The at least one stray light suppression device or the at least one stray light suppression cascade structure is distributed on both sides of the tapered end face of the tapered end face coupler.

7. A stray light suppression structure, characterized in that, Used for blank areas in photonic chips; including: At least one stray light suppression device for a photonic chip according to any one of claims 1 to 2, or at least one stray light suppression cascade structure, wherein the stray light suppression cascade structure comprises at least two cascaded stray light suppression devices for a photonic chip according to any one of claims 1 to 2. The at least one stray light suppression device or the at least one stray light suppression cascade structure is arranged in a regular pattern.

8. The stray light suppression structure according to claim 7, characterized in that, The regular shape is either a circle or a rectangle.

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