Dispersion compensation annular reflector and preparation method thereof

Abstract

The invention relates to a dispersion compensation annular reflector and a preparation method thereof. Comprising a substrate, a silicon waveguide core layer arranged on the substrate, and a first 1 * 2 multimode interferometer, a first bent conical waveguide, a second bent conical waveguide, a first mode converter, a second mode converter and a first coupling waveguide which are arranged on the silicon waveguide core layer, the first end and the second end of the first 1 * 2 multi-mode interferometer are respectively provided with a port and two ports, and the port of the first end is connected to the section of the incident and emergent waveguide through the first single-mode waveguide; the two ports of the second end are connected to the input ends of the first mode converter and the second mode converter through the first bent conical waveguide and the second bent conical waveguide respectively, and the output ends of the first mode converter and the second mode converter are connected through the first coupling waveguide. The device provided by the invention can be adapted to various material platforms, and has good integration with other devices.

Description

Technical Field

[0001] The present invention relates to the technical field of photon integrated chips, and more specifically, to a dispersion compensating annular reflector and a preparation method thereof. Background Art

[0002] The characteristic absorption peaks of most molecular bonds (such as CO, NH, CH, etc.) are concentrated in the mid-infrared band, so the mid-infrared band has important application value in the field of molecular absorption spectral sensing. By making the optical system chip-based, not only can the system be made more compact and reliable, but also the power consumption and optical loss can be significantly reduced. The integration of on-chip sensing systems in the mid-infrared band has broad application prospects, covering multiple directions such as portable spectrometers, military fields, and biological detection.

[0003] The core of the on-chip spectral sensing system is a light source with a wide spectral range. The optical frequency comb generated based on nonlinear effects has great potential due to its wide spectrum, especially in dual optical frequency comb sensing applications. Therefore, the efficient generation of mid-infrared optical frequency combs has become one of the current research hotspots. According to existing research results, whether it is an efficient Kerr optical frequency comb, a supercontinuum spectrum, or a quantum cascade laser optical frequency comb, the key condition of a small and flat negative group velocity dispersion must be met in the resonant cavity. However, since the intracavity dispersion often cannot meet this requirement, an additional dispersion compensation mechanism must be introduced. Therefore, it is of great scientific significance and practical value to study devices that can achieve dispersion compensation for optical frequency combs.

[0004] Dispersion compensation can be achieved through the following methods: (1) Adjusting the geometric structure of the optical waveguide: The dispersion characteristics are adjusted by changing the geometric dimensions of the waveguide (such as width). However, for a given wafer, the waveguide thickness is fixed, and dispersion compensation can only be achieved by adjusting the waveguide width, which has limited adjustment capabilities. (2) Chirped Bragg grating: Dispersion compensation is achieved by changing the grating width or designing a specific working wavelength. However, this method requires the introduction of a fine grating structure, which has high requirements for processing technology, increasing manufacturing complexity and cost. (3) Coupled waveguides: Dispersion compensation is achieved by exciting specific coupling modes. This method is simple and efficient in design, and is applicable to a variety of material platforms and has good versatility. However, coupled waveguides are difficult to integrate on-chip with other devices, which to a certain extent limits its application scenarios. Overall, the current dispersion compensation technologies have their own advantages and disadvantages, but how to meet the integration requirements of on-chip photonic systems while ensuring design efficiency and manufacturing feasibility remains a challenge. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiency of the prior art that coupled waveguides are difficult to integrate on-chip with other devices, and to provide a dispersion-compensating annular reflector and a preparation method thereof, which can be adapted to a variety of material platforms and have good integration with other devices.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] Provided is a dispersion-compensating annular reflector, comprising a substrate, a silicon waveguide core layer arranged on the substrate, and a first 1×2 multimode interferometer, a first curved tapered waveguide, a second curved tapered waveguide, a first mode converter, a second mode converter and a first coupling waveguide arranged on the silicon waveguide core layer; a first end and a second end of the first 1×2 multimode interferometer are respectively provided with one port and two ports, the port at the first end is connected to an incident and an output waveguide section through a first single-mode waveguide, and the incident and output waveguide sections are the same section; two ports at the second end are respectively connected to the input ends of the first mode converter and the second mode converter through the first curved tapered waveguide and the second curved tapered waveguide, and the output ends of the first mode converter and the second mode converter are connected through the first coupling waveguide.

[0008] The present invention provides a dispersion-compensating annular reflector, wherein a first 1×2 multimode interferometer is used to realize 50:50 optical power splitting and combining; after the light input to the first 1×2 multimode interferometer is evenly divided into two beams, the fundamental mode excitation is converted into a specific coupling mode through the first mode converter and the second mode converter respectively; after the two beams realize the dispersion compensation function in the first coupling waveguide, the specific coupling mode is converted back to the fundamental mode through the second mode converter and the first mode converter respectively, and the light is combined in the first 1×2 multimode interferometer, and finally output from the first port of the first 1x2 multimode interferometer, thereby completing the dispersion compensation and optical feedback functions. A dispersion-compensating annular reflector provided by the present invention has both dispersion compensation and optical feedback functions, is simple in design, and effectively reduces process requirements; the coupled waveguide structure is universal and can be adapted to a variety of material platforms (such as silicon-based, silicon nitride-based, lithium niobate, etc.), expanding the application scope of the present invention in different on-chip photonic integrated systems; it has good integration with other devices, and the structural design of the present invention supports on-chip integration with other photonic devices (such as multi-mode interferometers, light sources, etc.), overcoming the limitation that traditional coupled waveguides are difficult to integrate, and is suitable for compact on-chip photonic systems.

[0009] Furthermore, the first mode converter and the second mode converter respectively convert the fundamental mode in the first curved tapered waveguide and the second curved tapered waveguide into a specific coupling mode in the first coupling waveguide, and the specific coupling mode has a specific dispersion value for dispersion compensation. Through the above-mentioned first mode converter and second mode converter, a specific coupling mode can be excited to achieve a dispersion compensation function. The length of the first coupling waveguide is determined by the specific application.

[0010] Furthermore, the first mode converter and the second mode converter each include a first multimode waveguide and a third curved tapered waveguide, and the first multimode waveguide and the third curved tapered waveguide are arranged at intervals to achieve mode conversion from a fundamental mode to a specific coupling mode in the first coupling waveguide.

[0011] Furthermore, the first coupled waveguide includes a second single-mode waveguide and a second multimode waveguide, the second single-mode waveguide and the second multimode waveguide are spaced apart, two ends of the second multimode waveguide are respectively connected to two first multimode waveguide output ends, and two ends of the second single-mode waveguide are respectively connected to two third curved tapered waveguide output ends.

[0012] Furthermore, the fundamental mode in the second single-mode waveguide is coupled with the high-order mode in the second multimode waveguide to form a specific coupling mode, and the specific coupling mode includes a symmetric mode and an antisymmetric mode, both of which have opposite dispersion compensation values; the first coupling waveguide operates in a weak phase matching region. The first coupling waveguide can be used for coupling between the fundamental mode (such as TE0) and a specific high-order mode (such as TE1, TE2, TE3...) to achieve dispersion compensation; the first mode converter and the second mode converter can be designed to excite the symmetric mode or antisymmetric mode in the first coupling waveguide, specifically by adjusting the width change of the third tapered single-mode waveguide in the mode converter. The working wavelength of the first coupling waveguide is designed in a weak coupling region adjacent to the phase matching region to reduce the power exchange between the single-mode waveguide and the multimode waveguide, so as to avoid the jump between the coupling modes and reduce the power coupling of the single-mode waveguide input to the multimode waveguide.

[0013] Further, the width of the first multimode waveguide is greater than the width of the third curved tapered waveguide, the width of the input end of the third curved tapered waveguide is less than the width of the output end of the third curved tapered waveguide; the width of the second single-mode waveguide is equal to the width of the output end of the third curved tapered waveguide.

[0014] Furthermore, a width value of the second multimode waveguide is equal to a width value of the first multimode waveguide; and a width value of the second multimode waveguide is greater than a width value of the second single-mode waveguide.

[0015] Further, a spacing value between the first multimode waveguide and the third curved tapered waveguide is L1, a spacing value between the second single-mode waveguide and the second multimode waveguide is L2, and L1 is equal to L2.

[0016] Furthermore, by adjusting the size of L1 and L2, the size of the dispersion compensation value is adjusted. The dispersion compensation value can be flexibly tuned by adjusting the waveguide spacing of the first coupled waveguide, the waveguide spacing of the first mode converter, and the second mode converter during processing; the length of the first coupled waveguide is selected according to the specific dispersion compensation application.

[0017] Furthermore, the first coupling waveguide is a racetrack structure.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The dispersion compensation annular reflector of the present invention has efficient dispersion compensation capability, low requirements on processing technology, strong manufacturing feasibility and mass production potential; the coupled waveguide structure design is universal and can be adapted to a variety of material platforms, expanding the scope of application in different on-chip photonic integrated systems; the device provided by the present invention supports on-chip integration with other photonic devices, has good integration, overcomes the limitation that traditional coupled waveguides are difficult to integrate, and is suitable for compact on-chip photonic systems. The device provided by the present invention also has flexible tuning capabilities. By adjusting the spacing or operating wavelength of the coupled waveguides, the dispersion compensation intensity can be flexibly adjusted to meet different application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of a dispersion compensating annular reflector;

[0021] Figure 2 It is a structural schematic diagram of a mode converter in a dispersion compensating annular reflector and a mode simulation analysis diagram thereof;

[0022] Figure 3 A simulation diagram of antisymmetric mode transmission of a coupled waveguide in a dispersion-compensating ring reflector;

[0023] Figure 4 A simulation data diagram of group velocity dispersion of a coupled waveguide in a dispersion-compensating annular reflector;

[0024] Figure 5 The present invention is a schematic flow chart of the steps of a method for preparing a dispersion compensating annular reflector.

[0025] In the accompanying drawings: 1. first 1×2 multimode interferometer; 2. first curved tapered waveguide; 3. second curved tapered waveguide; 4. first mode converter; 5. second mode converter; 6. first coupled waveguide; 7. first single-mode waveguide; 8. first multimode waveguide; 9. third curved tapered waveguide; 10. second multimode waveguide; 11. second single-mode waveguide. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with specific implementation methods. The accompanying drawings are only used for exemplary descriptions and are only schematic diagrams, not actual drawings, and cannot be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0027] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0028] Embodiment 1

[0029] This embodiment is a first embodiment of the structure of a dispersion compensation annular reflector. Figure 1 As shown, it includes a sapphire substrate, a silicon waveguide core layer arranged on the substrate, and a first 1×2 multimode interferometer 1, a first curved tapered waveguide 2, a second curved tapered waveguide 3, a first mode converter 4, a second mode converter 5 and a first coupling waveguide 6 arranged on the silicon waveguide core layer; the first end and the second end of the waveguide section first 1×2 multimode interferometer 1 are respectively provided with one port and two ports, the port at the first end is connected to the incident and output waveguide sections through the first single-mode waveguide 7, and the incident and output waveguide sections of the waveguide section are the same section; the two ports at the second end are respectively connected to the input ends of the waveguide section first mode converter 4 and the waveguide section second mode converter 5 through the waveguide section first curved tapered waveguide 2 and the waveguide section second curved tapered waveguide 3, and the output ends of the waveguide section first mode converter 4 and the waveguide section second mode converter 5 are connected through the waveguide section first coupling waveguide 6.

[0030] In this embodiment, the first mode converter 4 of the waveguide cross section and the second mode converter 5 of the waveguide cross section both include a first multimode waveguide 8 and a third curved conical waveguide 9. The first multimode waveguide 8 of the waveguide cross section and the third curved conical waveguide 9 of the waveguide cross section are arranged at intervals to realize mode conversion from the fundamental mode to a specific coupling mode in the first coupling waveguide 6.

[0031] In this embodiment, the first coupling waveguide 6 is a racetrack structure; the waveguide cross-section of the first coupling waveguide 6 includes a second single-mode waveguide 11 and a second multimode waveguide 10, the waveguide cross-section of the second single-mode waveguide 11 is spaced apart from the waveguide cross-section of the second multimode waveguide 10, the two ends of the waveguide cross-section of the second multimode waveguide 10 are respectively connected to the output ends of the two first multimode waveguides 8, and the two ends of the waveguide cross-section of the second single-mode waveguide 11 are respectively connected to the output ends of the two third curved tapered waveguides 9.

[0032] In this embodiment, the waveguide cross-section first mode converter 4 and the waveguide cross-section second mode converter 5 respectively convert the fundamental mode in the first curved tapered waveguide 2 and the second curved tapered waveguide 3 into a specific coupling mode in the first coupling waveguide 6, and the waveguide cross-section specific coupling mode has a specific dispersion value for dispersion compensation. Through the above-mentioned first mode converter 4 and second mode converter 5, a specific coupling mode can be excited to achieve a dispersion compensation function. The length of the first coupling waveguide 6 is determined by the specific application.

[0033] The fundamental mode in the second single-mode waveguide 11 is coupled with the high-order mode in the second multimode waveguide 10 to form a specific coupling mode. The specific coupling mode of the waveguide section includes a symmetric mode and an antisymmetric mode, and the two have opposite dispersion compensation values. The first coupling waveguide 6 of the waveguide section works in the weak phase matching region. The first coupling waveguide 6 can be used for the fundamental mode (such as TE 0 ) and certain higher-order modes (such as TE 1 TE 2 TE 3 ...) to achieve dispersion compensation; the first mode converter 4 and the second mode converter 5 can be designed to excite the symmetric mode or antisymmetric mode in the first coupling waveguide 6, which is specifically achieved by adjusting the width change of the third tapered single-mode waveguide in the mode converter. The working wavelength of the first coupling waveguide 6 is designed in the weak coupling region adjacent to the phase matching region to reduce the power exchange between the single-mode waveguide and the multi-mode waveguide, so as to avoid the jump between the coupling modes and reduce the power coupling of the single-mode waveguide input to the multi-mode waveguide.

[0034] In this embodiment, the width value of the first multimode waveguide 8 of the waveguide cross section is greater than the width value of the third curved conical waveguide 9 of the waveguide cross section, and the width value of the input end of the third curved conical waveguide 9 of the waveguide cross section is less than the width value of the output end of the third curved conical waveguide 9; the width value of the second single-mode waveguide 11 of the waveguide cross section is equal to the width value of the output end of the third curved conical waveguide 9 of the waveguide cross section.

[0035] The width of the second multimode waveguide 10 of the waveguide cross section is equal to the width of the first multimode waveguide 8 of the waveguide cross section; the width of the second multimode waveguide 10 of the waveguide cross section is greater than the width of the second single-mode waveguide 11. The spacing between the first multimode waveguide 8 of the waveguide cross section and the third curved tapered waveguide 9 of the waveguide cross section is L1, and the spacing between the second single-mode waveguide 11 of the waveguide cross section and the second multimode waveguide 10 of the waveguide cross section is L2, and L1 is equal to L2.

[0036] In this embodiment, the dispersion compensation value of the waveguide cross section is adjusted by adjusting the size of L1 and L2. The dispersion compensation value can be flexibly tuned by adjusting the waveguide spacing of the first coupling waveguide 6, the waveguide spacing of the first mode converter 4, and the second mode converter 5 during processing; the spacing of the first coupling waveguide 6 has a direct impact on the dispersion compensation value: the dispersion compensation value is weakened when the spacing increases, and the dispersion compensation value is enhanced when the spacing decreases; the length of the first coupling waveguide 6 is selected according to the specific dispersion compensation application.

[0037] Working principle: The first 1×2 multimode interferometer 1 is used to realize 50:50 optical power splitting and combining; after the light input to the first 1×2 multimode interferometer 1 is evenly divided into two beams, the fundamental mode excitation is converted into a specific coupling mode through the first mode converter 4 of the waveguide section and the second mode converter 5 of the waveguide section respectively; after the two beams realize the dispersion compensation function in the first coupling waveguide 6 of the waveguide section, the specific coupling mode is converted back to the fundamental mode through the second mode converter 5 of the waveguide section and the first mode converter 4 of the waveguide section respectively, and the beams are combined in the first 1×2 multimode interferometer 1 of the waveguide section, and finally output from the first port of the first 1x2 multimode interferometer of the waveguide section to complete the dispersion compensation and optical feedback functions.

[0038] The dispersion-compensating annular reflector provided in this embodiment has high-efficiency dispersion compensation capability, low requirements for processing technology, strong manufacturing feasibility and mass production potential; the coupled waveguide structure design is universal and can be adapted to a variety of material platforms (such as silicon-based, silicon nitride-based, lithium niobate, etc.), expanding the application scope of the present invention in different on-chip photonic integrated systems; it has good integration with other devices, and the structural design of the present invention supports on-chip integration with other photonic devices (such as multi-mode interferometers, light sources, etc.), overcoming the limitation that traditional coupled waveguides are difficult to integrate, and is suitable for compact on-chip photonic systems. Flexible tuning capability By adjusting the spacing or operating wavelength of the coupled waveguides, the dispersion compensation intensity can be flexibly adjusted to meet different application requirements. The compact design has a small overall structural geometric size and occupies a low chip area, which is very suitable for the high requirements for spatial efficiency in on-chip photonic systems.

[0039] Embodiment 2

[0040] This embodiment is a second embodiment of the structure of a dispersion compensating annular reflector. This embodiment is similar to the first embodiment, except that this embodiment performs simulation based on the device structure provided in the first embodiment.

[0041] like Figure 2 As shown in a in FIG. 1 , it is a schematic diagram of the structure of two mode converters. The first mode converter 4 and the second mode converter 5 have the same structure, both of which include a first multimode waveguide 8 of a specific width and a third curved tapered waveguide 9, and the spacing between the two is kept fixed. By using the Lumerical FDE waveguide mode solver, a detailed numerical simulation of the mode evolution of the two mode converters under the change of the width of the third curved tapered waveguide 9 is carried out. Figure 2 As shown in b, the result of the effective refractive index of the mode converter changing with the width of the third curved conical waveguide 9 and the mode field distribution of the antisymmetric mode under a specific width. When the width of the third curved conical waveguide 9 at the input end of the mode converter is I, its mode field is mainly concentrated in the third curved conical waveguide 9, showing the fundamental mode. As the width of the third curved conical waveguide 9 gradually increases to II, the effective refractive index of the fundamental mode in the third curved conical waveguide 9 gradually approaches the effective refractive index of a certain high-order mode in the first multimode waveguide 8, and the two tend to phase match, thereby enhancing the coupling effect. At this time, the input fundamental mode gradually transforms into an antisymmetric mode, and a small part of the optical power is distributed to the first multimode waveguide 8. When the width of the third curved conical waveguide 9 is further increased to III, the mode converter enters the strong phase matching region, at which time the effective refractive index of the antisymmetric mode is closest to that of the symmetric mode, which easily leads to mode hopping. Under this width condition, mode coupling between coupling modes is inevitable. Therefore, in order to achieve efficient mode conversion, the width of the third curved tapered waveguide 9 in this embodiment is designed to gradually increase from I to II, so as to effectively excite the antisymmetric mode and avoid the mode hopping phenomenon between the coupled modes as much as possible. It should be noted that the length of the mode converter needs to be set to ensure adiabatic transmission of the mode.

[0042] It should be noted that the width of the second multimode waveguide 10 in the first coupling waveguide 6 is equal to the width of the first multimode waveguide 8 at the position II of the two mode converters, the width of the second single-mode waveguide 11 in the first coupling waveguide 6 is equal to the width of the third curved tapered waveguide 9 at the position II of the mode converter, and the waveguide spacing of the first coupling waveguide 6 is equal to the waveguide spacing of the mode converter. The numerical simulation results of the light field transmission in the first coupling waveguide 6 of the antisymmetric mode excited by the mode converter are shown in FIG. Figure 3 As shown, it can be seen that the antisymmetric mode maintains stable propagation in the coupled waveguide.

[0043] According to theoretical derivation (Applied Physics Letters, vol. 67, no. 15, pp. 2111-2113, 1995), the group velocity dispersion value of the coupling mode in the first coupling waveguide 6 is:

[0044]

[0045] Among them, D 0 is the fundamental mode group velocity dispersion in the second single-mode waveguide 11; κ is the waveguide coupling coefficient; v 1 v is the fundamental mode group velocity in the second single-mode waveguide 11; 2 is the high-order mode group velocity in the second multimode waveguide 10; ω is the angular frequency of the light wave; ω 0 represents the angular frequency of the phase-matched light wave; δω represents the coupled mode dispersion bandwidth. For the antisymmetric mode in the first coupled waveguide 6, its group velocity dispersion value is smaller than the fundamental mode dispersion value in the second single-mode waveguide 11, and anomalous dispersion is exhibited in the antisymmetric mode. The generation of optical frequency combs based on nonlinear effects usually requires anomalous dispersion conditions in the cavity. Therefore, in this embodiment, a dispersion-compensating circulator with anomalous dispersion is formed by exciting the antisymmetric mode.

[0046] like Figure 4 As shown in FIG. 1 , the numerical simulation results of the group velocity dispersion of the antisymmetric mode in the first coupled waveguide 6 are shown. Among them, the group velocity dispersion value (0-10000fs) of the fundamental mode in the second single-mode waveguide 11 is 2 / mm) is normal dispersion, while the antisymmetric mode in the first coupled waveguide 6 has obvious anomalous dispersion characteristics. As the waveguide spacing increases, the coupling effect between the waveguides gradually weakens, resulting in a decrease in the negative range of the anomalous dispersion value. By adjusting the spacing of the first coupled waveguide 6, the dispersion compensation capability can be flexibly tuned to meet the needs of different dispersion compensation applications.

[0047] Embodiment 3

[0048] This embodiment provides a method for preparing a dispersion compensating annular reflector, which is used to prepare the dispersion compensating annular reflector provided in Embodiment 1; Figure 5 As shown, the following steps are included:

[0049] S0. Clean the wafer surface;

[0050] S1. Spin coating electronic glue on the surface of silicon core layer;

[0051] S3. The pattern of the designed dispersion compensation annular reflector is transferred to the electronic glue by electron beam exposure, and the unnecessary part of the electronic glue is removed by development to obtain an electronic glue mask;

[0052] S4. transferring the mask structure to the silicon waveguide core layer by plasma etching;

[0053] S5. Remove electronic glue;

[0054] S6. Optionally, a silicon dioxide thin film is deposited as a cladding layer.

[0055] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0056] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A dispersion compensating annular reflector, characterized in that: The invention comprises a substrate, a silicon waveguide core layer arranged on the substrate, and a first 1×2 multimode interferometer (1), a first curved tapered waveguide (2), a second curved tapered waveguide (3), a first mode converter (4), a second mode converter (5) and a first coupling waveguide (6) arranged on the silicon waveguide core layer; the first end and the second end of the first 1×2 multimode interferometer (1) are respectively provided with one port and two ports, the port at the first end is connected to an incident waveguide section through a first single-mode waveguide (7), and the incident waveguide sections are the same section; the two ports at the second end are respectively connected to the input ends of the first mode converter (4) and the second mode converter (5) through the first curved tapered waveguide (2) and the second curved tapered waveguide (3), and the output ends of the first mode converter (4) and the second mode converter (5) are connected through the first coupling waveguide (6).

2. The dispersion compensating annular reflector according to claim 1, characterized in that: The first mode converter (4) and the second mode converter (5) respectively convert the fundamental mode in the first curved tapered waveguide (2) and the second curved tapered waveguide (3) into a specific coupling mode in the first coupling waveguide (6), wherein the specific coupling mode has a specific dispersion value for dispersion compensation.

3. The dispersion compensating annular reflector according to claim 2, characterized in that: The first mode converter (4) and the second mode converter (5) both comprise a first multimode waveguide (8) and a third curved tapered waveguide (9); the first multimode waveguide (8) and the third curved tapered waveguide (9) are arranged at intervals and are used to achieve mode conversion from a fundamental mode to a specific coupling mode in a first coupling waveguide (6).

4. The dispersion compensating annular reflector according to claim 3, characterized in that: The first coupling waveguide (6) comprises a second single-mode waveguide (11) and a second multimode waveguide (10); the second single-mode waveguide (11) and the second multimode waveguide (10) are arranged at intervals; two ends of the second multimode waveguide (10) are respectively connected to the output ends of two first multimode waveguides (8); and two ends of the second single-mode waveguide (11) are respectively connected to the output ends of two third curved tapered waveguides (9).

5. The dispersion compensating annular reflector according to claim 4, characterized in that: The fundamental mode in the second single-mode waveguide (11) is coupled with the high-order mode in the second multimode waveguide (10) to form a specific coupling mode, wherein the specific coupling mode includes a symmetric mode and an antisymmetric mode, and the two modes have opposite dispersion compensation values; the first coupling waveguide (6) operates in a weak phase matching region.

6. The dispersion compensating annular reflector according to claim 5, characterized in that: The width of the first multimode waveguide (8) is greater than the width of the third curved tapered waveguide (9), and the width of the input end of the third curved tapered waveguide (9) is less than the width of the output end of the third curved tapered waveguide (9).

7. The dispersion compensating annular reflector according to claim 5, characterized in that: The width of the second single-mode waveguide (11) is equal to the width of the output end of the third curved tapered waveguide (9); the width of the second multi-mode waveguide (10) is equal to the width of the first multi-mode waveguide (8); and the width of the second multi-mode waveguide (10) is greater than the width of the second single-mode waveguide (11).

8. The dispersion compensating annular reflector according to claim 5, characterized in that: The spacing value between the first multimode waveguide (8) and the third curved tapered waveguide (9) is L1, and the spacing value between the second single-mode waveguide (11) and the second multimode waveguide (10) is L2, and L1 is equal to L2.

9. The dispersion compensating annular reflector according to claim 8, characterized in that: By adjusting the sizes of L1 and L2, the size of the dispersion compensation value is adjusted.

10. The dispersion compensating annular reflector according to any one of claims 1 to 9, characterized in that: The first coupling waveguide (6) is a racetrack structure.

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