A silicon-based integrated optical filter device with high extinction ratio

Abstract

The present invention discloses a silicon-based integrated optical filter device with a high extinction ratio. The silicon-based integrated optical filter device includes a first subwavelength grating reflector, a second subwavelength grating reflector, a first curved waveguide, a second curved waveguide, a first straight waveguide, a second straight waveguide, and a ring resonator located on a silicon substrate. The first subwavelength grating reflector is connected to the first curved waveguide, the second subwavelength grating reflector is connected to the second curved waveguide, the first curved waveguide is connected to the first straight waveguide, and the second curved waveguide is connected to the second straight waveguide. The first straight waveguide and the second straight waveguide are located on opposite sides of the ring resonator. The silicon-based integrated optical filter device provided by the present invention combines the ring resonator with two subwavelength grating reflectors to change the output spectrum of the ring resonator, thereby achieving filtering characteristics with a high extinction ratio. It also has the advantages of a compact structure, a simple manufacturing process, and low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of integrated optics, and in particular relates to a silicon-based integrated optical filter device with a high extinction ratio. Background Art

[0002] In this era of information explosion, society's demand for communication capacity is growing, but bandwidth resources in the communication band are extremely limited. This requires users to perform high-quality wavelength selection within the spectrum. Optical filters with low loss, narrow bandwidth, and high extinction ratios are particularly important in this regard. Furthermore, optical filters have important applications in active and passive components such as tunable lasers, wavelength division multiplexers / demultiplexers, and optical switching arrays. Compared to traditional fiber-based optical devices, integrated photonic devices are significantly smaller in size, enabling large-scale, high-density integration. Furthermore, integrated photonic devices fabricated on silicon-based platforms such as silicon and silicon oxide are virtually transparent in optical communication bands, offering low loss, low cost, simple fabrication processes, mature technology, and ease of scalability and industrialization.

[0003] Currently, most silicon-based integrated optical filter devices utilize microring resonators or on-chip stimulated Brillouin scattering (SBS). Implementation of SBS often requires high-power pump light injection to stimulate the Brillouin scattering effect, and complex device structures, such as photonic crystal structures and suspended waveguides, are required to achieve high Brillouin gain coefficients. These complex structures often require cumbersome fabrication processes, hindering scalability and industrialization. Silicon-based integrated optical filter devices based on microring resonators have attracted widespread attention in recent years due to their simple structure, ease of design, compact size, and facile fabrication. One of the key factors affecting the filtering characteristics of microring resonators is the optical loss within the resonator, which is significantly affected by the resonator's bending radius and the waveguide sidewall roughness. However, the structure of a single microring resonator is too simple and inflexible, and its filtering spectrum is easily limited by intracavity transmission and bending losses, as well as the sidewall roughness introduced by the fabrication process, making it difficult to achieve high extinction ratio filtering characteristics. Summary of the Invention

[0004] In order to overcome the defects of the prior art, the purpose of the present invention is to provide a silicon-based integrated optical filter device with a high extinction ratio. The present invention combines two sub-wavelength grating reflectors with a micro-ring resonator to further improve the extinction ratio of the silicon-based integrated optical filter device.

[0005] To achieve the above object, the present invention provides a silicon-based integrated optical filter device with a high extinction ratio, comprising a first sub-wavelength grating reflector, a second sub-wavelength grating reflector, a first curved waveguide, a second curved waveguide, a first straight waveguide, a second straight waveguide, a ring resonator, and a silicon-based substrate;

[0006] The first sub-wavelength grating reflector is connected to the first curved waveguide, and the second sub-wavelength grating reflector is connected to the second curved waveguide;

[0007] The first curved waveguide is connected to the first straight waveguide, and the second curved waveguide is connected to the second straight waveguide;

[0008] The first straight waveguide and the second straight waveguide are respectively located on opposite sides of the ring resonator, and the first straight waveguide and the second straight waveguide are both coupled to the ring resonator;

[0009] The first sub-wavelength grating reflector, the second sub-wavelength grating reflector, the first curved waveguide, the second curved waveguide, the first straight waveguide, the second straight waveguide, and the ring resonant cavity are all placed on the silicon-based substrate.

[0010] Furthermore, the first sub-wavelength grating reflector and the second sub-wavelength grating reflector are both sub-wavelength grating structures having periodic air-grating teeth.

[0011] Furthermore, the air teeth and grating teeth are rectangular waveguides that are periodically arranged alternately, and their width in one grating period is 0.1 micron to 1 micron, and their length is 0.1 micron to 1 micron.

[0012] Furthermore, the width ratio of the air teeth to the grating teeth in one grating period is 0-1, the length ratio is 0-1, and the number of grating periods is 1-5000.

[0013] Furthermore, the first curved waveguide and the second curved waveguide are quarter-circle ring structures with equal radius.

[0014] Furthermore, the annular resonant cavity is a combination of one or more closed annular structures, and the closed annular structure is in the shape of a circular ring or a racetrack ring.

[0015] Furthermore, the annular resonant cavity is two horizontally distributed circular rings with equal radius that are coupled to each other, two vertically distributed circular rings with equal radius that are not coupled to each other, a racetrack-shaped ring, or three mutually coupled circular rings with equal radius.

[0016] Furthermore, the widths of the cross sections of the first curved waveguide, the second curved waveguide, the first straight waveguide, the second straight waveguide, and the ring resonant cavity are all equal, and are all between 0.1 micrometer and 1 micrometer.

[0017] Furthermore, the cross-sectional heights of the first subwavelength grating reflector, the second subwavelength grating reflector, the first curved waveguide, the second curved waveguide, the first straight waveguide, the second straight waveguide, and the ring resonator are all equal, and are all 0.1 micrometer to 1 micrometer.

[0018] Furthermore, the ring resonator and the first straight waveguide, the ring resonator, and the second straight waveguide are all laterally coupled; the minimum spacing between the ring resonator and the first straight waveguide and the minimum spacing between the ring resonator and the second straight waveguide are both 0.1 micron to 0.3 micron.

[0019] Compared with the prior art, the present invention has the following beneficial effects: the high reflectivity of the first sub-wavelength grating reflector and the second sub-wavelength grating reflector forms a Fabry-Perot resonant cavity between the two, and then the Fabry-Perot resonant cavity is combined with the ring resonant cavity, so that the output spectrum of the ring resonant cavity changes, generating a new comb filter spectrum. The comb filter spectrum has very good periodicity and high extinction ratio filtering characteristics, and its free spectral range and filtering bandwidth can be changed by designing the structural parameters of the silicon-based integrated optical filter device to adapt to its application scenarios in different fields such as optical switches, optical exchanges, and optical communications. At the same time, the filtering characteristics of the silicon-based integrated optical filter device provided by the present invention will not be significantly affected by slight deviations in the device structure size caused by external factors such as the manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a top view of the silicon-based integrated optical filter device with a high extinction ratio provided by the present invention;

[0021] Figure 2 1 is a top view of a silicon-based integrated optical filter device with a high extinction ratio provided by Example 2 of the present invention;

[0022] Figure 3 1 is a top view of a silicon-based integrated optical filter device with a high extinction ratio provided by Example 3 of the present invention;

[0023] Figure 4 1 is a top view of a silicon-based integrated optical filter device with a high extinction ratio provided by Example 4 of the present invention;

[0024] Figure 5 1 is a top view of a silicon-based integrated optical filter device with a high extinction ratio provided by Example 5 of the present invention;

[0025] In the figure: 1-first sub-wavelength grating reflector, 2-second sub-wavelength grating reflector, 3-first curved waveguide, 4-second curved waveguide, 5-first straight waveguide, 6-second straight waveguide, 7-ring resonator, 8-silicon substrate. DETAILED DESCRIPTION

[0026] Exemplary embodiments are described in detail herein, with examples illustrated in the accompanying drawings. When the following description refers to the drawings, identical numerals in different drawings represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with this application.

[0027] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. As used in this application and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0028] It should be understood that although the terms first, second, third, etc. may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0029] The present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the present invention can be implemented in many different forms and should not be considered to be limited to the embodiments described herein. Rather, these embodiments are provided to make the present invention transparent and complete and to fully convey the scope of the present invention to those skilled in the art. In addition, the technical features involved in the various embodiments described below may be combined with each other as long as they do not conflict with each other.

[0030] The silicon-based integrated optical filter device with high extinction ratio provided by the embodiment of the present invention has a structure as follows: Figure 1 As shown, it includes a first sub-wavelength grating reflector 1, a second sub-wavelength grating reflector 2, a first curved waveguide 3, a second curved waveguide 4, a first straight waveguide 5, a second straight waveguide 6, a ring resonator 7 and a silicon-based substrate 8;

[0031] Among them, the first subwavelength grating reflector 1 is connected to the first curved waveguide 3; the second subwavelength grating reflector 2 is connected to the second curved waveguide 4; the first curved waveguide 3 is connected to the first straight waveguide 5; the second curved waveguide 4 is connected to the second straight waveguide 6; at the same time, the first straight waveguide 5 and the second straight waveguide 6 are respectively coupled to the ring resonator 7; and the first straight waveguide 5 and the second straight waveguide 6 are respectively located on opposite sides of the ring resonator 7; the first subwavelength grating reflector 1, the second subwavelength grating reflector 2, the first curved waveguide 3, the second curved waveguide 4, the first straight waveguide 5, the second straight waveguide 6, and the ring resonator 7 are all placed on a silicon-based substrate 8.

[0032] In the present invention, an input light wave first propagates through the first straight waveguide 5, passes through the first curved waveguide 3, and is reflected by the first subwavelength grating reflector 1. The reflected light wave is coupled into the second straight waveguide 6 through the coupling regions between the ring resonator 7, the first straight waveguide 5, and the second straight waveguide 6. It then passes through the second curved waveguide 4 and is reflected back by the second subwavelength grating reflector 2. It then passes through the coupling regions between the ring resonator 7, the second straight waveguide 6, and the first straight waveguide 5, and is coupled back into the first straight waveguide 5. It then passes through the first curved waveguide 3 and is reflected by the first subwavelength grating reflector 1. The input light wave is reflected back and forth between the first subwavelength grating reflector 1 and the second subwavelength grating reflector 2, forming a Fabry-Perot resonant cavity and generating a resonance effect. Simultaneously, the light wave also undergoes a resonance effect in the ring resonator 7. A portion of the Fabry-Perot resonant cavity formed above overlaps with the cavity of ring resonator 7. The cavity length of the Fabry-Perot resonant cavity is the sum of the distance from the first curved waveguide 3 to the coupling region between the first straight waveguide 5 and the ring resonator 7, the length of the first curved waveguide 3, the distance from the second curved waveguide 4 to the coupling region between the second straight waveguide 6 and the ring resonator 7, and the length of the second curved waveguide 4. The positions and directions of the first subwavelength grating reflector 1 and the second subwavelength grating reflector 2 can be changed according to the propagation direction of light in the ring resonator 7 to form a Fabry-Perot resonant cavity.

[0033] The integer multiple of the wavelength at which the Fabry-Perot resonant cavity resonates is equal to twice the product of the effective refractive index of the waveguide and the cavity length of the Fabry-Perot resonant cavity, while the integer multiple of the wavelength at which the ring resonant cavity 7 resonates is equal to the product of the effective refractive index of the waveguide and the cavity length of the ring resonant cavity 7. In the present invention, twice the cavity length of the Fabry-Perot resonant cavity is an integer multiple of the cavity length of the ring resonant cavity 7. In this way, the Fabry-Perot resonant cavity and the ring resonant cavity 7 have the same resonant wavelength. At these same resonant wavelengths, the resonance effect generated by the Fabry-Perot resonant cavity and the ring resonant cavity 7 is enhanced, thereby increasing the extinction ratio of the output spectrum and generating new periodic, high-extinction ratio comb filter spectrum lines. The free spectral range, filtering bandwidth and other filtering parameters of the comb filter spectrum can be changed by changing the grating period width and number of the first sub-wavelength grating reflector 1, the grating period width and number of the second sub-wavelength grating reflector 2, the radius of the first curved waveguide 3 and the second curved waveguide 4, the length of the first straight waveguide 5 and the second straight waveguide 6, the radius of the ring resonator 7 and other structural parameters. It has great flexibility and can adapt to applications in multiple fields such as optical switches, optical exchanges, and optical communications.

[0034] Preferably, the first sub-wavelength grating reflector 1 and the second sub-wavelength grating reflector 2 are both sub-wavelength grating structures having periodic air-grating teeth. The air teeth and grating teeth are rectangular waveguides arranged alternately and periodically, with a width of 0.1 μm to 1 μm and a length of 0.1 μm to 1 μm within one grating period. The width ratio of the air teeth to the grating teeth within one grating period is 0-1, and the length ratio is 0-1. The number of grating periods is 1 to 5000.

[0035] Preferably, the first curved waveguide 3 and the second curved waveguide 4 are quarter-circle ring structures with equal radius.

[0036] Preferably, the ring resonator 7 is a combination of one or more closed ring structures, and the closed ring structure is in the shape of a circular ring or a racetrack ring.

[0037] Preferably, the ring resonator 7 is two horizontally distributed, mutually coupled circular rings with equal radius.

[0038] Preferably, the ring resonator 7 is two vertically distributed circular rings with equal radius that are not coupled to each other.

[0039] Preferably, the ring resonator 7 is a racetrack ring.

[0040] Preferably, the ring resonator 7 is three mutually coupled circular rings with equal radius.

[0041] Preferably, the widths of the cross sections of the first curved waveguide 3 , the second curved waveguide 4 , the first straight waveguide 5 , the second straight waveguide 6 , and the ring resonant cavity 7 are all equal, and are all between 0.1 μm and 1 μm.

[0042] Preferably, the cross-sectional heights of the first subwavelength grating reflector 1 , the second subwavelength grating reflector 2 , the first curved waveguide 3 , the second curved waveguide 4 , the first straight waveguide 5 , the second straight waveguide 6 , and the ring resonator 7 are all equal, and are all 0.1 μm to 1 μm.

[0043] Preferably, the ring resonator 7 and the first straight waveguide 5 , and the ring resonator 7 and the second straight waveguide 6 are both laterally coupled.

[0044] Preferably, the minimum distance between the ring resonator 7 and the first straight waveguide 5 and the minimum distance between the ring resonator 7 and the second straight waveguide 6 are both 0.1 micrometer to 0.3 micrometer.

[0045] Moreover, those skilled in the art will readily understand that the silicon-based integrated filter device with a high extinction ratio of the present invention can be applied to multiple fields such as optical switches, optical switching, and optical communications.

[0046] The contents involved in the above embodiments are further explained below in conjunction with several preferred embodiments.

[0047] Example 1

[0048] In this embodiment, the ring resonator 7 is a single ring with a radius of 15 microns, and its cavity length is the circumference of the single ring, i.e., 94.25 microns. The first curved waveguide 3 and the second curved waveguide 4 both have a radius of 20 microns and a length of 31.42 microns. The distance from the first curved waveguide 3 to the coupling region between the first straight waveguide 5 and the ring resonator 7 is 86.39 microns, and the distance from the second curved waveguide 4 to the coupling region between the second straight waveguide 6 and the ring resonator 7 is also 86.39 microns. The first subwavelength grating reflector 1 and the second subwavelength grating reflector 2 have identical structural parameters, with a grating period of 500 nanometers. The width ratio of the air teeth to the grating teeth within one grating period is 1, and the length ratio is 1. The number of grating periods is 1024.

[0049] The Fabry-Perot resonant cavity formed between the first sub-wavelength grating reflector 1 and the second sub-wavelength grating reflector 2 has a cavity length of 235.62 microns. Twice the cavity length of the Fabry-Perot resonant cavity is five times the cavity length of the ring resonant cavity 7. This allows the Fabry-Perot resonant cavity and the ring resonant cavity 7 to have the same resonant wavelength. At these same resonant wavelengths, the resonance effects generated by the Fabry-Perot resonant cavity and the ring resonant cavity 7 reinforce each other, forming a filtering spectrum with a high extinction ratio.

[0050] Example 2

[0051] The top view of the silicon-based integrated optical filter device with high extinction ratio provided in Example 2 is as follows: Figure 2 As shown. In this embodiment, the ring resonator 7 is composed of two horizontally distributed, mutually coupled circular rings of equal radius, both with a radius of 7.5 microns. The radius of the first curved waveguide 3 and the second curved waveguide 4 are both 20 microns, and their lengths are both 31.42 microns. The distance from the first curved waveguide 3 to the coupling region between the first straight waveguide 5 and the ring resonator 7 is 86.39 microns, and the distance from the second curved waveguide 4 to the coupling region between the second straight waveguide 6 and the ring resonator 7 is also 86.39 microns. Compared with Example 1, the positions of the first sub-wavelength grating reflector 1 and the second sub-wavelength grating reflector 2 in this embodiment are adjusted according to the propagation direction of the input light in the ring resonator 7, so that the input light can be reflected back and forth between the first sub-wavelength grating reflector 1 and the second sub-wavelength grating reflector 2 to form a Fabry-Perot resonant cavity. The structural parameters of the first sub-wavelength grating reflector 1 and the second sub-wavelength grating reflector 2 in this embodiment are the same as those in Example 1.

[0052] In this embodiment, the Fabry-Perot cavity has a cavity length of 235.62 microns, which is twice the cavity length of the ring resonator 7, which is five times the cavity length of the ring resonator 7. Similar to Example 1, the Fabry-Perot cavity and the ring resonator 7 in this embodiment also have the same resonant wavelength and enhanced resonance effect, outputting a filtered spectrum with a high extinction ratio.

[0053] Example 3

[0054] The top view of the silicon-based integrated optical filter device with high extinction ratio provided in Example 3 is as follows: Figure 3 As shown. In this embodiment, the annular resonator 7 is composed of two vertically distributed circular rings of equal radius, both of which have a radius of 7.5 microns. The two vertically distributed circular rings do not couple with each other, and their left and right sides will couple with the first straight waveguide 5 and the second straight waveguide 6 respectively, and the distance between the center points of the two circular rings is 21 microns. The radius of the first curved waveguide 3 and the second curved waveguide 4 are both 20 microns, and their lengths are both 31.42 microns; the distance from the first curved waveguide 3 to the midpoint of the upper and lower circular ring coupling areas of the first straight waveguide 5 and the annular resonator 7 is 86.39 microns, and the distance from the second curved waveguide 4 to the midpoint of the upper and lower circular ring coupling areas of the second straight waveguide 6 and the annular resonator 7 is also 86.39 microns. The structural parameters of the first sub-wavelength grating reflector 1 and the second sub-wavelength grating reflector 2 in this embodiment are the same as those in Example 1.

[0055] In this embodiment, the length of the Fabry-Perot resonant cavity generated between the first sub-wavelength grating reflector 1 and the second sub-wavelength grating reflector 2 is 235.62 microns. The twice the length of the Fabry-Perot resonant cavity is five times the length of the ring resonant cavity 7. The resonance effect at their same resonant wavelength will be enhanced, forming a filtering spectrum line with a high extinction ratio.

[0056] Example 4

[0057] The top view of the silicon-based integrated optical filter device with high extinction ratio provided by Example 4 is as follows: Figure 4 As shown. In this embodiment, the ring resonator 7 is a racetrack-shaped ring, which is formed by connecting two upper and lower semicircles with a radius of 10 microns and two left and right straight waveguides with a length of 15.71 microns. The left and right straight waveguide parts of the ring resonator 7 are coupled with the first straight waveguide 5 and the second straight waveguide 6 respectively. The radius of the first curved waveguide 3 and the second curved waveguide 4 are both 20 microns, and their lengths are both 31.42 microns. The distance from the first curved waveguide 3 to the midpoint of the coupling area between the first straight waveguide 5 and the straight waveguide part on the left side of the ring resonator 7 is 86.39 microns, and the distance from the second curved waveguide 4 to the midpoint of the coupling area between the second straight waveguide 6 and the straight waveguide part on the right side of the ring resonator 7 is also 86.39 microns. The structural parameters of the first sub-wavelength grating reflector 1 and the second sub-wavelength grating reflector 2 in this embodiment are the same as those in Example 1.

[0058] In this embodiment, the Fabry-Perot cavity formed between the first subwavelength grating reflector 1 and the second subwavelength grating reflector 2 has a cavity length of 235.62 microns, while the cavity length of the ring resonator 7 is 94.25 microns. Twice the cavity length of the Fabry-Perot cavity is five times the cavity length of the ring resonator 7, thereby generating resonance enhancement at the same resonant wavelength, thereby forming a filter spectrum with a high extinction ratio.

[0059] Example 5

[0060] The top view of the silicon-based integrated optical filter device with high extinction ratio provided in this embodiment 5 is as follows: Figure 5As shown. In this embodiment, the ring resonator 7 is composed of three rings with equal radius on the left, middle and right sides, and their radius is 5 microns. Among them, the left ring is coupled with the first straight waveguide and the middle ring respectively, the middle ring is coupled with the left ring and the right ring respectively, and the right ring is coupled with the second straight waveguide and the middle ring respectively, and the left ring and the right ring are not coupled with each other. Compared with Example 2, the positions of the first sub-wavelength grating reflector 1 and the second sub-wavelength grating reflector 2 in this embodiment are changed according to the propagation direction of the input light in the ring resonator to ensure that the input light can be reflected back and forth between the first sub-wavelength grating reflector 1 and the second sub-wavelength grating reflector 2 to form a Fabry-Perot resonator. The structural parameters of the first sub-wavelength grating reflector 1 and the second sub-wavelength grating reflector 2 in this embodiment are the same as those in Example 1.

[0061] In this embodiment, the radius of the first curved waveguide 3 and the second curved waveguide 4 are both 20 microns, and their lengths are both 31.42 microns. The distance from the first curved waveguide 3 to the ring coupling region on the left side of the first straight waveguide 5 and the ring resonator 7 is 86.39 microns, and the distance from the second curved waveguide 4 to the ring coupling region on the right side of the second straight waveguide 6 and the ring resonator 7 is also 86.39 microns. The resulting Fabry-Perot resonator has a cavity length of 235.62 microns. The cavity length of the ring resonator 7 is the sum of the circumferences of the three rings, which is 94.25 microns. Similarly, in this embodiment, twice the cavity length of the Fabry-Perot resonator is five times the cavity length of the ring resonator 7, enabling the formation of a high extinction ratio filter spectrum.

[0062] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications derived therefrom remain within the scope of protection of the present invention.

[0063] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A silicon-based integrated optical filter device with a high extinction ratio, characterized in that: The silicon-based integrated optical filter device comprises a first sub-wavelength grating reflector (1), a second sub-wavelength grating reflector (2), a first curved waveguide (3), a second curved waveguide (4), a first straight waveguide (5), a second straight waveguide (6), a ring resonant cavity (7), and a silicon-based substrate (8); The first sub-wavelength grating reflector (1) is connected to the first curved waveguide (3), and the second sub-wavelength grating reflector (2) is connected to the second curved waveguide (4); The first curved waveguide (3) is connected to the first straight waveguide (5), and the second curved waveguide (4) is connected to the second straight waveguide (6); The first straight waveguide (5) and the second straight waveguide (6) are respectively located on opposite sides of the ring resonant cavity (7), and the first straight waveguide (5) and the second straight waveguide (6) are mutually coupled with the ring resonant cavity (7); The first sub-wavelength grating reflector (1), the second sub-wavelength grating reflector (2), the first curved waveguide (3), the second curved waveguide (4), the first straight waveguide (5), the second straight waveguide (6), and the ring resonant cavity (7) are all placed on the silicon-based substrate (8).

2. The silicon-based integrated optical filter device according to claim 1, wherein: The first sub-wavelength grating reflector (1) and the second sub-wavelength grating reflector (2) are both sub-wavelength grating structures having periodic air-grating teeth.

3. The silicon-based integrated optical filter device according to claim 2, wherein: The air teeth and the grating teeth are rectangular waveguides that are periodically arranged alternately. The width of the air teeth and the grating teeth in one grating period is 0.1 micron to 1 micron, and the length is 0.1 micron to 1 micron.

4. The silicon-based integrated optical filter device according to claim 2, wherein: The width ratio of the air teeth to the grating teeth in one grating period is 0-1, the length ratio is 0-1, and the number of grating periods is 1-5000.

5. The silicon-based integrated optical filter device according to claim 1, wherein: The first curved waveguide (3) and the second curved waveguide (4) are quarter-circular ring structures with equal radii.

6. The silicon-based integrated optical filter device according to claim 1, wherein: The annular resonant cavity (7) is a combination of one or more closed annular structures, and the closed annular structure is in the shape of a circular ring or a racetrack ring.

7. The silicon-based integrated optical filter device according to claim 6, wherein: The annular resonant cavity (7) comprises two horizontally distributed circular rings with equal radius that are coupled to each other, two vertically distributed circular rings with equal radius that are not coupled to each other, a racetrack-shaped ring, and three mutually coupled circular rings with equal radius.

8. The silicon-based integrated optical filter device according to claim 1, wherein: The widths of the cross sections of the first curved waveguide (3), the second curved waveguide (4), the first straight waveguide (5), the second straight waveguide (6), and the annular resonant cavity (7) are all equal, and are all between 0.1 micrometer and 1 micrometer.

9. The silicon-based integrated optical filter device according to claim 1, wherein: The cross-sections of the first sub-wavelength grating reflector (1), the second sub-wavelength grating reflector (2), the first curved waveguide (3), the second curved waveguide (4), the first straight waveguide (5), the second straight waveguide (6), and the ring resonant cavity (7) are all equal in height, ranging from 0.1 micrometer to 1 micrometer.

10. The silicon-based integrated optical filter device according to claim 1, wherein: The annular resonant cavity (7) and the first straight waveguide (5), the annular resonant cavity (7), and the second straight waveguide (6) are all laterally coupled; the minimum spacing between the annular resonant cavity (7) and the first straight waveguide (5), and the minimum spacing between the annular resonant cavity (7) and the second straight waveguide (6) are both 0.1 micrometer to 0.3 micrometer.

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