Tunable filter based on MEMS micromirror

Abstract

The invention discloses a tunable filter based on an MEMS micromirror, the filter comprises a first reflection element, a second reflection element and a coupling element, the first reflection element comprises the MEMS micromirror, the MEMS micromirror comprises a silicon-based layer, a mirror surface layer and a driving layer, the driving layer is integrated in the central area of the silicon-based layer, and the coupling element is integrated in the silicon-based layer. The mirror surface layer is integrated on the driving layer and is driven by the driving layer to move; the second reflecting element and the mirror surface layer are oppositely arranged to form an F-P cavity; and the coupling element is coupled with the mirror surface layer and is used for outputting an output signal of the mirror surface layer. The tunable filter is formed based on the MEMS micromirror, the performance bottleneck of a traditional filter is broken through, and an advanced optical architecture with both high-speed tuning and high-precision filtering is achieved.

Description

Technical Field

[0001] This invention relates to the field of tunable filter manufacturing technology, and particularly to a tunable filter based on MEMS micromirrors. Background Technology

[0002] Tunable filters are facing unprecedented technical challenges in high-speed, high-precision applications, while also ushering in revolutionary development opportunities. In cutting-edge fields such as optical coherence tomography (OCT), coherent optical communication, lidar, and quantum optics, high-speed tunable filters are becoming core devices driving technological progress. However, traditional filters are limited by millisecond-level response speeds and nonlinear tuning characteristics, severely restricting real-time imaging quality and resolution. With the development and maturation of fiber optic grating sensing technology, fiber cavity tunable filters have shown significant advantages in tuning range and filtering accuracy, making them crucial in high-precision optical applications. Thanks to their all-fiber structure and precise Fabry-Pérot cavity (FP) design, these filters can achieve ultra-wide tuning ranges (e.g., C+L band coverage of 1530-1625nm), far exceeding the tuning capabilities of traditional liquid crystal tunable filters, making them particularly suitable for broadband OCT and multi-band optical communication applications. Meanwhile, its precision can easily reach over 1000, and when combined with fiber grating technology, it can achieve sub-picometer wavelength selection accuracy, providing an ideal solution for high-resolution spectral analysis and quantum optics experiments.

[0003] However, limited by mechanical tuning mechanisms (such as piezoelectric ceramic actuation or thermal tuning), their response speed is typically confined to the millisecond range. This inherent limitation severely restricts their application in scenarios requiring microsecond / nanosecond-level tuning speeds, such as real-time OCT imaging and high-speed optical switches. This "high precision but low speed" characteristic poses a significant challenge to fiber optic cavity filters in dynamic application scenarios. Summary of the Invention

[0004] This invention provides a tunable filter based on MEMS micromirrors, which reduces the space occupied by a tunable filter based on MEMS micromirrors and is easy to integrate.

[0005] A tunable filter based on MEMS micromirrors, wherein the filter includes a first reflective element, a second reflective element, and a coupling element, wherein...

[0006] The first reflective element includes a MEMS micromirror, which includes a silicon substrate, a mirror layer, and a driving layer. The driving layer is integrated in the central region of the silicon substrate, and the mirror layer is integrated on the driving layer and is driven to move by the driving layer.

[0007] The second reflective element is disposed opposite to the mirror layer to form an FP cavity;

[0008] The coupling element is coupled to the mirror layer to output the output signal of the mirror layer.

[0009] Furthermore, a first through-hole is formed vertically through the silicon substrate, and a second through-hole is formed vertically through the driving layer. The first through-hole and the second through-hole are connected.

[0010] The driving layer is integrated on one end face of the silicon substrate;

[0011] The mirror layer covers the first perforation from one side of one end face of the silicon substrate.

[0012] Furthermore, a coating layer is deposited on one end face or the other end face of the mirror layer, wherein one end face of the mirror layer is disposed away from the first perforation, and the other end face of the mirror layer is disposed close to the perforation.

[0013] Furthermore, when one end face of the mirror layer is coated with a film layer, one end of the coupling element is inserted into the second through hole, and one end face of the coupling element is disposed away from the film layer, while one end face of the second reflective element is disposed close to the film layer.

[0014] Furthermore, when the other end face of the mirror layer is coated with a film layer, the second reflective element is inserted into the second through hole, and one end face of the second reflective element is disposed close to the film layer, while one end face of the coupling element is disposed away from the film layer.

[0015] Furthermore, the filter also includes a sleeve, wherein,

[0016] The first reflective element, the second reflective element, and the coupling element are all housed within the sleeve;

[0017] The silicon substrate has a racket-shaped structure. The electrical leads of the silicon substrate are led out from the surface of the racket-shaped part of the silicon substrate. A notch is opened on one side of the sleeve. The ball handle-shaped part of the silicon substrate and the notch are locked together. The notch is used to lead out the electrical leads, which are connected to an external signal generator.

[0018] Furthermore, the sleeve is made of glass, metal, or zirconium oxide ceramic material.

[0019] Furthermore, one end face of the coating layer and the second reflective element is configured as a flat-concave surface, that is, one end face of the coating layer and the second reflective element are respectively a flat surface and a concave surface.

[0020] Furthermore, the distance between the coupling element and the first reflective element is controlled to be within 1000um, and the distance of the transmitted light propagating through the mirror layer to the coupling element is less than 1000um.

[0021] Furthermore, both the second reflective element and the coupling element are optical fibers.

[0022] This invention discloses a tunable filter based on MEMS micromirrors. This tunable filter, formed using MEMS micromirrors, overcomes the performance bottlenecks of traditional filters, achieving an advanced optical architecture that combines high-speed tuning with high-precision filtering. This architecture enables rapid and precise control of the fiber cavity length, preserving the high spectral resolution characteristics of the fiber optic system while achieving microsecond-level dynamic response of MEMS technology. Through the integration of optomechanically optimized hollowed-out MEMS mirrors with the fiber optic FP cavity, it provides an ideal solution for applications such as real-time OCT imaging and dynamic optical communication. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of a MEMS micromirror according to an embodiment of the present invention;

[0025] Figure 2 This is a partial cross-sectional structural diagram of a tunable filter when one end face of the mirror layer is coated with a film layer, according to an embodiment of the present invention.

[0026] Figure 3 This is a partial cross-sectional structural diagram of a tunable filter when the other end face of the mirror layer is coated with a film layer, according to an embodiment of the present invention.

[0027] Figure 4 This is a three-dimensional structural schematic diagram of a tunable filter based on a MEMS micromirror according to an embodiment of the present invention.

[0028] Figure 5 As an embodiment of the present invention Figure 2 The partial cross-sectional structure of the tunable filter is shown as an example, illustrating the light field formed after transmitted light passes through the mirror layer.

[0029] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and the accompanying drawings. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that all directional indications in the embodiments of the present invention, such as up, down, left, right, front, back, etc., are only used to explain the relative positional relationship and movement of the components in a specific posture as shown in the attached figure. If the specific posture changes, the directional indication will also change accordingly.

[0032] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0033] In recent years, MEMS micromirror technology has achieved revolutionary breakthroughs, making significant progress in MHz-level ultra-high-speed tuning. Based on the latest research results (Nature Photonics, 2022; IEEE JMEMS, 2023) and core patented technology (US20230152671A1), a novel resonant structure driven by bistable electrostatic combs has been used to raise the mechanical resonant frequency to the 5-10 MHz range. Secondly, heterogeneous integrated micromirrors based on aluminum nitride piezoelectric thin films have achieved excellent performance with a 20° optical deflection angle and a 2.3 MHz resonant frequency. Furthermore, a hollow mirror structure designed through optomechanical topology optimization (Optica, 2024) maintains a mirror flatness of 10 μm while improving the quality factor to over 5000. These breakthroughs make it possible for MEMS micromirrors to achieve sub-microsecond wavelength switching in applications such as lidar (US11415661B2 patent) and OCT.

[0034] This invention utilizes a tunable filter based on MEMS micromirrors to overcome the performance bottlenecks of traditional filters, achieving an advanced optical system that combines high-speed tuning and high-precision filtering. Fiber optic cavities, with their ultra-wide tuning range (C+L band) and ultra-high precision (F>1000), can provide sub-picometer wavelength selection accuracy; while MEMS micromirrors, with their MHz-level ultra-high-speed tuning capability, can significantly improve the system response speed. This hybrid architecture enables rapid and precise control of the fiber cavity length, preserving the high spectral resolution characteristics of fiber optic systems while achieving microsecond-level dynamic response of MEMS technology. Through the integration of optomechanically optimized hollowed-out MEMS mirrors with special fiber optic FP cavities, it provides an ideal solution for applications such as real-time OCT imaging and dynamic optical communication. A detailed explanation follows.

[0035] In this invention, the proposed FP cavity is a Fabry-Perot resonator, or simply a Fabry-Perot cavity. Its simplest form consists of a pair of parallel mirrors. The injected light field is reflected multiple times between the mirrors, achieving the effects of increased light field intensity and wavelength selectivity. Fabry-Perot cavities are widely used in various lasers, communications, sensing, and high-resolution spectrometers. A resonator in which light does not leak out after multiple round trips within the cavity is called a stable cavity. The stability condition of a Fabry-Perot cavity under the paraxial approximation is as follows:

[0036]

[0037] Where R1 and R2 are the radii of curvature of the mirrors, and L is the distance between the two mirrors, referred to as the cavity length. When the frequency of the input light field meets certain conditions, multiple reflections will interfere with each other, resulting in a significant enhancement of the circulating field within the cavity. For a given cavity length L, the resonant frequency v0... q for:

[0038]

[0039] Where c is the speed of light, when light satisfying the resonance frequency is input into the cavity, the cavity resonance power spectrum exhibits an infinite number of equally spaced longitudinal modes. The frequency difference v between two adjacent longitudinal modes is... q+1 -v q This is called the free spectral range v FSR for:

[0040]

[0041] The fiber cavity tunable filter utilizes the principle of cavity length variation for spectral modulation. The scanning speed of the tunable filter depends on the rate of cavity length variation. Current fiber cavity tunable filters integrate the fiber cavity onto piezoelectric ceramics to scan the cavity length, with resonant frequencies typically below 50kHz. This invention innovatively employs a MEMS micromirror and a concave fiber surface to form a Fabry-Perot cavity, using the high-speed vibration of the MEMS micromirror to tune the cavity length, thus achieving a high-speed tunable filter.

[0042] Based on the aforementioned improvements, this embodiment of the invention provides a tunable filter based on a MEMS micromirror. The filter includes a first reflective element 1, a second reflective element 2, and a coupling element 3. The first reflective element 1 includes a MEMS micromirror, which includes a silicon substrate 11, a mirror layer 12, and a driving layer 13. The driving layer 13 is integrated in the central region of the silicon substrate 11, and the mirror layer 12 is integrated on the driving layer 13 and driven to vibrate by the driving layer 13. The second reflective element 2 is disposed opposite to the mirror layer 12 to form an FP cavity. The coupling element 3 is coupled to the mirror layer 12 and is used to output the output signal of the mirror layer 12.

[0043] The present invention will now be described in detail.

[0044] This invention is a tunable filter based on MEMS micromirrors; that is, the core component of the tunable filter of this invention is a MEMS micromirror. In some embodiments of this invention, such as... Figure 1 The diagram shows a cross-sectional view of a MEMS micromirror, which adopts a sandwich-like layered structure, including but not limited to a silicon base layer 11, a mirror layer 12, and a driving layer 13.

[0045] The driving layer 13 is precisely integrated into the central region of the silicon substrate 11 and integrally formed, that is, the driving layer 13 is integrated into the central region of one end face of the silicon substrate 11 and integrally formed. The mirror layer 12 is integrated on the driving layer 13 and is driven to move by the driving layer 13. In addition, in order to achieve efficient transmission light coupling, the central regions of both the driving layer 13 and the silicon substrate 11 are set to be hollowed out, that is, the silicon substrate 11 has a first through hole 111 that runs longitudinally through the silicon substrate 11, and the driving layer 13 has a second through hole 112 that runs longitudinally through the driving layer 13. The first through hole 111 and the second through hole 112 are connected. In this embodiment, by setting the first through hole 111 and the second through hole 112, there is no optical absorbing material to block the transmission light field, thereby reducing the propagation loss of the transmission light field.

[0046] In some embodiments of the present invention, such as Figure 1As shown, the mirror layer 12 covers the first perforation 111 from one side of the end face of the silicon substrate 11. Additionally, in this embodiment, for example, the diameter of the first perforation 111 is smaller than the diameter of the second perforation 112, and the second perforation 112 can be a T-shaped perforation, with one end of the second perforation 112 having a smaller lateral width than the other end.

[0047] In some embodiments of the present invention, the driving layer 13 drives the mirror layer 12 to support multiple driving modes, including electrostatic driving, electromagnetic driving, and piezoelectric driving, which can precisely control the mirror layer 12 to generate a thickness direction displacement greater than λ / 2 (where λ is the operating wavelength). Furthermore, in this invention, the silicon substrate, mirror layer, and driving layer of a traditional MEMS micromirror are improved, while other electrical circuit components are not modified; therefore, other electrical circuit components will not be described in detail here.

[0048] In some embodiments of the present invention, the mirror layer 12 is made of low-loss materials such as optical-grade glass or quartz, and the preferred film layer is a multilayer TaO2 / SiO2 dielectric film, which can achieve high reflectivity and low absorption loss.

[0049] In some embodiments of the present invention, one end face of the mirror layer 12 is disposed away from the first perforation 111, and the other end face of the mirror layer 12 is disposed close to the perforation. One end face or the other end face of the mirror layer 12 is coated with a coating layer 121. The two cases are described in detail below:

[0050] A: When one end face of the mirror layer 12 is coated with a coating layer 121:

[0051] like Figure 2 As shown, one end of the coupling element 3 is inserted into the second through hole 112, and the end face of the coupling element 3 is set away from the coating layer 121. The end face of the second reflective element 2 is set close to the coating layer 121. At this time, an FP cavity is formed between the end face of the second reflective element 2 and the coating layer. The mirror layer can be driven to vibrate by the driving layer 13.

[0052] B: When one end face of the mirror layer 12 is coated with a coating layer 121:

[0053] like Figure 3 As shown, the second reflective element 2 is inserted into the second perforation 112, and one end face of the second reflective element 2 is positioned close to the coating layer 121, while one end face of the coupling element 3 is positioned away from the coating layer 121. At this time, an FP cavity is formed between the coating layers on one end face of the second reflective element 2, which can drive the mirror layer 12 to vibrate through the driving layer 13.

[0054] In some embodiments of the present invention Figure 2 and Figure 3 Both the second reflecting element 2 and the coupling element 3 mentioned above can be optical fibers or other types of reflective elements, such as lenses, etc., with optical fibers being preferred in this invention. Furthermore, in this embodiment, an FP cavity is formed between the MEMS micromirror and the surface of the second reflecting element. Its optical path length can be dynamically adjusted by the displacement of the MEMS micromirror, thereby achieving the scanning cavity length. The adjustment is achieved by driving the mirror layer through the driving layer 13 to displace it, ultimately achieving dynamic adjustment of the optical path length of the FP cavity.

[0055] In some embodiments of the present invention, when the second reflective element 2 is an optical fiber, single-mode optical fiber or polarization-maintaining optical fiber is preferably used. The MEMS micromirror is configured to achieve rapid displacement via electrostatic, electromagnetic, or piezoelectric actuation to modulate the optical path length of the resonant cavity at a scanning frequency greater than 50 kHz. The modulation methods include, but are not limited to, voltage tuning and temperature tuning. For example, changing the displacement of the MEMS micromirror by varying the voltage enables rapid scanning of the optical transmission peak. The rapid displacement change of the MEMS micromirror scans the cavity length to achieve rapid scanning of the optical transmission peak.

[0056] In some embodiments of the present invention, to ensure efficient transmission light coupling, the distance between the coupling element 3 and the first reflecting element 1 is controlled to be within 1000 μm, preferably within 50 μm, and the distance of transmission light propagating through the mirror layer 12 to the coupling element 3 is less than 1000 μm, preferably 100 μm. Additionally, as... Figure 4 The image shown is... Figure 2 The partial cross-sectional structure of the tunable filter is shown as an example. A schematic diagram of the light field formed after transmitted light passes through the mirror layer 12 is shown. The diameter of the mirror layer 12 is 10 μm. The mode field diameter of the optical fiber is generally around 10 μm. Therefore, when the propagation distance is less than 50 μm, the light field can be received by the optical fiber to the maximum extent, reducing coupling loss. When light is coupled from the mirror layer 12 into the optical fiber, its coupling efficiency depends on the degree of matching between the field distribution of the light source and the optical fiber mode. For a uniformly illuminated circular planar light source (mirror, i.e., the coating layer 121 in this invention), its maximum theoretical coupling efficiency L with the optical fiber (fundamental mode is Gaussian mode) is expressed by the following formula:

[0057]

[0058] Where ω1(z) is the beam radius of the light source at a distance z, ω2 is the mode field radius of the optical fiber (usually a constant), λ is the operating wavelength, and z is the gap distance. Preferably, when the distance between the mirror and the optical fiber is 50 μm, the loss is approximately 0.94 dB. The smaller the gap, the lower the loss. For example, when the gap is greater than 100 μm, the loss exceeds 3 dB.

[0059] In some embodiments of the present invention, to improve mode matching efficiency, one end face of the coating layer 121 and the second reflective element 2 is configured as a flat-concave surface, that is, one end face of the coating layer 121 and the second reflective element 2 is a flat surface and a concave surface, respectively. The flat-concave surface configuration can significantly improve coupling efficiency. The concave surface can be processed by precision mechanical grinding, chemical etching or laser ablation. When its radius of curvature is the same as the radius of curvature of the wavefront of the beam in the cavity, 100% mode matching efficiency can be achieved. This configuration effectively reduces insertion loss (i.e., the ratio of input optical power to transmission peak intensity) while ensuring the narrow linewidth and high precision characteristics of the filter.

[0060] In some embodiments of the present invention, such as Figure 5 What is shown is based on Figure 3 A three-dimensional structural diagram of the main internal components of the formed filter is provided, including components for fixing... Figure 3 Sleeve 4 of the structure ( Figure 4 In order to clearly see the structure of the internal components of the sleeve 4, the entire sleeve 4 is made of transparent material for easy understanding. The first reflective element 1, the second reflective element 2, and the coupling element 3 are all housed within the sleeve 4, which is made of glass, metal, or zirconium oxide ceramic. The silicon substrate 11 has a racket-shaped structure. Electrical leads of the silicon substrate 11 extend from the surface of the racket-shaped portion. A notch 41 is provided on one side of the sleeve 4, and the handle-shaped portion of the silicon substrate 11 is tightly fitted with the notch 41. The notch 41 is used to extend the electrical leads, which connect to an external signal generator. The following example illustrates the design using the first reflective element 1 as a MEMS micromirror, the second reflective element 2 as an input optical fiber, and the coupling element 3 as an output optical fiber.

[0061] The entire system is based on a sandwich-style coaxial structure design, precisely aligning the input fiber, MEMS micromirror, and output fiber using a precision ceramic sleeve. In terms of assembly, the coupling between the MEMS micromirror and the output fiber can employ reliable connection methods such as adhesive bonding or laser welding. Of particular note is the compact size of the MEMS micromirror, which allows it to be completely housed within the mounting space of the ceramic sleeve, ensuring seamless coupling between the input and output fiber assemblies within the sleeve. This design fully leverages the high-precision positioning characteristics of telecom-grade ceramic sleeves (typically achieving sub-micron level accuracy) while maintaining the system's cost advantage.

[0062] In the example, preferably, the MEMS micromirror is manufactured in the shape of a racket, with electrical wiring led out from the racket surface. To facilitate system integration, a slot is provided on one side of the ceramic sleeve, which fits snugly into the notch of the handle, used to position and fix the chip and prevent it from rotating. In addition, the notch is used to lead out the electrical leads of the MEMS micromirror, which can be directly connected to an external signal generator to achieve fast electrical control and optical response.

[0063] This example not only inherits the high precision and low cost advantages of standard telecommunications components, but also achieves efficient coupling and stable operation of optical elements through innovative mechanical design, providing a reliable solution for the miniaturization and commercial application of tunable filters.

[0064] Furthermore, in this example, fiber optic V-groove alignment technology can be employed, significantly improving system integration accuracy and assembly efficiency. Specifically, optical components such as the input fiber, MEMS micromirrors, and output fiber achieve sub-micron level automatic alignment through high-precision V-grooves. In practice, a V-groove substrate made of single-crystal silicon or quartz is selected, with the opening angle and depth of the V-groove precisely designed to perfectly match the outer diameter of standard communication optical fibers (such as SMF-28). The input and output fibers achieve self-alignment and positioning through the geometric constraints of the V-groove, with a positioning accuracy of ±0.5µm. The MEMS micromirrors are integrated into specific locations on the V-groove substrate using a flip-chip bonding process, with their reflective surfaces forming a precise perpendicular relationship with the fiber end faces, thus achieving sub-micron level automatic alignment.

[0065] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made under the concept of the present invention using the description and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A tunable filter based on MEMS micromirrors, characterized in that, The filter includes a first reflective element (1), a second reflective element (2), and a coupling element (3), wherein, The first reflective element (1) includes a MEMS micromirror, which includes a silicon substrate (11), a mirror layer (12) and a driving layer (13). The driving layer (13) is integrated in the central region of the silicon substrate (11), and the mirror layer (12) is integrated on the driving layer (13) and is driven by the driving layer (13) to move. The second reflective element (2) is disposed opposite to the mirror layer (12) to form an FP cavity; The coupling element (3) is coupled to the mirror layer (12) to output the output signal of the mirror layer (12).

2. The tunable filter based on MEMS micromirrors as described in claim 1, characterized in that, A first through-hole (111) is formed vertically through the silicon substrate (11), and a second through-hole (112) is formed vertically through the driving layer (13). The first through-hole (111) and the second through-hole (112) are connected. The driving layer (13) is integrated on one end face of the silicon substrate (11); The mirror layer (12) covers the first perforation (111) from one side of one end face of the silicon substrate (11).

3. A tunable filter based on MEMS micromirrors as described in claim 2, characterized in that, The mirror layer (12) has a coating layer (121) on one end face or the other end face, wherein one end face of the mirror layer (12) is disposed away from the first perforation (111), and the other end face of the mirror layer (12) is disposed close to the perforation.

4. A tunable filter based on MEMS micromirrors as described in claim 3, characterized in that, When one end face of the mirror layer (12) is coated with a coating layer (121), one end of the coupling element (3) is inserted into the second through hole (112), and one end face of the coupling element (3) is set away from the coating layer (121), while one end face of the second reflective element (2) is set close to the coating layer (121).

5. A tunable filter based on MEMS micromirrors as described in claim 3, characterized in that, When the other end face of the mirror layer (12) is coated with a coating layer (121), the second reflective element (2) is inserted into the second perforation (112), and one end face of the second reflective element (2) is positioned close to the coating layer (121), while one end face of the coupling element (3) is positioned away from the coating layer (121).

6. A tunable filter based on MEMS micromirrors as described in claim 4 or 5, characterized in that, The filter also includes a sleeve (4), wherein, The first reflective element (1), the second reflective element (2), and the coupling element (3) are all housed in the sleeve (4); The silicon substrate (11) has a racket-shaped structure. The electrical leads of the silicon substrate (11) are led out from the surface of the racket-shaped part of the silicon substrate (11). A notch (41) is opened on one side of the sleeve (4). The ball handle-shaped part of the silicon substrate (11) and the notch (41) are locked together. The notch (41) is used to lead out the electrical leads, which are connected to an external signal generator.

7. A tunable filter based on MEMS micromirrors as described in claim 5, characterized in that, The sleeve (4) is made of glass, metal or zirconium oxide ceramic material.

8. A tunable filter based on MEMS micromirrors as described in any one of claims 4 or 5, characterized in that, The coating layer (121) and the second reflective element (2) are configured with a flat-concave surface, that is, the coating layer (121) and the second reflective element (2) are respectively a flat surface and a concave surface.

9. A tunable filter based on MEMS micromirrors as described in claim 8, characterized in that, The distance between the coupling element (3) and the first reflective element (1) is controlled within 1000um, and the distance of the transmitted light propagating through the mirror layer (12) to the coupling element (3) is less than 1000um.

10. A tunable filter based on MEMS micromirrors as described in claim 1, characterized in that, The second reflective element (2) and coupling element (3) are both optical fibers.

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