Micromirror chip, micromirror device, and optical device

Abstract

A micromirror chip (200), a micromirror device, and an optical device, relating to the technical field of optical communications. The micromirror chip (200) comprises a substrate (1), a micromirror (2), a rotating platform (3), a cantilever beam (4), a support post (5), and a counterweight (6); the rotating platform (3) is connected to the substrate (1) by means of the cantilever beam (4), the micromirror (2) is fixed above the rotating platform (3) by means of the support post (5), and the counterweight (6) is fixed below the rotating platform (3); the substrate (1) has a surface at a position opposite the counterweight (6) in an arrangement direction of the counterweight (6), the rotating platform (3), and the support post (5), and there is a gap between mutually-facing surfaces of the substrate (1) and the counterweight (6) in the arrangement direction. The structure improves micromirror (2) rotational accuracy, and also allows for good hermeticity in substrates (1) of MEMS micromirror chips (200).

Description

Micromirror chips, micromirror devices and optical equipment

[0001] This disclosure claims priority to Chinese Patent Application No. 202411497059.6, filed on October 24, 2024, entitled “Micromirror Chip, Micromirror Device and Optical Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of optical communication technology, and in particular to a micromirror chip, micromirror device, and optical equipment. Background Technology

[0003] Micromirror chips, such as micro-electro-mechanical systems (MEMS), are chip systems that achieve driving and sensing purposes through the interaction of electrical and mechanical structures. Optical MEMS chips (such as MEMS micromirror chips) are a very important type, achieving effects such as deflection, scanning, or modulation of light beams by moving reflective surfaces, gratings, waveguides, or other optical structures. For example, the structure of a MEMS micromirror chip mainly includes a substrate, a micromirror, and a rotating stage. The rotating stage is fixed to the substrate by a cantilever beam, and the micromirror is fixed to the surface of the rotating stage. When the external driving circuit drives the rotating stage to rotate, the micromirror rotates synchronously with the rotating stage to control the incident light.

[0004] As the size of micromirrors increases, or the rotation angle increases, or the number of micromirrors integrated on a MEMS micromirror chip increases, the area of ​​the MEMS micromirror chip will increase significantly. In order to reduce the area of ​​the MEMS micromirror chip and improve its space utilization, micromirrors are generally fixed to the surface of the rotary table by support columns, and the micromirrors are raised relative to the rotary table. In this way, the space under the micromirror can be used to arrange the driving structure. This three-dimensional stacking design prevents the area of ​​the MEMS micromirror chip from increasing significantly.

[0005] However, elevating the micromirror as described above weakens its vibration resistance, thus reducing the mechanical stability of the MEMS micromirror chip. For example, in practical applications, especially when the MEMS micromirror chip is subjected to external environmental impacts, a deviation may easily occur between the actual rotation angle of the micromirror and the controlled target angle, leading to a decrease in the stability of the MEMS micromirror chip. Summary of the Invention

[0006] This disclosure provides a micromirror chip, a micromirror device, and an optical device, which can improve the rotational accuracy of the micromirror and also enable the substrate of the micromirror chip to have good hermeticity.

[0007] In a first aspect, this disclosure provides a micromirror chip, such as a MEMS micromirror chip, comprising a substrate, a micromirror, a rotating stage, a cantilever beam, a support column, and a balance block;

[0008] The rotating stage is connected to the substrate via the cantilever beam, the micromirror is fixed above the rotating stage via the support column, and the balance block is fixed below the rotating stage.

[0009] The substrate has a surface in the arrangement direction of the support column, the rotary table and the balance block, and at a position opposite to the balance block, and there is a gap between the surfaces of the substrate and the balance block that face each other in the arrangement direction.

[0010] Among them, the balance block, the rotary table and the support column are generally arranged in a direction perpendicular to the rotary table. Therefore, the arrangement direction mentioned above can also be called the direction perpendicular to the rotary table.

[0011] In the scheme disclosed herein, a counterweight is arranged below the rotating stage of the MEMS micromirror chip, facing away from the micromirror, to ensure that the center of mass of the rotating body rotating around the rotation axis is near the rotation axis, thereby improving the vibration resistance of the micromirror. When the MEMS micromirror chip is subjected to impacts from the external environment, the micromirror is less prone to shaking, thus improving the accuracy and stability of the MEMS micromirror chip. Although a counterweight is arranged between the rotating stage and the substrate, the substrate still has a surface in the direction perpendicular to the rotating stage and opposite to the counterweight, which enables the MEMS micromirror chip substrate to have good hermeticity.

[0012] In one possible implementation, the balance blocks are fixed below the rotary table and along its axis of rotation. For example, the balance blocks may be arranged entirely along the axis of rotation below the rotary table, in which case the length of the rotary table along the axis of rotation is equal to the length of the balance blocks along the axis of rotation, or the length of the balance blocks is greater than the length of the rotary table. As another example, the balance blocks may be arranged partially along the axis of rotation below the rotary table, in which case the length of the rotary table along the axis of rotation is greater than the length of the balance blocks along the axis of rotation.

[0013] In the scheme shown in this disclosure, the center of mass of each part of the balance block along the axis of rotation is relatively close to the axis of rotation, which helps to reduce the moment of inertia of the balance block and thus weaken the influence of the balance block on the resonant frequency of the micromirror.

[0014] Moment of inertia is a physical quantity that describes the property of an object to resist changes in its rotational state when it is rotating. The closer the center of mass of the object is to the axis of rotation, the smaller the moment of inertia. Moment of inertia affects the resonant frequency of the object. For example, the larger the moment of inertia, the smaller the resonant frequency. For MEMS micromirror chips, the smaller the resonant frequency of the micromirror, the slower the response speed of the micromirror.

[0015] In addition, balance blocks are arranged along the rotation axis of the rotary table below it. This helps to increase the area of ​​the balance blocks, which is beneficial for balancing the micromirrors and improving their vibration resistance.

[0016] In one possible implementation, the rotary table has a first rotation axis and a second rotation axis, and the balance block is fixed below the rotary table along both the first and second rotation axes.

[0017] In the scheme disclosed herein, balance blocks are arranged on both rotation axes of the rotary table, which can reduce the degree of wobbling of the micromirror around the first rotation axis and also reduce the degree of wobbling of the micromirror around the second rotation axis.

[0018] In one possible implementation, the centerline of the balance block is parallel to the corresponding axis of rotation, and the plane containing the centerline of the balance block and the corresponding axis of rotation is parallel to the arrangement direction of the support column, the rotary table, and the balance block.

[0019] In the scheme disclosed herein, the centerline of the balance block is parallel to the corresponding axis of rotation, and in the arrangement direction of the support column, the rotary table, and the balance block, they are arranged one above the other, with their positions relatively distributed. For example, the balance block on the first axis of rotation has its centerline parallel to the first axis of rotation and is arranged vertically in the aforementioned direction; the balance block on the second axis of rotation has its centerline parallel to the second axis of rotation and is also arranged vertically in the aforementioned direction. This facilitates stable rotation of the rotary table around the first axis of rotation and also around the second axis of rotation, reducing the likelihood of uneven loading.

[0020] In one possible implementation, the micromirror includes a substrate and a reflective layer located on the surface of the substrate, wherein the density of the balance block is greater than or equal to twice the density of the substrate of the micromirror, and also greater than or equal to twice the density of the support column.

[0021] The substrates of the support pillars and micromirrors are generally formed by etching on the substrate. Therefore, the density of the substrates of the support pillars and micromirrors is the same as the density of the substrate. For example, they are both silicon-based materials (such as single-crystal silicon).

[0022] In the scheme disclosed herein, the density of the balance block is greater than that of the micromirror (e.g., the density of the balance block is more than twice that of single-crystal silicon). This allows the use of a relatively thin balance block, which pulls the center of mass of the rotating body rotating around the rotation axis onto the rotation axis, reducing the off-axis effect of the center of mass and making the micromirror less prone to wobbling around the rotation axis under external environmental impacts. Once the thickness of the balance block in the vertical direction perpendicular to the rotating stage is relatively thin, then there is no need to create cutouts in the substrate.

[0023] In one possible implementation, the thickness of the balancing block is less than half the thickness of the substrate, wherein the thickness of both the balancing block and the substrate is a dimension in the arrangement direction of the support column, the rotary table, and the balancing block.

[0024] In one possible implementation, the thickness of the balancing block is greater than or equal to 1 micrometer and less than or equal to 50 micrometers, wherein the thickness of the balancing block is the dimension in the direction of arrangement of the support column, the rotary table and the balancing block.

[0025] In one possible implementation, the center of mass of the balance block is close to the substrate relative to the rotary table.

[0026] In the scheme shown in this disclosure, since the micromirror and the support column located above the rotating stage are a whole, and their center of mass is close to the micromirror with a relatively large mass, a balance block with its center of mass closer to the substrate is needed below the rotating stage to pull the center of mass of the entire rotating body rotating around the rotation axis onto the rotation axis, so as to reduce the off-axis effect of the center of mass of the entire rotating body and improve the vibration resistance of the micromirror.

[0027] In one possible implementation, the micromirror chip further includes a transition block, which is arranged between the rotary table and the balance block, and the mass of the transition block is less than the mass of the balance block.

[0028] In the scheme shown in this disclosure, a transition block with a smaller mass is arranged between the substrate and the balance block, which enables the center of mass of the balance block to be close to the substrate.

[0029] In one possible implementation, the shape of the cross-section of the balance block in the direction perpendicular to the corresponding rotation axis is trapezoidal, and the top surface of the balance block is close to the rotary table, and the bottom surface is close to the substrate, wherein the area of ​​the top surface of the balance block is smaller than the area of ​​the bottom surface.

[0030] In the scheme shown in this disclosure, the cross-section of the balance block is trapezoidal, which also allows the center of mass of the balance block to be close to the substrate.

[0031] In one possible implementation, the balancing block has a multi-layer structure, with the stacked arrangement of the multiple layers of the balancing block parallel to the arrangement direction of the support column, the rotary table, and the balancing block itself, and the density of each layer increasing as it moves away from the rotary table.

[0032] In the scheme shown in this disclosure, the balance block has a multi-layer structure with different densities for each layer, and the density is greater closer to the substrate, which also allows the center of mass of the balance block to be closer to the substrate.

[0033] In one possible implementation, the balance block is made of metal.

[0034] In the scheme disclosed herein, the micromirrors and support pillars are generally supported by silicon-containing materials. The density of metal is greater than that of silicon-containing materials, for example, the density of metal is greater than that of single-crystal silicon. Therefore, the material of the balance block is metal, which enables the density of the balance block to be greater than or equal to twice the density of the micromirrors.

[0035] In one possible implementation, there are multiple micromirrors and multiple rotating stages, with each micromirror and rotating stage corresponding to the other, and the multiple micromirrors arranged in an array.

[0036] In a second aspect, a micromirror device is provided, the micromirror device comprising a substrate, a light-transmitting cover plate, and a micromirror chip as described in any of the first aspects;

[0037] The micromirror chip is located on the surface of the substrate, and the light-transmitting cover plate is fixed to the substrate or the substrate of the micromirror chip to form a receiving cavity, wherein the micromirror of the micromirror chip is located in the receiving cavity.

[0038] Thirdly, an optical device is provided, the optical device including an optical transmitter and the micromirror device described in the second aspect, wherein an optical signal emitted by the optical transmitter is incident on the micromirror of the micromirror device and reflected outward via the micromirror.

[0039] In one possible implementation, the optical device further includes an optical signal receiver for receiving optical signals, for example, for receiving optical signals emitted by another optical device. Attached Figure Description

[0040] Figure 1 is a schematic diagram of the structure of a MEMS micromirror chip provided by the prior art;

[0041] Figure 2 is a schematic diagram of the structure of a MEMS micromirror chip provided in an exemplary embodiment of this disclosure;

[0042] Figure 3 is a schematic diagram of the structure of a MEMS micromirror chip provided in an exemplary embodiment of this disclosure;

[0043] Figure 4 is a schematic diagram of the structure of a MEMS micromirror chip provided in an exemplary embodiment of this disclosure;

[0044] Figure 5 is a schematic diagram of the structure of a MEMS micromirror chip provided in an exemplary embodiment of this disclosure;

[0045] Figure 6 is a schematic diagram of the structure of a MEMS micromirror chip provided in an exemplary embodiment of this disclosure;

[0046] Figure 7 is a schematic diagram of the structure of a MEMS micromirror chip provided in an exemplary embodiment of this disclosure;

[0047] Figure 8 is a schematic diagram of the structure of a MEMS micromirror chip provided in an exemplary embodiment of this disclosure;

[0048] Figure 9 is a schematic diagram of the structure of a MEMS micromirror chip provided in an exemplary embodiment of this disclosure;

[0049] Figure 10 is a schematic diagram of the structure of a MEMS micromirror chip provided in an exemplary embodiment of this disclosure;

[0050] Figure 11 is a schematic diagram of the structure of a MEMS micromirror chip provided in an exemplary embodiment of this disclosure;

[0051] Figure 12 is a schematic diagram of the structure of a MEMS micromirror chip provided in an exemplary embodiment of the present disclosure;

[0052] Figure 13 is a schematic diagram of the structure of a MEMS micromirror chip provided in an exemplary embodiment of the present disclosure;

[0053] Figure 14 is a schematic diagram of the structure of a MEMS micromirror chip provided in an exemplary embodiment of this disclosure;

[0054] Figure 15 is a schematic diagram of the structure of a MEMS micromirror device provided in an exemplary embodiment of this disclosure.

[0055] Explanation of reference numerals in the attached figures: 1. Substrate; 11. Groove; 2. Micromirror; 3. Rotary stage; 4. Cantilever beam; 5. Support column; 6. Balance block; 7. Transition block; 8. Anchor point; 31. First rotating part; 32. Second rotating part; 33. Moving comb tooth; 34. Frame; 41. First cantilever beam; 42. Second cantilever beam; 61. First balance block; 62. Second balance block; 71. First transition block; 72. Second transition block; 81. First anchor point; 82. Second anchor point; 100. Substrate; 200. MEMS micromirror chip. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0057] This embodiment relates to a micromirror chip, specifically a micro-electro-mechanical system (MEMS) micromirror chip. A MEMS micromirror chip is a miniature optical component fabricated based on micromachining technology and semiconductor manufacturing technology, and is widely used in fields such as optical communication, projection imaging, and lidar.

[0058] Figure 1 shows a schematic diagram of the structure of a MEMS micromirror chip. Referring to Figure 1, the MEMS micromirror chip includes a substrate 1, which serves as the base of the MEMS micromirror chip and provides support. The substrate 1 is generally made of silicon-based materials, such as single-crystal silicon, silicon oxide, silicon nitride, silicon carbide, polycrystalline silicon, and doped silicon.

[0059] Referring to Figure 1, the MEMS micromirror chip also includes a micromirror 2. As the core component of the MEMS micromirror chip, the micromirror 2 is located above the substrate 1 and can rotate (or twist) relative to the substrate 1 to change the transmission path of light.

[0060] Referring to Figure 1, in order to enable the micromirror 2 to rotate, the MEMS micromirror chip also includes a rotating stage 3 and a cantilever beam 4. The rotating stage 3 is connected to the substrate 1 through the cantilever beam 4. For example, one side of the rotating stage 3 is connected to the substrate 1 through at least one cantilever beam 4, and the opposite side of the rotating stage 3 is also connected to the substrate 1 through at least one cantilever beam 4. Under the action of the cantilever beam 4, the rotating stage 3 is suspended above the substrate 1, and the micromirror 2 is fixed on the upper surface of the rotating stage 3 facing away from the substrate 1. Thus, as the rotating stage 3 rotates relative to the substrate 1, it drives the micromirror 2 to rotate.

[0061] Of course, in order to drive the rotating stage 3 to rotate, the MEMS micromirror chip will also include a driving mechanism, such as an electrostatically driven MEMS micromirror chip. The driving mechanism includes moving comb teeth and stationary comb teeth (refer to Figure 3). The moving comb teeth are disposed on the rotating stage 3. When there is a voltage difference between the moving comb teeth and the stationary comb teeth, an electrostatic force is generated between them. Under the action of the electrostatic force, the moving comb teeth can rotate relative to the stationary comb teeth, thereby driving the rotating stage 3 to rotate. It should be noted that the driving methods of the MEMS micromirror chip also include electromagnetic driving and piezoelectric driving, etc. This embodiment does not limit the driving method of the MEMS micromirror chip. For ease of explanation, the attached figure uses electrostatic driving as an example.

[0062] As the scanning range of the MEMS micromirror chip increases, and / or as the number of micromirrors increases, the size of the MEMS micromirror chip also increases significantly. In order to limit the significant increase in the size of the MEMS micromirror chip, the micromirror 2 is generally raised relative to the rotating stage 3, so that some structures of the driving mechanism can be arranged between the micromirror 2 and the substrate 1. Therefore, referring to Figure 1, the MEMS micromirror chip also includes a support column 5. The micromirror 2 is fixed above the rotating stage 3 by the support column 5, so that the micromirror 2 is raised relative to the substrate 1.

[0063] However, this brings another problem. Referring to Figure 1, the center of mass of the rotating body (the rotating body in Figure 1 is the part that rotates around the rotation axis L, including the rotating stage 3, the support column 5 and the micromirror 2) is deviated from the rotation axis L by a large margin. The off-axis effect of the center of mass of the rotating body is more obvious, which weakens the vibration resistance of the MEMS micromirror chip and reduces the accuracy of the micromirror rotation angle.

[0064] For example, applying a 100V voltage to a MEMS micromirror chip to control its rotation angle to 5 degrees may result in an actual rotation angle of 5.1 degrees under external impact. In scenarios where MEMS micromirror chips are used in optical devices (such as optical switches or optical cross-connectors), if there is a deviation between the actual rotation angle of the micromirror and the controlled target angle, the light reflected by the micromirror cannot accurately enter the next stage of optical components, leading to a decrease in the overall performance of the optical device containing the MEMS micromirror chip.

[0065] Therefore, in some solutions, a balance block 6 is arranged below the rotating stage 3, facing away from the micromirror 2. The balance block 6 is used to make the center of mass of the entire rotating body located near the axis of rotation L, thereby reducing the off-axis effect of the center of mass of the rotating body.

[0066] According to the principle of torque balance, in order for a rotating body (which includes a rotary table 3, a support column 5, a micromirror 2, and a balance block 6) to achieve mechanical equilibrium around the rotation axis L, it is necessary to satisfy m6×d6=m2×d2+m5×d5. When the rotating body achieves mechanical equilibrium, the center of mass of the rotating body is located on the rotation axis L.

[0067] In the above relationship, m6 is the mass of the balance block 6, d6 is the distance from the center of mass of the balance block 6 to the rotation axis L, m2 is the mass of the micromirror 2, d2 is the distance from the center of mass of the micromirror 2 to the rotation axis L, m5 is the mass of the support column 5, and d5 is the distance from the center of mass of the support column 5 to the rotation axis L.

[0068] It should be noted that in the above mechanical equilibrium formula, the center of mass of the rotary table 3 is located on the rotation axis L. If the center of mass of the rotary table 3 is above the rotation axis L, then m3 × d3 needs to be added to the right side of the equation. If the center of mass of the rotary table 3 is below the rotation axis L, then m3 × d3 needs to be added to the left side of the equation. Here, m3 represents the mass of the rotary table 3, and d3 represents the distance from the center of mass of the rotary table 3 to the rotation axis L.

[0069] Because the mass m6 of the balance block 6 is smaller than the mass m2 of the micromirror 2, d6 needs to be relatively large to satisfy the above balance relationship. With a larger d6, the balance block 6 will be thicker along the direction perpendicular to the rotating stage 3. As mentioned above, the balance block 6 is arranged below the rotating stage 3, and the substrate 1 is below the rotating stage 3. Therefore, to accommodate the thick balance block 6 between the rotating stage 3 and the substrate 1, a cutout is usually needed in the substrate 1 at the position corresponding to the balance block 6 to make room for its placement. Thus, the substrate 1 has a cutout penetrating the thickness of the substrate 1 directly below the balance block 6. Furthermore, because the balance block rotates with the rotating stage, the lateral dimension of the cutout is also relatively large, with the balance block 6 extending into the cutout in the substrate 1.

[0070] However, in the existing MEMS micromirror chips with balancing blocks, the substrate 1 has a relatively large cutout, which leads to a decrease in the airtightness of the MEMS micromirror chip.

[0071] Furthermore, due to the relatively large thickness of the balance block 6, its dimensions are longer in the direction perpendicular to the rotary table 3. This results in most parts of the balance block 6 being relatively far from the rotation axis L, leading to a larger moment of inertia (wherein, the moment of inertia is proportional to the fourth power of the distance from the center of mass to the rotation axis). Moment of inertia is a physical quantity describing the property of an object to resist changes in its rotational state. It affects the resonant frequency of an object; for example, a larger moment of inertia results in a lower resonant frequency. Therefore, the larger size of the balance block 6 in the direction perpendicular to the rotary table leads to a larger moment of inertia for the rotating body about the rotation axis, further reducing the resonant frequency of the rotating body, thereby lowering the resonant frequency of the micromirror. A lower resonant frequency results in a slower response speed of the micromirror.

[0072] Based on the above, this embodiment provides a MEMS micromirror chip. The balance block 6 used in the MEMS micromirror chip has a relatively small size in the direction perpendicular to the rotary table, that is, the thickness of the balance block 6 is relatively small, so that the substrate 1 does not need to be cut out. This ensures the airtightness of the MEMS micromirror chip on the one hand, and the rotational inertia of the balance block 6 is small, which has little impact on the resonant frequency of the micromirror 2 on the other hand.

[0073] The MEMS micromirror chip described in this embodiment will be introduced in detail below. The MEMS micromirror chip can be a single-axis MEMS micromirror chip or a dual-axis MEMS micromirror chip. For ease of introduction, the application of the balance block on a single-axis MEMS micromirror chip will be introduced first.

[0074] (a) MEMS micromirror chip with a single rotation axis.

[0075] Figures 2 to 4 show schematic diagrams of a MEMS micromirror chip with a single rotation axis. Figures 3 and 4 are three-dimensional schematic diagrams of the MEMS micromirror chip. Figure 3 shows a schematic diagram with micromirror 2 on top and rotating stage 3 on the bottom, and Figure 4 shows a schematic diagram with micromirror 2 on the bottom and rotating stage 3 on top. Figure 2 is the main view shown along the rotation axis L in Figure 3.

[0076] As shown in Figure 2, the surface of the substrate 1 has a groove 11, and the rotating platform 3 is located in the groove 11. As shown in Figure 3 and referring to Figure 2, the first side of the rotating platform 3 is connected to an anchor point 8 through at least one cantilever beam 4, and the second side of the rotating platform 3 is connected to another anchor point 8 through at least one cantilever beam 4. The first and second sides of the rotating platform 3 are positioned opposite each other, and the two anchor points 8 shown in Figure 3 are located on two opposite groove walls of the groove 11.

[0077] In order for the rotary table 3 to rotate stably, the rotation axis L of the rotary table 3 generally passes through the center line of the rotary table 3. Therefore, referring to Figure 3, the middle position of the first side of the rotary table 3 is connected to a cantilever beam 4, and the middle position of the second side of the rotary table 3 is connected to another cantilever beam 4. In this way, the center line of the rotary table 3 and the center lines of the two cantilever beams are collinear, and the straight line is the rotation axis L of the rotary table 3.

[0078] Referring again to Figure 3, the rotating platform 3 is platform-shaped. Both the third and fourth sides of the rotating platform 3 have movable comb teeth 33, enabling the rotating platform 3 to rotate in two directions, such as clockwise and counterclockwise. The third and fourth sides are positioned opposite each other, and the movable comb teeth 33 on the third and fourth sides of the rotating platform 3 are symmetrically distributed about the rotation axis L, so that the rotating platform 3 rotates at the same angle in both directions.

[0079] As shown in Figure 2, the micromirror 2 is fixed to the upper surface of the rotary table 3 by support columns 5. For example, if the micromirror 2 is fixed to the upper surface of the rotary table 3 by one support column 5, then the support column 5 is fixed at the center position of the upper surface of the rotary table 3, and the center position of the micromirror 2 is fixed to the support column 5. Alternatively, if the micromirror 2 is fixed to the upper surface of the rotary table 3 by multiple support columns 5, then the multiple support columns 5 are arranged sequentially along the length of the rotary table 3, the micromirror 2 is fixed on the multiple support columns 5, and the line containing the multiple support columns 5 is opposite to the diameter of the micromirror 2.

[0080] To improve the vibration resistance of the micromirror, as shown in Figure 2 and with reference to Figure 4, a balance block 6 is fixed to the bottom of the rotating stage 3, facing away from the micromirror 2. The balance block 6 is located between the rotating stage 3 and the substrate 1. Since movable comb teeth 33 are arranged on the third and fourth sides of the rotating stage 3, as shown in Figure 4, the balance block 6 is arranged between the movable comb teeth 33 on both sides of the rotating stage 3, facing away from the lower surface of the micromirror 2.

[0081] To ensure stable rotation of the rotary table 3, referring to Figure 4, the center line of the balance block 6 along its length is positioned relative to the rotation axis L of the rotary table 3 in a direction perpendicular to the rotary table 3. For example, the center line of the balance block 6 is parallel to the rotation axis and directly below it. This makes the rotary table 3 more stable when swinging left and right around the rotation axis.

[0082] Referring again to Figure 2, in this embodiment, the thickness of the balance block 6 in the direction perpendicular to the rotary table 3 is relatively small. This results in the substrate 1 having a surface at the position corresponding to the balance block 6 in the arrangement direction of the support column 5, the rotary table 3, and the balance block 6, which is also perpendicular to the rotary table 3. This makes the entire surface of the substrate continuous and without cutouts. Furthermore, there is a gap between the surfaces of the substrate 1 and the balance block 6 facing each other in the direction perpendicular to the rotary table, so as not to interfere with the rotational movement of the rotary table 3. For example, as shown in Figure 2, the bottom surface of the groove 11 of the substrate 1 is continuous and without cutouts, and there is a gap H between the bottom surface of the groove 11 and the lower surface of the balance block 6.

[0083] It should be noted that, in the direction perpendicular to the rotary table 3, the substrate 1 has a surface at the position corresponding to the balancing block 6. This surface could be an upper surface or a lower surface at the position corresponding to the balancing block 6. However, regardless of whether the substrate 1 has an upper or lower surface at the position corresponding to the balancing block 6, the substrate 1 is not cut out at that position. For ease of explanation, this text uses the example of the substrate 1 having an upper surface at the position corresponding to the balancing block 6.

[0084] In one example, there are several ways to achieve a small thickness of the balance block 6 in the direction perpendicular to the rotary table. One way is to use a material with a relatively high density for the balance block 6. For example, the density of the balance block 6 can be greater than or equal to twice the density of the micromirror 2, and also greater than or equal to twice the density of the support column 5.

[0085] In one example, the micromirror 2 generally includes a substrate and a reflective layer located on the surface of the substrate. The surface of the reflective layer serves as the reflective surface of the micromirror 2. The substrate and the reflective layer of the micromirror 2 are generally made of different materials. For example, the substrate and support pillars 5 of the micromirror 2 are generally formed on the substrate 1 by etching, so the materials of the substrate and support pillars 5 of the micromirror 2 are the same as the material of the substrate 1, which is generally a silicon-based material such as single-crystal silicon. The reflective layer of the micromirror 2 is generally made of a metal or a dielectric material, such as one or more of gold, aluminum, tantalum dioxide, and titanium dioxide, or silicon dioxide.

[0086] Therefore, the density of the balancing block 6 can be greater than or equal to twice the density of the micromirror 2, which can also be understood as the density of the balancing block 6 being greater than or equal to twice the density of the substrate of the micromirror 2. For example, if the substrate of the micromirror 2 is made of monocrystalline silicon, then the material of the balancing block 6 can be greater than or equal to twice the density of monocrystalline silicon.

[0087] In existing solutions that include a balance block, the balance block 6 is formed on the substrate 1 by etching. Therefore, the material of the balance block 6 is the same as that of the substrate 1. Thus, the materials of the balance block 6, the support pillar 5, and the substrate of the micromirror 2 are all the same. Therefore, existing solutions with balance blocks generally require a relatively thick balance block 6 to balance the support pillar 5 and the micromirror 2.

[0088] In one example, the material of the balance block 6 can be a metal, for example, the material of the balance block 6 can be at least one of gold, platinum and copper. Since the material of the balance block 6 is different from the material of the substrate 1, the balance block 6 is not formed under the rotary table 3 by semiconductor manufacturing process. The method of fixing the balance block 6 under the rotary table 3 can be one or a combination of evaporation, sputtering, electroplating, deposition, bonding and adhesive.

[0089] Another way to achieve a smaller thickness of the balance block 6 in the direction perpendicular to the rotary table is to increase the area of ​​the balance block 6. For example, as shown in Figure 4, balance blocks 6 are arranged along the rotation axis L below the rotary table 3. Since the balance block 6 cannot interfere with the movement of the moving comb teeth 33 on both sides of the rotary table 3, the balance blocks 6 are arranged in the area below the rotary table 3 where the moving comb teeth 33 are not located. Therefore, using a high-density, large-volume balance block 6 makes it easier to achieve a smaller thickness of the balance block 6.

[0090] In this way, a relatively thin balancing block 6 is used below the rotating stage 3 to balance the micromirror 2 and the support column 5 above the rotating stage 3. Because the balancing block 6 is relatively thin, the distance between the rotating stage 3 and the substrate 1 can accommodate the balancing block 6. Therefore, in the direction perpendicular to the rotating stage 3, the surface of the substrate 1 at the position corresponding to the balancing block 6 has continuity, and the substrate 1 has no cutouts, thereby ensuring the hermeticity of the MEMS micromirror chip.

[0091] Furthermore, since the resonant frequency of the micromirror 2 is affected by the moment of inertia of each object rotating around the axis of rotation, the balance block 6 has a smaller thickness and a smaller moment of inertia, and therefore has a weaker impact on the resonant frequency of the micromirror 2, such as not significantly reducing the resonant frequency of the micromirror 2.

[0092] As described above, the thickness of the balancing block 6 in the direction perpendicular to the rotary table is relatively small; for example, the thickness of the balancing block 6 in the direction perpendicular to the rotary table is less than half the thickness of the substrate 1. The thickness of the substrate 1 can be the thickness at its thickest point or the average thickness of the substrate 1. The thickness of the substrate 1 is generally greater than or equal to 200 micrometers and less than or equal to 1000 micrometers. Specifically, the thickness of the balancing block 6 in the vertical direction can be greater than or equal to 1 micrometer and less than or equal to 50 micrometers.

[0093] Referring again to Figure 2, because the thickness of the balance block 6 in the direction perpendicular to the rotary table 3 is small, the distance d6 from the center of mass of the balance block 6 to the rotation axis L of the rotary table 3 is small. Relying solely on the mass m6 of the balance block 6, the density of the balance block 6 may need to be particularly high to pull the center of mass of the rotating body (including the rotary table 3, micromirror 2, support column 5, and balance block 6) rotating around the rotation axis L to the rotation axis L. Therefore, in this embodiment, the center of mass of the balance block 6 is closer to the substrate 1 than the rotary table 3, that is, the center of mass of the balance block 6 is lower, which can increase d6, thereby balancing the center of mass of the rotating body rotating around the rotation axis L to the rotation axis L.

[0094] In one example, there are several ways to make the center of mass of the balancing block 6 closer to the substrate 1. For instance, as shown in Figures 5 and 6, the MEMS micromirror chip also includes a transition block 7, which is located between the rotary stage 3 and the balancing block 6. The mass of the transition block 7 is less than the mass of the balancing block 6. In this way, with the help of the transition block 7, the center of mass of the balancing block 6 is closer to the substrate 1 than that of the rotary stage 3. Moreover, since the mass of the transition block 7 is less than that of the balancing block 6, the center of mass of the transition block 7 and the balancing block 6 as a whole is also closer to the substrate 1. This is beneficial for pulling the center of mass of the rotating body (including the rotary stage 3, micromirror 2, support column 5, balancing block 6, and transition block 7) rotating around the rotation axis L to the rotation axis L.

[0095] Figures 5 and 6 are both schematic diagrams of the three-dimensional structure of the MEMS micromirror chip. Figure 6 is the front view of Figure 5 along the rotation axis L.

[0096] In one example, referring to Figure 5, the thickness of the lighter transition block 7 can be greater than or equal to the thickness of the heavier balance block 6 in the direction perpendicular to the rotary table 3. This helps to lower the position of the center of mass of the rotating body (including the rotary table 3, micromirror 2, support column 5, balance block 6 and transition block 7) rotating about the rotation axis L, so that the center of mass of the rotating body is near the rotation axis L.

[0097] In one example, because the thickness of the balance block 6 is relatively thin, in order to avoid the edge of the balance block 6 from turning or curling, accordingly, referring to Figure 5, in the horizontal plane parallel to the rotary table 3, the area of ​​the transition block 7 is greater than or equal to the area of ​​the balance block 6. That is, the bottom surface area of ​​the transition block 7 that contacts the balance block 6 is greater than or equal to the top surface area of ​​the balance block 6 that contacts the transition block 7.

[0098] In one example, the transition block 7 can be made of the same material as the substrate 1, for example, it can be made of single-crystal silicon. The transition block 7 can then be formed on the substrate 1 using semiconductor fabrication processes such as photolithography and etching. The fixing method between the balancing block 6 and the transition block 7 can refer to the above description and can be at least one of the following methods: evaporation, sputtering, electroplating, deposition, bonding, and adhesive bonding.

[0099] In another example, another way to make the center of mass of the balancing block 6 closer to the substrate 1 is as shown in Figure 7. The cross-sectional shape of the balancing block 6 along the direction perpendicular to the rotary table 3 is trapezoidal, and the area of ​​the top surface of the balancing block 6 is smaller than the area of ​​the bottom surface. The top surface of the balancing block 6 is the surface closer to the rotary table 3, and the bottom surface of the balancing block 6 is the surface closer to the substrate 1. This method of making the top mass of the balancing block 6 smaller than the bottom mass also achieves the goal of making the center of mass of the balancing block 6 closer to the substrate 1.

[0100] In another example, another way to achieve a centroid of the balancing block 6 closer to the substrate 1 is, as shown in Figure 8, to have a multi-layered structure. The multiple layers of the balancing block 6 are stacked sequentially along a direction perpendicular to the rotating stage 3, and the density of these multiple layers increases as they move away from the rotating stage 3. That is, the density of each layer in the multi-layered structure of the balancing block 6 gradually increases as it moves from the rotating stage 3 towards the substrate 1. This also achieves a centroid of the balancing block 6 closer to the substrate 1.

[0101] The above describes the application of counterweight 6 on a single-axis MEMS micromirror chip. Counterweight 6 can also be applied to a dual-axis MEMS micromirror chip.

[0102] (ii) MEMS micromirror chip with dual rotation axes.

[0103] Figures 9 to 11 show schematic diagrams of the structure of a MEMS micromirror chip with dual rotation axes. Figures 9 and 10 are three-dimensional schematic diagrams of the MEMS micromirror chip with dual rotation axes, and Figure 11 is a front view of Figure 9 along the first rotation axis L1.

[0104] Referring to Figures 9 and 10, in order to achieve a dual axis of rotation, the rotary table 3 includes a first rotating part 31 and a second rotating part 32 that are coplanar, the cantilever beam 4 includes a first cantilever beam 41 and a second cantilever beam 42, and the anchor point 8 also includes a first anchor point 81 and a second anchor point 82.

[0105] Referring to Figure 10, the first side of the first rotating part 31 is fixedly connected to a first anchor point 81 via a first cantilever beam 41, and the second side of the first rotating part 31 is fixedly connected to another first anchor point 81 via another first cantilever beam 41. The first and second sides of the first rotating part 31 are opposite each other, and the centerlines of the two first cantilever beams 41 and the centerline of the first rotating part 31 are collinear. The straight line containing these three lines is the rotation axis of the first rotating part 31 (denoted as the first rotation axis L1). Continuing to refer to Figure 10, the third and fourth sides of the first rotating part 31, which are opposite each other, both have movable comb teeth 33. The movable comb teeth 33 on both sides of the first rotating part 31 are symmetrically distributed about the first rotation axis L1.

[0106] Referring to Figure 10, the first side of the second rotating part 32 is fixedly connected to a second anchor point 82 via a second cantilever beam 42, and the second side of the second rotating part 32 is fixedly connected to another second anchor point 82 via another second cantilever beam 42. The first and second sides of the second rotating part 32 are opposite to each other, and the centerlines of the two second cantilever beams 42 and the centerline of the second rotating part 32 are collinear. The straight line containing these three lines is the rotation axis of the second rotating part 32 (denoted as the second rotation axis L2). Continuing to refer to Figure 10, the third and fourth sides of the second rotating part 32, which are opposite to each other, both have movable comb teeth 33. The movable comb teeth 33 on both sides of the second rotating part 32 are symmetrically distributed about the second rotation axis L2.

[0107] The first rotation axis L1 and the second rotation axis L2 are perpendicular, allowing the rotary table 3 to rotate around any rotation axis in the horizontal plane. Because the rotary table 3 is fabricated using semiconductor technology, the first rotating part 31 is fabricated first, followed by the second rotating part 32. The first rotating part 31 is on the inner side, and the second rotating part 32 is on the outer side. Therefore, the first rotating part 31 is also called the inner rotary table, and the second rotating part 32 is also called the outer rotary table. The first rotation axis L1 is also called the inner axis, and the second rotation axis is also called the outer axis.

[0108] It should be noted that, due to manufacturing process limitations, the first anchor point 81 used to fix the first rotating part 31 is generally fixed to the second rotating part 32. Therefore, referring to Figure 10, the first rotating part 31 is surrounded by a frame 34, the first rotating part 31 is located in the frame 34, and the first anchor point 81 is on the frame 34. Thus, the first side of the first rotating part 31 is connected to the frame 34 through the first cantilever beam 41, and the second side of the first rotating part 31 is connected to the frame 34 through the first cantilever beam 41.

[0109] Referring again to Figure 10, the second rotating part 32 is located outside the frame 34, with one part on the third side of the first rotating part 31 and the other part on the fourth side of the first rotating part 31. These two parts of the second rotating part 32 are symmetrically distributed about the first rotation axis L1.

[0110] Based on the above-mentioned structural features of the rotary table 3, referring to Figure 10, when the first rotating part 31 rotates around the first rotation axis L1, the second rotating part 32 is relatively stationary. However, when the second rotating part 32 rotates around the second rotation axis L2, the first rotating part 31 will rotate synchronously. Moreover, the first cantilever beam 41 and the first anchor point 81 connected to the first rotating part 31 will also rotate synchronously.

[0111] Regarding the fixation of the micromirror 2 on the rotating stage 3, the micromirror 2 can be fixed to the first rotating part 31 via support columns 5, in which case the support columns 5 are arranged above the first rotating part 31 facing away from the substrate 1. Alternatively, the micromirror 2 can also be fixed to the second rotating part 32 via support columns 5, in which case the support columns 5 are arranged above the second rotating part 32 facing away from the substrate 1. Or, the micromirror 2 can also be fixed to both the first rotating part 31 and the second rotating part 32 via support columns 5, in which case a portion of the support columns 5 are fixed above the first rotating part 31, and the other portion are fixed above the second rotating part 32. In this embodiment, it is not limited whether the micromirror 2 is fixed to the first rotating part 31 or the second rotating part 32; the example used is that the support columns 5 are fixed to the first rotating part 31.

[0112] To improve the vibration resistance of the micromirror 2, it is necessary to ensure that the micromirror does not easily rotate around the first rotation axis L1 or the second rotation axis L2 under external impact. Therefore, the center of mass of the rotating body (denoted as the first rotating body) rotating around the first rotation axis L1 must be located on the first rotation axis L1, and the center of mass of the rotating body (denoted as the second rotating body) rotating around the second rotation axis L2 must be located on the second rotation axis L2. As shown in Figures 10 and 11, a balance block (denoted as the first balance block 61) is arranged below the first rotating part 31 at a position along the first rotation axis L1, and a balance block (denoted as the second balance block 62) is also arranged below the second rotating part 32 at a position along the second rotation axis L2.

[0113] For example, referring to FIG10, a first balancing block 61 is arranged below the first rotating part 31 of the rotary table 3 and along the first rotation axis L1, wherein the center line of the first balancing block 61 is parallel to the first rotation axis L1 and is positioned opposite each other in a direction perpendicular to the rotary table 3. Continuing to refer to FIG10, a second balancing block 62 is arranged below the second rotating part 32 of the rotary table 3 and along the second rotation axis L2, wherein the center line of the second balancing block 62 is parallel to the second rotation axis L2 and is positioned opposite each other in a direction perpendicular to the rotary table 3.

[0114] Referring again to Figure 10, the first rotating body includes a first rotating part 31, a support column 5 fixed on the first rotating part 31, a micromirror 2, and a first balancing block 61. The second rotating body includes the first rotating body, a first cantilever beam 41, a first anchor point 81, a second rotating part 32, and a second balancing block 62.

[0115] The first balancing block 61 is used to reduce the degree of swaying of the micromirror 2 around the first rotation axis L1. Therefore, in order to achieve mechanical balance, the mass of the first balancing block 61 satisfies the following formula: m61×d61+m31×d31=m2×d2+m5×d5, where m61 is the mass of the first balancing block 61, d61 is the distance from the center of mass of the first balancing block 61 to the first rotation axis L1, m2 is the mass of the micromirror 2, d2 is the distance from the center of mass of the micromirror 2 to the first rotation axis L1, m5 is the mass of the support column 5, and d5 is the distance from the center of mass of the support column 5 to the first rotation axis L1. The distance is 1, m31 is the sum of the masses of the first rotating part 31 and the connected comb teeth 33, and d31 is the distance from the center of mass of the first rotating part 31 and the connected comb teeth 33 as a whole to the first linear rotation axis L1. If the center of mass of the first rotating part 31 is on the first linear rotation axis L1, then d31 = 0. If the center of mass of the first rotating part 31 is above the first linear rotation axis L1 (i.e., towards the micromirror 2), then d31 is less than 0. If the center of mass of the first rotating part 31 is below the first linear rotation axis L1 (i.e., towards the first balance block 61), then d31 is greater than 0.

[0116] The second balancing block 62 and the first balancing block 61 work together to reduce the degree of swaying of the micromirror 2 around the second rotation axis L2. Therefore, in order to achieve mechanical balance, the masses of the first balancing block 61 and the second balancing block 62 satisfy the following relationship: m61×d61+m62×d62+m3×d3=m2×d2+m5×d5, where m62 represents the mass of the second balancing block 62, d62 represents the distance from the center of mass of the second balancing block 62 to the second rotation axis L2, and m3 represents the mass of the entire rotating stage 3 (including the two rotating parts, the moving comb teeth on the two rotating parts, the frame, and the two first anchor points 81 connected to the frame). Specifically, if the center of mass of the rotating stage 3 is on the second rotation axis L2, then d3=0; if the center of mass of the rotating stage 3 is above the second rotation axis L2 (i.e., towards the micromirror 2), then d3<0; and if the center of mass of the rotating stage 3 is below the second rotation axis L2 (i.e., towards the balancing block), then d3>0.

[0117] Of course, the balance block 6 can be arranged only below the first rotating part 31, and the balance block 6 can be omitted below the second rotating part 32. In this case, the balance block 6 is used to balance the first rotating body and reduce the degree of shaking of the micromirror 2 around the first rotation axis L1, and also to balance the second rotating body and reduce the degree of shaking of the micromirror 2 around the second rotation axis L2.

[0118] Similarly, the first balance block 61 can reduce the off-axis effect of the center of mass of the first rotating body deviating from the first rotation axis L1 by using a high-density material, and the second balance block 62 can reduce the off-axis effect of the center of mass of the second rotating body deviating from the second rotation axis L2 by using a high-density material. The materials of the first balance block 61 and the second balance block 62 can refer to the materials of the balance block 6 mentioned above, and will not be repeated. The fixing method and thickness of the first balance block 61 and the second balance block 62 on the rotary table 3 are also as described above, and will not be repeated.

[0119] Similarly, to bring the centroids of the first balancing block 61 and the second balancing block 62 closer to the substrate, the MEMS micromirror chip can also include a transition block 7. For example, referring to Figures 12 and 13, a first transition block 71 is arranged between the first rotating part 31 and the first balancing block 61, and a second transition block 72 is arranged between the second rotating part 32 and the second balancing block 62. Of course, this can also be achieved by making the first balancing block 61 and the second balancing block 62 trapezoidal in shape, or by making both the first balancing block 61 and the second balancing block 62 multilayer structures with a higher density closer to the substrate.

[0120] The above is an introduction to the dual-axis rotating MEMS micromirror chip.

[0121] In one example, whether it's a single-axis rotating MEMS micromirror chip or a dual-axis rotating MEMS micromirror chip, as shown in Figure 14, the number of micromirrors 2 can be multiple, arranged in an array. Referring to Figure 14, there are multiple micromirrors 2 and multiple rotating stages 3, with each micromirror 2 corresponding to a rotating stage 3. Each micromirror 2 is located on the substrate 1 via a rotating stage 3. For example, each rotating stage 3 is connected to the substrate 1 via a cantilever beam, and each micromirror 2 is fixed to a rotating stage 3 via a support column 5. Furthermore, the aforementioned balancing block 6 is arranged below each rotating stage 3 facing the substrate 1. In the direction perpendicular to the rotating stage, the substrate 1 has a surface at the position corresponding to each balancing block 6, and in the direction perpendicular to the rotating stage, there is a gap between the surfaces of the substrate 1 and the surfaces of each balancing block 6 facing each other, so that the rotation of the rotating stage 3 is not interfered with by the balancing block 6.

[0122] In this embodiment, the rotating stage of the MEMS micromirror chip has a counterweight arranged below it, facing away from the micromirror. This ensures that the center of mass of the rotating body, which rotates around the axis of rotation, is near the axis of rotation, thereby improving the vibration resistance of the micromirror. When the MEMS micromirror chip is subjected to impacts from the external environment, the micromirror is less prone to shaking, thus improving the accuracy of the MEMS micromirror chip. Moreover, although a counterweight is arranged between the rotating stage and the substrate, the substrate still has a surface in the direction perpendicular to the rotating stage and opposite to the counterweight. This ensures the hermeticity of the MEMS micromirror chip.

[0123] This embodiment also provides a micromirror device, specifically a MEMS micromirror device. Figure 15 shows a schematic diagram of the MEMS micromirror device. Referring to Figure 15, the MEMS micromirror device includes a substrate 100, a light-transmitting cover (not shown in Figure 15), and the aforementioned MEMS micromirror chip 200. The MEMS micromirror chip 200 is located on the surface of the substrate 100. The light-transmitting cover can be dome-shaped, with its walls fixed to the substrate 100, forming a receiving cavity between the cover and the substrate 100. All micromirrors 2 of the MEMS micromirror chip 200 are located within this cavity. Alternatively, the dome-shaped light-transmitting cover can be fixed to the substrate 1 of the MEMS micromirror chip 200, forming a receiving cavity between the cover and the substrate 1, with all micromirrors 2 located within this cavity. The substrate 100 has a driving circuit to input a driving voltage to the driving mechanism of the MEMS micromirror chip, driving the rotating stage 3 to rotate the micromirrors 2.

[0124] This embodiment also provides an optical device, which can be an optical switch, an optical switching device, a wavelength selective switch, or a radar, etc. The optical device includes a signal transmitter and the aforementioned MEMS micromirror device. The signal transmitter can be a laser, such as a semiconductor laser. The micromirror of the MEMS micromirror device is located in the transmission optical path of the signal transmitter. In this way, the optical signal emitted by the signal transmitter is incident on the micromirror and reflected outward by the micromirror.

[0125] In one example, the optical device may further include a signal receiver, which may be a detector used to receive optical signals, for example, optical signals emitted by another optical device. The signal receiver may receive the optical signal emitted by the other optical device directly, or it may receive the optical signal emitted by the other optical device via a micromirror of a micromirror device.

[0126] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A micromirror chip, characterized in that, It includes a substrate (1), a micromirror (2), a rotating stage (3), a cantilever beam (4), a support column (5), and a balance block (6); The rotating stage (3) is connected to the substrate (1) via the cantilever beam (4), the micromirror (2) is fixed above the rotating stage (3) via the support column (5), and the balance block (6) is fixed below the rotating stage (3). The substrate (1) has a surface at a position opposite to the balance block (6) in the arrangement direction of the support column (5), the rotating stage (3) and the balance block (6), and there is a gap between the surfaces of the substrate (1) and the balance block (6) facing each other in the arrangement direction.

2. The micromirror chip according to claim 1, characterized in that, The balance block (6) is fixed below the rotary table (3) and along the rotation axis of the rotary table (3).

3. The micromirror chip according to claim 2, characterized in that, The rotating platform (3) has a first rotation axis and a second rotation axis. The balance block (6) is fixed below the rotating platform (3) and along both the first rotation axis and the second rotation axis.

4. The micromirror chip according to claim 2 or 3, characterized in that, The centerline of the balance block (6) is parallel to the corresponding rotation axis, and the plane in which it is located is parallel to the arrangement direction of the support column (5), the rotating table (3) and the balance block (6).

5. The micromirror chip according to any one of claims 1 to 4, characterized in that, The micromirror (2) includes a substrate and a reflective layer located on the surface of the substrate. The density of the balance block (6) is greater than or equal to twice the density of the substrate of the micromirror (2), and also greater than or equal to twice the density of the support column (5).

6. The micromirror chip according to any one of claims 1 to 5, characterized in that, The thickness of the balance block (6) is less than half the thickness of the substrate (1), wherein the thickness of the balance block (6) and the substrate (1) are both dimensions in the arrangement direction of the support column (5), the rotating stage (3) and the balance block (6).

7. The micromirror chip according to any one of claims 1 to 6, characterized in that, The thickness of the balance block (6) is greater than or equal to 1 micrometer and less than or equal to 50 micrometers. The thickness of the balance block (6) is the dimension in the arrangement direction of the support column (5), the rotating table (3) and the balance block (6).

8. The micromirror chip according to any one of claims 1 to 7, characterized in that, The center of mass of the balance block (6) is close to the substrate (1) relative to the rotating stage (3).

9. The micromirror chip according to claim 8, characterized in that, The micromirror chip also includes a transition block (7), which is arranged between the rotary table (3) and the balance block (6). The mass of the transition block (7) is less than the mass of the balance block (6).

10. The micromirror chip according to claim 9, characterized in that, The cross-sectional shape of the balance block (6) in the direction perpendicular to the corresponding rotation axis is trapezoidal, and the top surface of the balance block (6) is close to the rotating stage (3), and the bottom surface is close to the substrate (1), wherein the area of ​​the top surface of the balance block (6) is smaller than the area of ​​the bottom surface.

11. The micromirror chip according to claim 9, characterized in that, The balance block (6) has a multi-layer structure. The arrangement direction of the multi-layer balance block (6) is parallel to the arrangement direction of the support column (5), the rotating platform (3) and the balance block (6). The density of each layer in the multi-layer increases as it moves away from the rotating platform (3).

12. The micromirror chip according to any one of claims 1 to 11, characterized in that, The balance block (6) is made of metal.

13. The micromirror chip according to any one of claims 1 to 12, characterized in that, The number of micromirrors (2) and the number of rotating stages (3) are both multiple, and the micromirrors (2) and the rotating stages (3) correspond one-to-one, with the multiple micromirrors (2) arranged in an array.

14. A micromirror device, characterized in that, The micromirror device includes a substrate, a light-transmitting cover plate, and a micromirror chip according to any one of claims 1 to 13; The micromirror chip is located on the surface of the substrate, and the light-transmitting cover plate is fixed to the substrate or the substrate of the micromirror chip to form a receiving cavity, wherein the micromirror (2) of the micromirror chip is located in the receiving cavity.

15. An optical device, characterized in that, The optical device includes an optical signal transmitter and a micromirror device as described in claim 14. The optical signal emitted by the optical signal transmitter is incident on the micromirror (2) of the micromirror device and reflected outward via the micromirror (2).

16. The optical device according to claim 15, characterized in that, The optical device also includes a signal receiver for receiving optical signals.

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