Optical noise suppressor, manufacturing method and application

Abstract

The invention provides an optical noise suppressor, a manufacturing method and application, the optical noise suppressor comprises a substrate, a piezoelectric driving structure and a top cover, the substrate is internally provided with a clearance space vertically penetrating through the substrate, the clearance space is internally provided with a grating structure, and the grating structure is connected with the substrate through a cantilever beam structure; the piezoelectric driving structure is located above the cantilever beam structure and comprises a bottom electrode metal layer, a piezoelectric film layer and a top electrode metal layer which are stacked from bottom to top; the top cover is located above the substrate and is in bonding connection with the substrate, a reflecting layer is arranged on the lower surface of the top cover, the projection of the reflecting layer on the substrate covers the grating structure, the piezoelectric driving structure can drive the cantilever beam structure to deform after applying voltage, and then the distance between the grating structure and the top cover is changed. The distance between the grating structure and the reflecting layer can be precisely regulated and controlled through voltage driving, the reference light intensity can be regulated and controlled and monitored in real time, and the advantages of full automation and high precision are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic detection and relates to an optical noise suppressor, a manufacturing method and an application thereof. Background Art

[0002] With the rapid development of laser technology, lasers have been widely used in scientific and technological fields such as quantum optics, national defense technology, and precision measurement. In scientific research on high-precision measurement, the running laser will couple mechanical vibration noise, thermal noise, etc., causing the light field fluctuations to become background noise, limiting the sensitivity of the measurement device. The commonly used method is to construct a closed-loop control of the laser drive current, but the control accuracy of the current source itself is limited, and the noise caused by temperature drift cannot be eliminated.

[0003] The noise in the nitrogen vacancy (NV) color center magnetic detection system in diamond crystals mainly includes laser noise, microwave frequency and power noise, and electronic noise. Laser noise mainly includes laser amplitude noise and phase noise. Laser amplitude noise is the light field fluctuation caused by the instability of laser output power. It will directly affect the detected fluorescence signal in the time domain. Studies have found that the laser noise accounts for 0.1-1%, while the background noise is 0.001%. Therefore, for the NV color center magnetic detection system, laser noise is one of the main noises of NV color center magnetic sensing. There are many ways to reduce laser noise by common-mode suppression. For example, a beam splitter is used to split the laser into a spatial reference light and a detection light, and two photodetectors of the same model are used for sampling for 1 second. The ratio of the average values ​​of the two signals is obtained, and the mean and variance of the two signals are kept consistent by adjusting the light diffuser and the amplification factor of the reference light detector based on software before differentiation. There are also studies that increase the magnetic detection sensitivity by 10 times by splitting the laser to excite two diamond fluorescences, using optical fiber coupling to enter a balanced detector, and adjusting the coupling efficiency to achieve numerical equality for differentiation. These common-mode suppression methods, whether it is to differentiate the spatial light or adjust the coupling efficiency, all involve manually adjusting the optical devices and are not compatible with micromachining technology.

[0004] Therefore, how to provide an optical noise suppressor, a manufacturing method and an application to realize automatic control of the reference light and achieve compatibility with micro-machining technology has become a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an optical noise suppressor, a manufacturing method and an application, so as to solve the problems in the prior art of low modulation accuracy of manually modulating the reference light intensity and incompatibility with micromachining technology.

[0006] To achieve the above object and other related objects, the present invention provides an optical noise suppressor, comprising:

[0007] A substrate, the substrate comprising a bottom silicon layer, a middle oxide layer and a top silicon layer stacked from bottom to top, the substrate being provided with an air-avoiding space vertically penetrating the substrate, the air-avoiding space located in the top silicon layer region being provided with a grating structure and a cantilever beam structure, the grating structure being connected to the substrate via the cantilever beam structure;

[0008] A piezoelectric driving structure is located above the cantilever beam structure, and the piezoelectric driving structure includes a bottom electrode metal layer, a piezoelectric film layer and a top electrode metal layer stacked from bottom to top;

[0009] A top cover is located above the base and bonded to the base, a reflective layer is provided on the lower surface of the top cover, and the projection of the reflective layer on the base covers the grating structure, wherein after the piezoelectric drive structure applies a voltage, the cantilever beam structure can be driven to deform, thereby changing the distance between the grating structure and the top cover.

[0010] Optionally, the piezoelectric driving structure also extends above the top silicon layer, and a bottom electrode lead-out electrode and a top electrode lead-out electrode are arranged in the piezoelectric driving structure located above the top silicon layer, wherein the bottom electrode lead-out electrode is electrically connected to the bottom electrode metal layer, and the top electrode lead-out electrode is electrically connected to the top electrode metal layer.

[0011] Optionally, a cross-sectional area of ​​the top cover is smaller than a cross-sectional area of ​​the substrate, and the top cover does not cover the bottom electrode lead-out electrode and the top electrode lead-out electrode.

[0012] Optionally, a first bonding metal layer connected to the substrate is arranged above the substrate, and a second bonding metal layer connected to the top cover is arranged on the lower side of the top cover, wherein the first bonding metal layer is bonded to the second bonding metal layer so that the substrate is bonded to the top cover.

[0013] Optionally, the distance between the grating structure and the reflective layer ranges from 0.5 to 4 um.

[0014] The present invention also provides a method for manufacturing an optical noise suppressor, comprising the following steps:

[0015] Providing a substrate, the substrate comprising a bottom silicon layer, an intermediate oxide layer and a top silicon layer stacked from bottom to top, forming a piezoelectric driving structure on the substrate, the piezoelectric driving structure comprising a bottom electrode metal layer, a piezoelectric film layer and a top electrode metal layer stacked from bottom to top;

[0016] Etching the top silicon layer to form a grating structure and a cantilever beam structure in the top silicon layer, wherein the grating structure is connected to the top silicon layer through the cantilever beam structure, wherein the piezoelectric drive structure is located above the cantilever beam structure, and etching the bottom silicon layer and the middle oxide layer to form a back cavity, wherein the back cavity exposes the grating structure and the cantilever beam structure;

[0017] A top cover is provided, a reflective layer is formed on the lower surface of the top cover, and the top cover is bonded to the substrate, wherein the projection of the reflective layer on the substrate covers the grating structure, wherein after the voltage is applied to the piezoelectric drive structure, the cantilever beam structure can be driven to deform, thereby changing the distance between the grating structure and the top cover.

[0018] Optionally, the piezoelectric driving structure also extends above the top silicon layer. After the piezoelectric driving structure is formed, it also includes the step of forming a bottom electrode lead-out electrode and a top electrode lead-out electrode in the piezoelectric driving structure located above the top silicon layer, wherein the bottom electrode lead-out electrode is electrically connected to the bottom electrode metal layer, and the top electrode lead-out electrode is electrically connected to the top electrode metal layer.

[0019] Optionally, a cross-sectional area of ​​the top cover is smaller than a cross-sectional area of ​​the substrate, and the top cover does not cover the bottom electrode lead-out electrode and the top electrode lead-out electrode.

[0020] Optionally, a first bonding metal layer connected to the substrate is formed above the substrate, and a second bonding metal layer connected to the top cover is formed on the lower side of the top cover, wherein the first bonding metal layer is bonded to the second bonding metal layer so that the substrate is bonded to the top cover.

[0021] The present invention also provides an application of an optical noise suppressor, comprising the following steps:

[0022] Building a test platform, the test platform comprising a laser, a beam splitter, a diamond, a balanced detector, a signal generator, and the optical noise suppressor described in any one of the above items;

[0023] The laser is emitted by the laser, and the laser is divided into detection light and reference light by the beam splitter, wherein the detection light is irradiated to the diamond to generate a fluorescence signal, and the fluorescence signal is received by the first port of the balanced detector. The signal generator controls the change of the distance between the grating structure and the reflective layer of the optical noise suppressor so that the reference light is irradiated to the optical noise suppressor to generate a periodic diffraction signal, and the diffraction signal is received by the second port of the balanced detector. When the fluorescence signal and the diffraction signal are at the same order of magnitude, differential common mode suppression is performed.

[0024] As described above, in the optical noise suppressor, manufacturing method and application of the present invention, the spacing between the grating structure and the reflective layer can be accurately controlled by voltage driving, the reference light intensity can be controlled and monitored in real time, and it has the advantages of full automation and high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a cross-sectional schematic diagram of an optical noise suppressor according to a first embodiment of the present invention.

[0026] Figure 2 It is a top view of the first bonding metal layer disposed on the substrate in the first embodiment of the present invention.

[0027] Figure 3 Shown is a bottom view of the top cover in the first embodiment of the present invention.

[0028] Figure 4 It shows the optical interference principle diagram of the optical noise suppressor in the first embodiment of the present invention.

[0029] Figure 5 It is a schematic diagram showing the variation of the intensity of the positive first-order diffraction spot with the spacing in the first embodiment of the present invention.

[0030] Figure 6 The figure shows the displacement change of the grating structure after the voltage is applied to the piezoelectric driving structure in the first embodiment of the present invention.

[0031] Figure 7 It shows a process flow chart of a method for manufacturing an optical noise suppressor according to a second embodiment of the present invention.

[0032] Figure 8 It is a schematic diagram showing a piezoelectric driving structure formed on a top silicon layer in the second embodiment of the present invention.

[0033] Fig. 9 It is a schematic diagram showing the etching of the top silicon layer to form a grating structure and a cantilever beam structure in the second embodiment of the present invention.

[0034] Fig.10 It is a schematic diagram showing providing a top cover and bonding the top cover to a substrate in the second embodiment of the present invention.

[0035] Fig.11 Shown is a schematic diagram of a test platform according to Embodiment 3 of the present invention.

[0036] Component number description

[0037] 1 Base

[0038] 100 Top silicon layer

[0039] 101 Intermediate Oxide Layer

[0040] 102 bottom silicon layer

[0041] 103 Back cavity

[0042] 2 Grating structure

[0043] 3 Cantilever beam structure

[0044] 4 Piezoelectric drive structure

[0045] 400 Bottom electrode metal layer

[0046] 401 Piezoelectric film layer

[0047] 402 top electrode metal layer

[0048] 403 bottom electrode lead-out electrode

[0049] 404 Top electrode lead-out electrode

[0050] 5 Insulation layer

[0051] 6 First bonding metal layer

[0052] 7 Top cover

[0053] 700 Top silicon layer

[0054] 701 Intermediate Oxide Layer

[0055] 702 bottom silicon layer

[0056] 8 Reflection layer

[0057] 9 Second bonding metal layer

[0058] 10 Oxide layer

[0059] 11 Reference Light

[0060] 12 Laser

[0061] 13 Beam splitter

[0062] 14 Diamond

[0063] 15 Balanced Detector

[0064] 16 Signal Generator

[0065] 17 Optical Noise Suppressor

[0066] 18 Filter

[0067] 19 Focusing lens

[0068] 20 Reflector

[0069] Steps S1 to S3 DETAILED DESCRIPTION

[0070] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0071] See also Figures 1 to 11 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0072] Embodiment 1

[0073] This embodiment provides an optical noise suppressor. Figure 1 , which is a schematic cross-sectional view of the optical noise suppressor, includes a substrate 1, a piezoelectric driving structure 4 and a top cover 7, wherein the substrate 1 includes a bottom silicon layer 102, an intermediate oxide layer 101 and a top silicon layer 100 stacked from bottom to top, and an air-avoiding space vertically penetrating the substrate 1 is provided in the substrate 1, and a grating structure 2 and a cantilever beam structure 3 are provided in the air-avoiding space located in the region of the top silicon layer 100, and the grating structure 2 is connected to the substrate 1 through the cantilever beam structure 3; the piezoelectric driving structure 4 is located in the cantilever beam structure 3. Above the cantilever beam structure 3, the piezoelectric driving structure 4 includes a bottom electrode metal layer 400, a piezoelectric film layer 401 and a top electrode metal layer 402 stacked from bottom to top; the top cover 7 is located above the substrate 1 and bonded to the substrate 1, and a reflective layer 8 is provided on the lower surface of the top cover 7, and the projection of the reflective layer 8 on the substrate 1 covers the grating structure 2. After the voltage is applied to the piezoelectric driving structure 4, it can drive the cantilever beam structure 3 to deform, thereby changing the distance between the grating structure 2 and the top cover 7.

[0074] As an example, the base 1 adopts an SOI substrate, the grating structure 2 and the cantilever beam structure 3 are formed based on the top silicon layer 100, and a back cavity 103 is arranged in the middle oxide layer 101 and the bottom silicon layer 102, and the back cavity 103 exposes the grating structure 2 and the cantilever beam structure 3 so that the laser can reach the grating structure 2 through the back cavity 103.

[0075] As an example, an insulating layer 5 is provided on the upper surface of the top silicon layer 100 to insulate and isolate the piezoelectric driving structure 4 from the substrate 1, and the piezoelectric driving structure 4 extends from the cantilever beam structure 3 area to the top silicon layer 100 area, wherein the piezoelectric driving structure 4 located in the cantilever beam structure 3 area is used to provide power for the deformation of the cantilever beam structure 3, and the piezoelectric driving structure 4 located in the top silicon layer 100 area is used for electrode lead-out, and the piezoelectric driving structure 4 located in the top silicon layer 100 area is provided with a bottom electrode lead-out electrode 403 and a top electrode lead-out electrode 404, the bottom electrode lead-out electrode 403 is electrically connected to the bottom electrode metal layer 400, and the top electrode lead-out electrode 404 is electrically connected to the top electrode metal layer 402.

[0076] As an example, a first bonding metal layer 6 is arranged on the top silicon layer 100, and the first bonding metal layer 6 includes metal materials such as aluminum, germanium, gold, and tin, wherein a stacked bottom electrode metal layer 400, a piezoelectric film layer 401, and a top electrode metal layer 402 are arranged below the first bonding metal layer 6, so that the top of the first bonding metal layer 6 is higher than the height of the piezoelectric driving structure 4.

[0077] As an example, see Figure 2 , showing a top view of the substrate, the cantilever beam structure 3 is a six-axis structure, evenly distributed on the periphery of the grating structure 2, so that the cantilever beam structure 3 can evenly drive the grating structure 2 to move when deformed; and the cantilever beam structure 3 is spaced apart from the axis structures, reducing the air damping of the sensing process, thereby reducing the impact of noise and improving the overall signal-to-noise ratio. Of course, in other examples, the cantilever beam structure 3 can also be set to a two-axis structure, a three-axis structure, a four-axis structure, a five-axis structure, a seven-axis structure, an eight-axis structure, etc., which is not limited to this embodiment.

[0078] As an example, the top cover 7 adopts an SOI substrate, including a top silicon layer 700, an intermediate oxide layer 701 and a bottom silicon layer 702 stacked from top to bottom, and a second bonding metal layer 9 is provided on the lower side of the top cover 7, wherein the reflective layer 8 is located directly above the grating structure 2, and the second bonding metal layer 9 corresponds to the position of the first bonding metal layer 6, and the first bonding metal layer 6 is bonded to the second bonding metal layer 9, so that the substrate 1 is bonded to the top cover 7.

[0079] As an example, an oxide layer 10 is provided on the lower surface of the top cover 7 , and the oxide layer 10 is used to insulate and isolate the top cover 7 from the reflective layer 8 and the second bonding metal layer 9 .

[0080] As an example, see Figure 3, showing a bottom view of the top cover, the cross-sectional area of ​​the top cover 7 is smaller than the cross-sectional area of ​​the substrate 1, and after the top cover 7 is bonded to the substrate 1, the top cover 7 does not cover the bottom electrode lead-out electrode 403 and the top electrode lead-out electrode 404, so as to facilitate the wire bonding connection between the piezoelectric driving structure 4 and external devices.

[0081] As an example, see Figure 4 , which is a schematic diagram of the optical interference principle of the optical noise suppressor. When the reference light 11 is incident vertically, a part of the light is reflected and diffracted by the grating structure 2, and the other part of the light passes through the grating structure 2 and reaches the reflective layer 8, and then is reflected and diffracted by the grating structure 2 again. Therefore, two groups of diffracted lights with phase difference are generated to interfere constructively or destructively, thereby generating multi-order interference spots (such as 0th order, ±1st order, ±2nd order, etc.). The intensity of each order spot can be derived based on the Fraunhofer diffraction theory. Taking the ±1st diffraction order as an example, the intensity of the ±1st diffraction order is:

[0082]

[0083] Among them, I in is the light intensity of the reference light 11, is the incident wavelength value, and d is the distance between the grating structure 2 and the reflective layer 8. It can be analyzed that by adjusting the distance d between the grating structure 2 and the reflective layer 8, the size of the ±1-order diffraction light intensity can be adjusted, and the intensity amplitude of the sinusoidal change can be adjusted with high precision. That is, by adjusting the distance d between the grating structure 2 and the reflective layer 8, the positive first-order light intensity with light and dark changes is obtained, and the light intensity control range is designed according to the intensity value of the signal to be measured, ensuring that the order of magnitude of the first-order diffraction light intensity amplitude is in the same order of magnitude as the amplitude intensity of the signal to be measured.

[0084] As an example, after a voltage is applied to the piezoelectric driving structure 4 , the cantilever beam structure 3 is deformed, thereby driving the grating structure 2 to move, thereby adjusting the distance between the grating structure 2 and the reflective layer 8 .

[0085] As an example, the change in the distance between the grating structure 2 and the reflective layer 8 during the change in the positive first-order diffraction light intensity from the minimum light intensity to the maximum light intensity is defined as the minimum braking distance, and the distance range over which the piezoelectric driving structure 4 drives the grating structure 2 to move is greater than the minimum braking distance to ensure that the piezoelectric driving structure 4 generates a periodically changing light intensity amplitude when driving the grating structure 2 to move.

[0086] As an example, the duty cycle of the grating structure 2 in this embodiment is 0.5, the period is 4um, and the thickness is 5um. The simulation is performed, and the schematic diagram of the change of the positive first-order diffraction spot intensity with the spacing is as follows: Figure 5As shown, the spacing value is scanned on the basis of maximizing the grating diffraction efficiency, and the periodically changing diffraction first-order light intensity amplitude is obtained, and the minimum braking distance is 135nm; Figure 6 As shown, when a voltage of 0-80V is applied to the piezoelectric drive structure 4, the quasi-static displacement of the grating structure 2 is 0-250nm, and has a high linearity, that is, the structure designed in the present application can accurately control the spacing between the grating structure and the reflective layer through voltage drive, and the reference light intensity can be adjusted and monitored in real time. Compared with the traditional method of manually modulating the reference light intensity, the optical noise suppressor of this embodiment is driven by voltage and has the advantages of full automation and high precision.

[0087] As described above, the optical noise suppressor of this embodiment can accurately adjust the distance between the grating structure and the reflective layer through voltage driving, and can adjust and monitor the reference light intensity in real time, which has the advantages of full automation and high precision.

[0088] Embodiment 2

[0089] This embodiment provides a method for manufacturing an optical noise suppressor, which is used to manufacture the optical noise suppressor described in the first embodiment. Figure 7 , which is shown as a process flow chart of the production method, comprising the following steps:

[0090] S1: providing a substrate, wherein the substrate comprises a bottom silicon layer, an intermediate oxide layer and a top silicon layer stacked from bottom to top, and forming a piezoelectric driving structure on the substrate, wherein the piezoelectric driving structure comprises a bottom electrode metal layer, a piezoelectric film layer and a top electrode metal layer stacked from bottom to top;

[0091] S2: etching the top silicon layer to form a grating structure and a cantilever beam structure in the top silicon layer, wherein the grating structure is connected to the top silicon layer through the cantilever beam structure, wherein the piezoelectric drive structure is located above the cantilever beam structure, and etching the bottom silicon layer and the middle oxide layer to form a back cavity, wherein the back cavity exposes the grating structure and the cantilever beam structure;

[0092] S3: Provide a top cover, form a reflective layer on the lower surface of the top cover, bond the top cover to the substrate, the projection of the reflective layer on the substrate covers the grating structure, wherein after the voltage is applied to the piezoelectric drive structure, the cantilever beam structure can be driven to deform, thereby changing the distance between the grating structure and the top cover.

[0093] First, see Figure 8, perform step S1: provide a substrate 1, the substrate 1 includes a bottom silicon layer 102, an intermediate oxide layer 101 and a top silicon layer 100 stacked from bottom to top, and form a piezoelectric driving structure 4 on the substrate 1, the piezoelectric driving structure 4 includes a bottom electrode metal layer 400, a piezoelectric film layer 401 and a top electrode metal layer 402 stacked from bottom to top.

[0094] As an example, the substrate 1 adopts an SOI substrate. Before forming the piezoelectric driving structure 4, it also includes a step of forming an insulating layer 5 on the top silicon layer 100. The insulating layer 5 includes a silicon dioxide layer. The insulating layer 5 is used to insulate and isolate the piezoelectric driving structure 4 from the substrate 1.

[0095] As an example, the piezoelectric driving structure 4 is formed on the insulating layer 5 by a deposition process, wherein a stacked bottom electrode metal layer 400, a piezoelectric film layer 401 and a top electrode metal layer 402 are also formed in the subsequent bonding area, so that the top of the subsequent first bonding metal layer 6 is higher than the top of the piezoelectric driving structure 4.

[0096] As an example, after the piezoelectric driving structure 4 is formed, it also includes the step of using a deposition process and a patterning process to form a bottom electrode lead-out electrode 403 and a top electrode lead-out electrode 404, wherein the bottom electrode lead-out electrode 403 is electrically connected to the bottom electrode metal layer 400, and the top electrode lead-out electrode 404 is electrically connected to the top electrode metal layer 402.

[0097] As an example, after forming the bottom electrode lead-out electrode 403 and the top electrode lead-out electrode 404, a deposition process and a patterning process are used to form the first bonding metal layer 6 at a preset position of the top electrode metal layer 402 in the bonding area. The material of the first bonding metal layer 6 includes metal materials such as aluminum, germanium, gold, and tin.

[0098] Next, see Fig. 9 , perform step S2: etching the top silicon layer 100, forming a grating structure 2 and a cantilever beam structure 3 in the top silicon layer 100, the grating structure 2 is connected to the top silicon layer 100 through the cantilever beam structure 3, wherein the piezoelectric drive structure 4 is located above the cantilever beam structure 3, and etching the bottom silicon layer 102 and the middle oxide layer 101 to form a back cavity 103, and the back cavity 103 reveals the grating structure 2 and the cantilever beam structure 3.

[0099] As an example, the insulating layer 5 is patterned by a photolithography process, and the top silicon layer 100 is etched using the patterned insulating layer 5 as a hard mask to form the grating structure 2 and the cantilever beam structure 3. Figure 2, the cantilever beam structure 3 is a six-axis structure, evenly distributed on the periphery of the grating structure 2, so that the cantilever beam structure 3 can evenly drive the grating structure 2 to move when deformed; and the cantilever beam structure 3 is spaced apart from the axis structures, reducing the air damping of the sensing process, thereby reducing the impact of noise and improving the overall signal-to-noise ratio. Of course, in other examples, the cantilever beam structure 3 can also be set to a two-axis structure, a three-axis structure, a four-axis structure, a five-axis structure, a seven-axis structure, an eight-axis structure, etc., which is not limited to this embodiment.

[0100] As an example, the back cavity 103 is formed in the middle oxide layer 101 and the bottom silicon layer 102 by an etching process, and the back cavity 103 exposes the grating structure 2 and the cantilever beam structure 3 so that the laser can reach the grating structure 2 through the back cavity 103 .

[0101] Next, see Fig.10 , execute step S3: provide a top cover 7, form a reflective layer 8 on the lower surface of the top cover 7, bond the top cover 7 to the substrate 1, the projection of the reflective layer 8 on the substrate 1 covers the grating structure 2, wherein after the piezoelectric driving structure 4 applies a voltage, it can drive the cantilever beam structure 3 to deform, thereby changing the distance between the grating structure 2 and the top cover 7.

[0102] As an example, the top cover 7 adopts an SOI substrate, including a top silicon layer 700, an intermediate oxide layer 701 and a bottom silicon layer 702 stacked from top to bottom. Before forming the reflective layer 8, it also includes a step of forming an oxide layer 10 on the lower surface of the bottom silicon layer 702. The oxide layer 10 is used to insulate and isolate the reflective layer 8 and the top cover 7.

[0103] As an example, a second bonding metal layer 9 is formed on the lower side of the top cover 7 by using a deposition process and an etching process, and the second bonding metal layer 9 corresponds to the position of the first bonding metal layer 6. A reflection layer 8 is formed by using a deposition process and an etching process, and the reflection layer 8 is a metal reflection layer.

[0104] As an example, see Figure 3 The cross-sectional area of ​​the top cover 7 is smaller than the cross-sectional area of ​​the substrate 1. After the top cover 7 is bonded to the substrate 1, the top cover 7 does not cover the bottom electrode lead-out electrode 403 and the top electrode lead-out electrode 404, so as to facilitate the wire bonding connection between the piezoelectric driving structure 4 and external devices.

[0105] As an example, the second bonding metal layer 9 and the first bonding metal layer 6 are bonded to each other so that the substrate 1 and the top cover 7 are bonded to each other. The spacing between the grating structure 2 and the cover plate 7 can be controlled by a high-precision bonding process, and the process tolerance is ±0.5um.

[0106] As described above, the manufacturing method of the optical noise suppressor of this embodiment is compatible with the micromachining process. The spacing between the grating structure and the reflective layer can be precisely controlled by voltage driving, and the reference light intensity can be controlled and monitored in real time, which has the advantages of full automation and high precision.

[0107] Embodiment 3

[0108] This embodiment provides an application of an optical noise suppressor, including the following steps:

[0109] 1) If Fig.11 As shown, a test platform is constructed, the test platform includes a laser 12, a beam splitter 13, a diamond 14, a balanced detector 15, a signal generator 16, and the optical noise suppressor 17 described in the first embodiment;

[0110] 2) The laser 12 emits laser light, which is divided into detection light and reference light by the beam splitter 13, wherein the detection light is irradiated to the diamond 14 to generate a fluorescence signal, and the fluorescence signal is received by the first port of the balanced detector 15, and the signal generator 16 controls the distance between the grating structure of the optical noise suppressor 17 and the reflective layer to change, so that the reference light is irradiated to the optical noise suppressor 17 to generate a periodic diffraction signal, and the diffraction signal is received by the second port of the balanced detector 15, and differential common mode suppression is performed when the fluorescence signal and the diffraction signal are at the same order of magnitude.

[0111] As an example, the fluorescence signal is filtered by a filter 18 , then focused by a focusing lens 19 , and received by the first port of the balanced detector 15 .

[0112] As an example, the diffraction signal is received by the second port of the balanced detector 15 after being reflected by the reflector 20 .

[0113] As an example, the signal generator 16 applies a DC voltage signal to the piezoelectric drive structure of the optical noise suppressor 17 to drive the grating structure to generate displacement, and reads the voltage amplitude change of the positive first-order diffraction spot after photoelectric conversion at the second port of the balanced detector 15. After adjusting the voltage value so that the readings of the two ports of the balanced detector 15 are equal, common-mode suppression difference is performed. There is an optical noise signal in the reference light, and the detection light has both the signal to be measured and the laser noise signal. After differential amplification of the two, the signal-to-noise ratio of the measurement will be improved, the parasitic laser noise part in the fluorescence signal will be eliminated, and the sensitivity of the magnetic detection sensor will be improved. It can be applied to magnetic field measurement at the pT level, and has great development potential in the fields of biomedicine, materials science, energy detection, etc.

[0114] In summary, the optical noise suppressor, manufacturing method and application of the present invention can accurately control the spacing between the grating structure and the reflective layer through voltage driving, and can control and monitor the reference light intensity in real time, which has the advantages of full automation and high precision. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0115] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An optical noise suppressor, characterized in that: include: A substrate, the substrate comprising a bottom silicon layer, a middle oxide layer and a top silicon layer stacked from bottom to top, the substrate being provided with an air-avoiding space vertically penetrating the substrate, the air-avoiding space located in the top silicon layer region being provided with a grating structure and a cantilever beam structure, the grating structure being connected to the substrate via the cantilever beam structure; A piezoelectric driving structure is located above the cantilever beam structure, and the piezoelectric driving structure includes a bottom electrode metal layer, a piezoelectric film layer and a top electrode metal layer stacked from bottom to top; A top cover is located above the base and bonded to the base, a reflective layer is provided on the lower surface of the top cover, and the projection of the reflective layer on the base covers the grating structure, wherein after the piezoelectric drive structure applies a voltage, the cantilever beam structure can be driven to deform, thereby changing the distance between the grating structure and the top cover.

2. The optical noise suppressor according to claim 1, characterized in that: The piezoelectric driving structure also extends to above the top silicon layer, and a bottom electrode lead-out electrode and a top electrode lead-out electrode are arranged in the piezoelectric driving structure located above the top silicon layer, wherein the bottom electrode lead-out electrode is electrically connected to the bottom electrode metal layer, and the top electrode lead-out electrode is electrically connected to the top electrode metal layer.

3. The optical noise suppressor according to claim 2, characterized in that: The cross-sectional area of ​​the top cover is smaller than the cross-sectional area of ​​the substrate, and the top cover does not cover the bottom electrode lead-out electrode and the top electrode lead-out electrode.

4. The optical noise suppressor according to claim 1, characterized in that: A first bonding metal layer connected to the substrate is arranged above the substrate, and a second bonding metal layer connected to the top cover is arranged on the lower side of the top cover, wherein the first bonding metal layer is bonded to the second bonding metal layer so that the substrate is bonded to the top cover.

5. The optical noise suppressor according to claim 1, characterized in that: The distance between the grating structure and the reflective layer ranges from 0.5 to 4 um.

6. A method for manufacturing an optical noise suppressor, characterized in that: The following steps are involved: Providing a substrate, the substrate comprising a bottom silicon layer, an intermediate oxide layer and a top silicon layer stacked from bottom to top, forming a piezoelectric driving structure on the substrate, the piezoelectric driving structure comprising a bottom electrode metal layer, a piezoelectric film layer and a top electrode metal layer stacked from bottom to top; Etching the top silicon layer to form a grating structure and a cantilever beam structure in the top silicon layer, wherein the grating structure is connected to the top silicon layer through the cantilever beam structure, wherein the piezoelectric drive structure is located above the cantilever beam structure, and etching the bottom silicon layer and the middle oxide layer to form a back cavity, wherein the back cavity exposes the grating structure and the cantilever beam structure; A top cover is provided, a reflective layer is formed on the lower surface of the top cover, and the top cover is bonded to the substrate, wherein the projection of the reflective layer on the substrate covers the grating structure, wherein after the voltage is applied to the piezoelectric drive structure, the cantilever beam structure can be driven to deform, thereby changing the distance between the grating structure and the top cover.

7. The method for manufacturing an optical noise suppressor according to claim 6, characterized in that: The piezoelectric driving structure also extends to above the top silicon layer. After the piezoelectric driving structure is formed, it also includes the step of forming a bottom electrode lead-out electrode and a top electrode lead-out electrode in the piezoelectric driving structure located above the top silicon layer, wherein the bottom electrode lead-out electrode is electrically connected to the bottom electrode metal layer, and the top electrode lead-out electrode is electrically connected to the top electrode metal layer.

8. The method for manufacturing an optical noise suppressor according to claim 7, characterized in that: The cross-sectional area of ​​the top cover is smaller than the cross-sectional area of ​​the substrate, and the top cover does not cover the bottom electrode lead-out electrode and the top electrode lead-out electrode.

9. The method for manufacturing an optical noise suppressor according to claim 6, characterized in that: A first bonding metal layer connected to the substrate is formed above the substrate, and a second bonding metal layer connected to the top cover is formed on the lower side of the top cover, wherein the first bonding metal layer is bonded to the second bonding metal layer so that the substrate is bonded to the top cover.

10. An application of an optical noise suppressor, characterized in that: The following steps are involved: Building a test platform, the test platform comprising a laser, a beam splitter, a diamond, a balanced detector, a signal generator, and an optical noise suppressor as described in any one of claims 1 to 5; The laser is emitted by the laser, and the laser is divided into detection light and reference light by the beam splitter, wherein the detection light is irradiated to the diamond to generate a fluorescence signal, and the fluorescence signal is received by the first port of the balanced detector. The signal generator controls the change of the distance between the grating structure and the reflective layer of the optical noise suppressor so that the reference light is irradiated to the optical noise suppressor to generate a periodic diffraction signal, and the diffraction signal is received by the second port of the balanced detector. When the fluorescence signal and the diffraction signal are at the same order of magnitude, differential common mode suppression is performed.

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