Optical noise suppressor, manufacturing method and application

Abstract

The application provides an optical noise suppressor, a manufacturing method and an application, and the optical noise suppressor comprises a substrate, a piezoelectric driving structure and a top cover, the substrate is provided with a vertical through-space in the substrate, the vertical through-space is 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 the piezoelectric driving structure 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 bonded and connected above the substrate, the lower surface of the top cover is provided with a reflection layer, and the projection of the reflection layer on the substrate covers the grating structure, wherein the cantilever beam structure can be deformed after a voltage is applied to the piezoelectric driving structure, and then the distance between the grating structure and the top cover is changed. In the application, the distance between the grating structure and the reflection layer can be accurately controlled through voltage driving, the reference light intensity can be controlled and monitored in real time, and the application has the advantages of full automation and high precision.

Description

Technical Field

[0001] This invention belongs to the field of magnetic detection technology and relates to an optical noise suppressor, its manufacturing method, and its application. Background Technology

[0002] With the rapid development of laser technology, lasers have found wide applications in fields such as quantum optics, defense technology, and precision measurement. In scientific research involving high-precision measurements, operating lasers can couple mechanical vibration noise and thermal noise, causing light field fluctuations to become background noise and limiting the sensitivity of the measurement device. A common approach is to construct a closed-loop control for the laser drive current; however, the current source itself has limited control accuracy, and noise caused by temperature drift cannot be eliminated.

[0003] Noise in a 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 caused by optical field fluctuations due to unstable laser output power, which directly affects the detected fluorescence signal in the time domain. Studies have found that laser noise accounts for 0.1% to 1%, while the background noise is 0.001%. Therefore, for NV color center magnetic detection systems, laser noise is one of the main noises in NV color center magnetic sensing. There are many methods to reduce laser noise through common-mode suppression. For example, a beam splitter can be used to split the laser into a spatial reference beam and a probe beam. Two identical photodetectors are used for sampling for 1 second, and the ratio of the average values ​​of the two signals is obtained. By adjusting the light diffuser and the amplification factor of the reference photodetector based on software, the mean and variance of the two signals are kept consistent before differential analysis. Another study has improved the magnetic detection sensitivity by 10 times by splitting the laser to excite two diamond fluorescence beams, coupling them into a balanced detector with optical fiber, and adjusting the coupling efficiency to achieve numerical equality before differential analysis. However, these common-mode suppression methods, whether it is differential analysis of the spatial light or adjustment of the coupling efficiency, all require manual adjustment of optical components and are not compatible with microfabrication technology.

[0004] Therefore, how to provide an optical noise suppressor, its fabrication method, and its application to achieve automated control of the reference light and compatibility with microfabrication technology has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an optical noise suppressor, a manufacturing method and an application, to solve the problems of low modulation accuracy of manually modulated reference light intensity and incompatibility with microfabrication technology in the prior art.

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

[0007] The substrate includes a bottom silicon layer, an intermediate oxide layer and a top silicon layer stacked from bottom to top. A vertically penetrating clearance space is provided in the substrate. A grating structure and a cantilever beam structure are provided in the clearance space located in the region of the top silicon layer. The grating structure is connected to the substrate through the cantilever beam structure.

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

[0009] A top cover is located above the substrate and bonded to the substrate. The lower surface of the top cover is provided with a reflective layer. The projection of the reflective layer on the substrate covers the grating structure. When a voltage is applied to the piezoelectric drive structure, it can cause the cantilever beam structure to deform, thereby changing the distance between the grating structure and the top cover.

[0010] Optionally, the piezoelectric drive structure further extends above the top silicon layer, and a bottom electrode lead-out electrode and a top electrode lead-out electrode are provided in the piezoelectric drive 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, 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.

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

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

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

[0015] A substrate is provided, the substrate comprising a bottom silicon layer, an intermediate oxide layer and a top silicon layer stacked from bottom to top, and a piezoelectric driving structure is formed on the substrate, the piezoelectric driving structure comprising a bottom electrode metal layer, a piezoelectric thin film layer and a top electrode metal layer stacked from bottom to top;

[0016] The top silicon layer is etched to form a grating structure and a cantilever beam structure in the top silicon layer. The grating structure is connected to the top silicon layer through the cantilever beam structure. The piezoelectric drive structure is located above the cantilever beam structure. The bottom silicon layer and the intermediate oxide layer are etched to form a back cavity, which exposes the grating structure and the cantilever beam structure.

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

[0018] Optionally, the piezoelectric driving structure further extends above the top silicon layer. After forming the piezoelectric driving structure, the method further includes 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, 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.

[0020] Optionally, a first bonding metal layer connected to the substrate is formed on the upper surface of the substrate, and a second bonding metal layer connecting the top cover is formed on the lower side of the top cover, wherein the first bonding metal layer and the second bonding metal layer are bonded together to bond the substrate to the top cover.

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

[0022] A test platform is constructed, which includes a laser, a beam splitter, a diamond detector, a balanced detector, a signal generator, and any of the above-mentioned optical noise suppressors.

[0023] The laser emits a laser beam, which is split into a probe beam and a reference beam by the beam splitter. The probe beam illuminates the diamond to generate a fluorescence signal, which is received by the first port of the balanced detector. The signal generator controls the distance between the grating structure of the optical noise suppressor and the reflective layer to change, so that the reference beam illuminates the optical noise suppressor to generate a periodic diffraction signal. The diffraction signal is received by the second port of the balanced detector. Differential common-mode suppression is performed when the fluorescence signal and the diffraction signal are on the same order of magnitude.

[0024] As described above, the optical noise suppressor, manufacturing method, and application of the present invention can precisely control the spacing between the grating structure and the reflective layer through voltage driving, and can regulate and monitor the reference light intensity in real time, with the advantages of full automation and high precision. Attached Figure Description

[0025] Figure 1 The diagram shown is a cross-sectional schematic of the optical noise suppressor according to Embodiment 1 of the present invention.

[0026] Figure 2 The image shown is a top view of the first bonding metal layer disposed on the substrate in Embodiment 1 of the present invention.

[0027] Figure 3 The image shown is a bottom view of the top cover in Embodiment 1 of the present invention.

[0028] Figure 4 The diagram shows the optical interference principle of the optical noise suppressor in Embodiment 1 of the present invention.

[0029] Figure 5 The diagram shows the variation of the intensity of the positive first-order diffraction spot with the spacing in Embodiment 1 of the present invention.

[0030] Figure 6 The diagram shows the displacement change of the grating structure after applying voltage to the piezoelectric drive structure in Embodiment 1 of the present invention.

[0031] Figure 7 The diagram shows the process flow of the optical noise suppressor fabrication method according to Embodiment 2 of the present invention.

[0032] Figure 8 The diagram shown is a schematic of a piezoelectric drive structure formed on the top silicon layer in Embodiment 2 of the present invention.

[0033] Figure 9 The diagram shows a grating structure and a cantilever beam structure formed by etching the top silicon layer in Embodiment 2 of the present invention.

[0034] Figure 10 The diagram shows a top cover provided in Embodiment 2 of the present invention and the top cover bonded to the substrate.

[0035] Figure 11 The diagram shown is a schematic diagram of the test platform according to Embodiment 3 of the present invention.

[0036] Component designation explanation

[0037] 1. Base

[0038] 100 top silicon layers

[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 thin 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 layers

[0054] 701 Intermediate Oxide Layer

[0055] 702 bottom silicon layer

[0056] 8. Reflective layer

[0057] 9 Second bonding metal layer

[0058] 10 Oxide layer

[0059] 11 Reference Light

[0060] 12 Lasers

[0061] 13 beam splitters

[0062] 14. Diamond

[0063] 15 Balance Detector

[0064] 16 Signal Generator

[0065] 17. Optical noise suppressor

[0066] 18 Filters

[0067] 19 Focusing Lens

[0068] 20 Reflectors

[0069] Steps S1 to S3 Detailed Implementation

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

[0071] Please see Figures 1 to 11 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0072] Example 1

[0073] This embodiment provides an optical noise suppressor; please refer to [link / reference]. Figure 1 The image shows a cross-sectional schematic of the optical noise suppressor, including a substrate 1, a piezoelectric drive structure 4, and a top cover 7. The substrate 1 comprises a bottom silicon layer 102, an intermediate oxide layer 101, and a top silicon layer 100 stacked from bottom to top. A vertically penetrating clearance space is provided in the substrate 1. A grating structure 2 and a cantilever beam structure 3 are disposed in the clearance space located in the region of the top silicon layer 100. The grating structure 2 is connected to the substrate 1 via the cantilever beam structure 3. The piezoelectric drive structure 4 is located in the cantilever beam structure 7. Above the cantilever beam structure 3, the piezoelectric drive structure 4 includes a bottom electrode metal layer 400, a piezoelectric thin 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 the lower surface of the top cover 7 is provided with a reflective layer 8. The projection of the reflective layer 8 on the substrate 1 covers the grating structure 2. After a voltage is applied to the piezoelectric drive 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 substrate 1 is 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 provided in the intermediate oxide layer 101 and the bottom silicon layer 102. 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, the upper surface of the top silicon layer 100 is provided with an insulating layer 5 to insulate the piezoelectric drive structure 4 from the substrate 1. The piezoelectric drive structure 4 extends from the cantilever beam structure 3 region to the top silicon layer 100 region. The piezoelectric drive structure 4 located in the cantilever beam structure 3 region is used to provide power for the deformation of the cantilever beam structure 3. The piezoelectric drive structure 4 located in the top silicon layer 100 region is used for electrode lead-out. The piezoelectric drive structure 4 located in the top silicon layer 100 region 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 disposed on the top silicon layer 100. The first bonding metal layer 6 includes metal materials such as aluminum, germanium, gold, and tin. A bottom electrode metal layer 400, a piezoelectric thin film layer 401, and a top electrode metal layer 402 are disposed 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] For example, please refer to Figure 2 The image shows a top view of the base. The cantilever beam structure 3 has a six-axis structure and is evenly distributed around the periphery of the grating structure 2, so that the cantilever beam structure 3 can uniformly drive the grating structure 2 to move when it deforms. Furthermore, the axes of the cantilever beam structure 3 are separated by gaps, reducing air damping during the sensing process and thus reducing noise and improving the overall signal-to-noise ratio. Of course, in other examples, the cantilever beam structure 3 can also be configured as a two-axis, three-axis, four-axis, five-axis, seven-axis, or eight-axis structure, etc., and is not limited to this embodiment.

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

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

[0080] For example, please refer to Figure 3The image shows a bottom view of the top cover. The cross-sectional area of ​​the top cover 7 is smaller than that of the base 1. After the top cover 7 is bonded to the base 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 drive structure 4 and external devices.

[0081] For example, please refer to Figure 4 The diagram shows the optical interference principle of an optical noise suppressor. When reference light 11 is incident perpendicularly, part of the light is reflected and diffracted at the grating structure 2, while the other part passes through the grating structure 2, reaches the reflective layer 8, is reflected, and then diffracts again at the grating structure 2. This results in two sets of diffracted light with a phase difference interfering constructively or destructively, producing multi-order interference spots (e.g., 0th order, ±1st order, ±2nd order, etc.). The light intensity of each order spot can be derived based on Fraunhofer diffraction theory. Taking the ±1st diffraction order as an example, the light intensity of the ±1st diffraction order is:

[0082]

[0083] Among them, I in Let 11 be the intensity of the reference light, λ be the incident wavelength, and d be the distance between the grating structure 2 and the reflective layer 8. Analysis shows that adjusting the distance d between the grating structure 2 and the reflective layer 8 can adjust the intensity of the ±1st order diffraction light, allowing for high-precision adjustment of the sinusoidal intensity amplitude. In other words, by adjusting the distance d between the grating structure 2 and the reflective layer 8, a positive first-order light intensity with brightness variations can be obtained. The intensity control range is designed based on the intensity value of the signal to be measured, ensuring that the order of magnitude of the first-order diffraction intensity amplitude is on the same order of magnitude as the intensity of the signal to be measured.

[0084] As an example, applying voltage to the piezoelectric drive structure 4 causes the cantilever beam structure 3 to deform, thereby moving the grating structure 2 and 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 of the positive first-order diffraction light intensity from the minimum light intensity to the maximum light intensity is defined as the minimum braking distance. The distance range by which the piezoelectric drive structure 4 moves the grating structure 2 is greater than the minimum braking distance, so as to ensure that the periodically changing light intensity amplitude is generated when the piezoelectric drive structure 4 moves the grating structure 2.

[0086] As an example, in this embodiment, the grating structure 2 has a duty cycle of 0.5, a period of 4 μm, and a thickness of 5 μm. Simulation results show a schematic diagram illustrating the change in the intensity of the positive first-order diffraction spot as a function of the spacing. Figure 5As shown, by scanning the spacing values ​​based on maximizing the grating diffraction efficiency, the periodically varying first-order diffraction intensity amplitude is obtained, with a minimum braking distance of 135 nm; Figure 6 As shown, when a voltage of 0-80V is applied to the piezoelectric driving structure 4, the quasi-static displacement of the grating structure 2 is 0-250nm and has high linearity. That is, the structure designed in this application can precisely control the spacing between the grating structure and the reflective layer through voltage driving, and can adjust and monitor the reference light intensity in real time. Compared with the traditional method of manually modulating the reference light intensity, the optical noise suppressor of this embodiment has the advantages of full automation and high precision through voltage driving.

[0087] As described above, the optical noise suppressor in this embodiment can precisely control the spacing between the grating structure and the reflective layer through voltage drive, and can regulate and monitor the reference light intensity in real time, with the advantages of full automation and high precision.

[0088] Example 2

[0089] This embodiment provides a method for fabricating an optical noise suppressor, used to fabricate the optical noise suppressor described in Embodiment 1. Please refer to [link / reference needed]. Figure 7 The diagram shows the process flow of this manufacturing method, including the following steps:

[0090] S1: Provide a substrate, the substrate comprising a bottom silicon layer, an intermediate oxide layer and a top silicon layer stacked from bottom to top, and form a piezoelectric drive structure on the substrate, the piezoelectric drive structure comprising a bottom electrode metal layer, a piezoelectric thin film layer and a top electrode metal layer stacked from bottom to top;

[0091] S2: Etch the top silicon layer to form a grating structure and a cantilever beam structure in the top silicon layer. The grating structure is connected to the top silicon layer through the cantilever beam structure. The piezoelectric drive structure is located above the cantilever beam structure. Etch the bottom silicon layer and the intermediate oxide layer to form a back cavity. 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, and the projection of the reflective layer on the substrate covers the grating structure. When a voltage is applied to the piezoelectric drive structure, it can cause the cantilever beam structure to deform, thereby changing the distance between the grating structure and the top cover.

[0093] First, please refer to Figure 8Step S1: Provide a substrate 1, the substrate 1 including 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 drive structure 4 on the substrate 1, the piezoelectric drive structure 4 including a bottom electrode metal layer 400, a piezoelectric thin film layer 401 and a top electrode metal layer 402 stacked from bottom to top.

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

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

[0096] As an example, after forming the piezoelectric drive structure 4, the process further includes forming a bottom electrode lead-out electrode 403 and a top electrode lead-out electrode 404 using a deposition process and a patterning process. 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, the first bonding metal layer 6 is formed at a preset position of the top electrode metal layer 402 in the bonding region using a deposition process and a patterning process. The material of the first bonding metal layer 6 includes metal materials such as aluminum, germanium, gold, and tin.

[0098] Next, please refer to Figure 9 Step S2 is executed: the top silicon layer 100 is etched to form 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. The piezoelectric drive structure 4 is located above the cantilever beam structure 3. The bottom silicon layer 102 and the intermediate oxide layer 101 are etched to form a back cavity 103. The back cavity 103 exposes the grating structure 2 and the cantilever beam structure 3.

[0099] As an example, the insulating layer 5 is patterned using photolithography, 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. (See also...) Figure 2The cantilever beam structure 3 has a six-axis structure and is evenly distributed around the periphery of the grating structure 2, so that the grating structure 2 moves evenly when the cantilever beam structure 3 deforms. Furthermore, the axes of the cantilever beam structure 3 are spaced apart to reduce air damping during the sensing process, thereby reducing noise and improving the overall signal-to-noise ratio. Of course, in other examples, the cantilever beam structure 3 can also be configured as a two-axis, three-axis, four-axis, five-axis, seven-axis, or eight-axis structure, etc., and is not limited to this embodiment.

[0100] As an example, the back cavity 103 is formed in the intermediate oxide layer 101 and the bottom silicon layer 102 using an etching process. 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, please refer to Figure 10 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, and the projection of the reflective layer 8 on the substrate 1 covers the grating structure 2. When a voltage is applied to the piezoelectric drive 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.

[0102] As an example, the top cover 7 uses an SOI substrate and includes 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, the method further includes 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 using deposition and etching processes. The second bonding metal layer 9 corresponds to the position of the first bonding metal layer 6. A reflective layer 8 is formed using deposition and etching processes. The reflective layer 8 is a metal reflective layer.

[0104] For example, please refer to Figure 3 The cross-sectional area of ​​the top cover 7 is smaller than that 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 drive structure 4 and external devices.

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

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

[0107] Example 3

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

[0109] 1) such as Figure 11 As shown, a test platform is built, which 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 Embodiment 1.

[0110] 2) The laser 12 emits a laser beam, which is split into a probe beam and a reference beam by the beam splitter 13. The probe beam illuminates the diamond 14 to generate a fluorescence signal, which is received by the first port of the balanced detector 15. 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 beam illuminates the optical noise suppressor 17 to generate a periodic diffraction signal. The diffraction signal is received by the second port of the balanced detector 15. Differential common-mode suppression is performed when the fluorescence signal and the diffraction signal are on the same order of magnitude.

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

[0112] As an example, the diffraction signal is reflected by the mirror 20 and then received by the second port of the balanced detector 15.

[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. The voltage amplitude change of the positive first-order diffraction spot after photoelectric conversion is read 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 differential is performed. The reference light has an optical noise signal, and the probe 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 the measurement of magnetic fields on the pT scale and has great development potential in the fields of biomedicine, materials science, and energy detection.

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

[0115] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can 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 those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A light noise suppressor, characterized in that, include: The substrate includes a bottom silicon layer, an intermediate oxide layer and a top silicon layer stacked from bottom to top. A vertically penetrating clearance space is provided in the substrate. A grating structure and a cantilever beam structure are provided in the clearance space located in the region of the top silicon layer. The grating structure and the cantilever beam structure are formed based on the top silicon layer. The grating structure is connected to the substrate through the cantilever beam structure. A piezoelectric drive structure is located above the cantilever beam structure. The piezoelectric drive structure includes a bottom electrode metal layer, a piezoelectric thin film layer, and a top electrode metal layer stacked from bottom to top. A top cover is located above the substrate and bonded to the substrate. The lower surface of the top cover is provided with a reflective layer. The projection of the reflective layer on the substrate covers the grating structure. When a voltage is applied to the piezoelectric drive structure, it can cause the cantilever beam structure to deform, thereby changing the distance between the grating structure and the top cover to regulate the reference light intensity, thereby differentially suppressing laser noise in the probe light.

2. The optical noise suppressor according to claim 1, characterized in that: The piezoelectric drive structure extends above the top silicon layer. The piezoelectric drive structure located above the top silicon layer is provided with a bottom electrode lead-out electrode and a top electrode lead-out electrode. 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 that of the base, 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 disposed on the upper side of the substrate, and a second bonding metal layer connected to the top cover is disposed on the lower side of the top cover, wherein the first bonding metal layer and the second bonding metal layer are bonded together to bond the substrate and 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 μm.

6. A method for manufacturing an optical noise suppressor, used to manufacture the optical noise suppressor of claim 1, characterized in that, Includes the following steps: A substrate is provided, the substrate comprising a bottom silicon layer, an intermediate oxide layer and a top silicon layer stacked from bottom to top, and a piezoelectric driving structure is formed on the substrate, the piezoelectric driving structure comprising a bottom electrode metal layer, a piezoelectric thin film layer and a top electrode metal layer stacked from bottom to top; The top silicon layer is etched to form a grating structure and a cantilever beam structure in the top silicon layer. The grating structure is connected to the top silicon layer through the cantilever beam structure. The piezoelectric drive structure is located above the cantilever beam structure. The bottom silicon layer and the intermediate oxide layer are etched to form a back cavity, which exposes the grating structure and the cantilever beam structure. A top cover is provided, and a reflective layer is formed on the lower surface of the top cover. The top cover is bonded to the substrate. The projection of the reflective layer on the substrate covers the grating structure. When a voltage is applied to the piezoelectric drive structure, the cantilever beam structure can be deformed, 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 drive structure extends above the top silicon layer. After forming the piezoelectric drive structure, the method further includes forming a bottom electrode lead-out electrode and a top electrode lead-out electrode in the piezoelectric drive structure located above the top silicon layer. 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 that of the base, 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 on the upper surface of 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 and the second bonding metal layer are bonded together to bond the substrate to the top cover.

10. An application of an optical noise suppressor, characterized in that, Includes the following steps: A test platform is constructed, which includes a laser, a beam splitter, a diamond detector, a balanced detector, a signal generator, and an optical noise suppressor as described in any one of claims 1-5; The laser emits a laser beam, which is split into a probe beam and a reference beam by the beam splitter. The probe beam illuminates the diamond to generate a fluorescence signal, which is received by the first port of the balanced detector. The signal generator controls the distance between the grating structure of the optical noise suppressor and the reflective layer to change, so that the reference beam illuminates the optical noise suppressor to generate a periodic diffraction signal. The diffraction signal is received by the second port of the balanced detector. Differential common-mode suppression is performed when the fluorescence signal and the diffraction signal are on the same order of magnitude.

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