Integrated gradient magnetic field sensor based on cavity optical mechanical structure

Abstract

The invention discloses an integrated gradient magnetic field sensor based on a cavity optical mechanical structure, which comprises a cavity optical mechanical sensing unit array, an optical waveguide structure, a multi-channel optical power equalizer and a photoelectric detector array which are integrated on the same substrate, and is characterized in that the cavity optical mechanical sensing unit array comprises a photonic crystal microcavity and a mechanical sensitive structure; the mechanical sensitive structure comprises a cantilever beam and a mass block, a metal wire is arranged on the surface of the cantilever beam, the end of the metal wire is connected with a metal bonding pad and forms a current loop, the metal wire is sleeved with a supporting block, and under the action of an external magnetic field, the metal wire drives the mass block to generate mechanical displacement under the action of Lorentz force. And the displacement outputs light intensity change through optical mechanical strong coupling modulation. And the multi-channel optical power equally-dividing device is used for uniformly distributing the optical signals to the plurality of waveguide-magnetic field sensing units. And the waveguide-magnetic field sensor integrated unit is used for synchronously measuring the magnetic field intensity in spatial distribution and generating a gradient magnetic field distribution diagram by collecting output signals of each unit.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of micro-electro-mechanical system and optomechanical magnetic field sensing, and particularly relates to an integrated gradient magnetic field sensor based on a cavity optomechanical structure. BACKGROUND

[0002] The existing gradient magnetic field measurement technology generally has the problems of limited spatial resolution and insufficient integration. Traditional anisotropic magnetoresistance (AMR / GMR) and atomic spin (SERF) sensors rely on differential detection and need a millimeter-level baseline distance to calculate the magnetic field gradient, sacrificing the spatial resolution and being affected by thermal noise and environmental instability. Although superconducting quantum interference devices (SQUID) and diamond nitrogen vacancy (NV) color center technology have sub-millimeter resolution, the former is limited by low temperature and large size design, and the latter is difficult to miniaturize due to power consumption and fluorescence collection efficiency.

[0003] Micro-electro-mechanical system (MEMS) technology directly senses the magnetic field gradient through mechanical displacement, which is expected to break through these bottlenecks, but still faces challenges such as thermal drift caused by driving current, air damping reducing the quality factor of resonance, and material interface stress mismatch, affecting long-term stability and practical sensitivity. The cavity optomechanical sensor can significantly improve the signal readout sensitivity through strong coupling between the photonic crystal microcavity and mechanical vibration, and can directly convert the external magnetic field into mechanical displacement through Lorentz force driving, so as to realize high-sensitivity detection through optical resonance. However, the existing cavity optomechanical magnetic field sensor is mostly for single-point detection, and has not realized high integration and gradient measurement function.

[0004] Therefore, a cavity optomechanical magnetic field sensor array based on Lorentz force driving is needed to realize high spatial resolution, integration and low-power gradient magnetic field detection. SUMMARY

[0005] The purpose of the application is to solve the above problems and provide an integrated gradient magnetic field sensor based on a cavity optomechanical structure, which is driven by the Lorentz force generated under the action of an external magnetic field to cause displacement of a mechanical sensitive structure, and uses the optomechanical strong coupling effect to efficiently modulate the displacement into optical signal changes. Combined with an on-chip multi-channel optical power divider and a photodetector array, multi-point synchronous signal acquisition and differential operation can be realized to obtain a gradient magnetic field distribution map.

[0006] To solve the above technical problems, the technical scheme of the present application is: an integrated gradient magnetic field sensor based on a cavity optomechanical structure, comprising a cavity optomechanical sensing unit array, an optical waveguide structure, a multi-channel optical power divider and a photodetector array integrated on the same substrate, the cavity optomechanical sensing unit array comprises a photonic crystal microcavity and a mechanical sensitive structure, the mechanical sensitive structure comprises a cantilever beam and a mass block, the cantilever beam is provided with a metal wire on the surface, the end of the metal wire is connected with a metal pad, and a current loop is formed, a support block is sleeved on the metal wire, under the action of an external magnetic field, the metal wire is driven by the Lorentz force to make the mass block produce mechanical displacement, and the displacement is modulated by optomechanical strong coupling to output light intensity change; the optical waveguide structure is used for coupling and guiding input light to the multi-channel optical power divider, the multi-channel optical power divider is used for uniformly distributing optical signals to a plurality of waveguide-magnetic field sensing units; the photodetector array corresponds to the waveguide-magnetic field sensing units one by one, and is used for synchronously collecting multiple optical signals; a plurality of waveguide-magnetic field sensor integrated units are linearly arranged at a preset micron-level spacing, are used for synchronously measuring spatially distributed magnetic field intensity, and generate a gradient magnetic field distribution map through the output signals of each unit.

[0007] Preferably, the cavity optomechanical sensing unit array is linearly arranged at a preset micron-level spacing, is used for realizing synchronous collection of spatial multi-point magnetic field signals, and obtains a gradient magnetic field distribution through differential operation between adjacent units.

[0008] Preferably, the substrate is an SOI substrate, the SOI substrate is provided with a through hole at a preset position and is connected with the lower metal pad to form a current supply path, which is used for providing working current for the metal wire on the surface of the cantilever beam, so as to generate Lorentz force under the action of an external magnetic field to drive the mass block to move.

[0009] Preferably, the optical waveguide structure couples input laser to the photonic crystal microcavity to form optical resonance, under the action of an external magnetic field, the metal wire on the surface of the cantilever beam is driven by the Lorentz force to drive the mass block to produce mechanical displacement, the displacement modulates the resonance characteristics of the microcavity through the optomechanical coupling effect and causes the output light intensity to change; the output light is transmitted to the photodetector array through the waveguide, and the photodetector array detects the change of the light intensity, so as to realize quantitative measurement of the external magnetic field.

[0010] Preferably, the multi-channel optical power divider is an N-way equal division structure, wherein N is greater than or equal to 2, which is used for uniformly distributing input optical signals to each unit in the cavity optomechanical sensing unit array, so as to ensure synchronous excitation and detection of multi-point magnetic field signals.

[0011] Preferably, the optical waveguide structure is formed on the functional layer of the SOI substrate through a photolithography and etching process, and is coupled with the photonic crystal microcavity; the resonance signal of the photonic crystal microcavity is transmitted to the photodetector and the spectrum analysis module through the output waveguide, for synchronous demodulation of the output light intensity change and mechanical vibration characteristics.

[0012] Preferably, the mass is fixed on the functional layer of the SOI substrate through a cantilever beam to form a mechanical resonance structure; the length of the cantilever beam is 100-200 μm, and the width is 0.5-2 μm.

[0013] Preferably, the photodetector array is used to convert the output optical signal into an electrical signal, to detect the change of the output light intensity in real time, and to amplify, filter and demodulate the signal, so as to inverse the external magnetic field and its gradient; the photodetector array and the cavity optomechanical sensing unit array maintain a consistent spatial interval, so as to ensure the spatial correspondence and synchronous acquisition accuracy of the multi-channel signal.

[0014] Preferably, the sensor adopts the SOI wafer as a substrate in the manufacturing process, the thicknesses of the top silicon, the buried oxygen layer and the base silicon are set according to the design requirements of the device, and the optical waveguide, the photonic crystal microcavity and the mechanical sensitive structure are formed on the functional layer through a micro-nano processing technology.

[0015] Preferably, the signal amplification, filtering and demodulation are used for normalized calibration and differential operation of the photoelectric output signal of the cavity optomechanical sensing unit array, and a two-dimensional gradient magnetic field distribution map is generated, so as to realize the magnetic field imaging with high spatial resolution.

[0016] The beneficial effects of the present application are:

[0017] 1. The integrated gradient magnetic field sensor based on the cavity optomechanical structure adopts a multi-unit array layout and an optical power divider, and integrates the cavity optomechanical sensing unit array with a micron-level interval on the same chip platform. By simultaneously acquiring the magnetic field intensity of each unit position and performing differential operation, the magnetic field gradient distribution can be directly obtained, and the gradient measurement with high spatial resolution is realized.

[0018] 2. The current supply mode based on the through hole and the pad is arranged in the neighborhood of the root of the cantilever beam and constitutes a local independent driving loop through the lower pad, which is used for providing working current for the metal wire of the cantilever beam to generate the Lorentz force. This scheme avoids the cross interference between the surface metal wire and the optical waveguide and the photonic crystal microcavity, and ensures the stability of the photoelectric performance under the array integration.

[0019] 3. The present application utilizes the mechanical resonance amplification effect and the optomechanical strong coupling mechanism, so that the sensor can modulate the mechanical disturbance caused by the external magnetic field between adjacent units into the change of the optical signal, and realize the high-sensitivity response to the weak gradient magnetic field change.

[0020] 4、The application has the characteristics of high integration, and integrates the optical waveguide, the photonic crystal microcavity, the mechanical sensitive structure, the multi-channel optical power divider and the photodetector array on a single chip platform, effectively reduces the device volume and simplifies the system structure, thereby significantly improving the overall compactness and expandability, and is suitable for miniaturization and portable application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is the overall structure schematic diagram of an integrated gradient magnetic field sensor based on a cavity optomechanical structure according to the application;

[0022] Figure 2 is a single magnetic field sensor amplification diagram according to the application;

[0023] Figure 3 is a structure schematic diagram of a photonic crystal microcavity according to the application;

[0024] Figure 4 is a photodetector amplification diagram according to the application;

[0025] Figure 5 is an optical waveguide structure schematic diagram according to the application;

[0026] Figure 6 is an arrayed sensor metal wiring schematic diagram according to the application.

[0027] Mark explanation: 1, cavity optomechanical sensing unit array; 2, optical waveguide structure; 3, multi-channel optical power divider; 4, photodetector array; 11, photonic crystal microcavity; 12, mechanical sensitive structure; 121, cantilever beam; 122, mass block; 123, metal wire; 124, metal pad; 125, support block. DETAILED DESCRIPTION

[0028] The application will be further described below in combination with the drawings and specific embodiments:

[0029] As Figures 1 to 6As shown, the application provides an integrated gradient magnetic field sensor based on cavity optomechanical structure, which comprises a cavity optomechanical sensor unit array 1, an optical waveguide structure 2, a multi-channel optical power divider 3 and a photodetector array 4 integrated on the same substrate. The cavity optomechanical sensor unit array 1 comprises a photonic crystal microcavity 11 and a mechanical sensitive structure 12. The mechanical sensitive structure 12 comprises a cantilever beam 121 and a mass block 122. The surface of the cantilever beam 121 is provided with a metal wire 123. The end of the metal wire 123 is connected with a metal pad 124, and forms a current loop. The metal wire 123 is sleeved with a support block 125. Under the action of an external magnetic field, the metal wire 123 drives the mass block 122 to produce mechanical displacement under the action of Lorentz force. The displacement is modulated by strong optomechanical coupling to output the change of light intensity. The optical waveguide structure 2 is used for coupling and guiding the input light to the multi-channel optical power divider 3. The multi-channel optical power divider 3 is used for uniformly distributing the optical signal to a plurality of waveguide-magnetic field sensor units. The photodetector array 4 corresponds to the waveguide-magnetic field sensor unit one by one, and is used for synchronously collecting multiple optical signals. A plurality of waveguide-magnetic field sensor integration units are linearly arranged at a preset micron-level spacing, and are used for synchronously measuring the spatially distributed magnetic field intensity, and generating a gradient magnetic field distribution map through the output signals of each unit.

[0030] In the embodiment, the substrate is an SOI insulator silicon substrate, which comprises a top silicon layer, a buried oxygen layer and a silicon substrate arranged in sequence from top to bottom. The top silicon layer is a functional layer. The optical waveguide structure is formed on the functional layer by photolithography and dry etching process. The optical waveguide structure 2 comprises a straight waveguide and a tapered waveguide connected in sequence. The input end is composed of the straight waveguide and the tapered waveguide in sequence, which is used for efficiently coupling the external laser and realizing mode matching. Mode matching refers to gradually transitioning the external laser to the fundamental mode distribution of the on-chip waveguide through the gradual design of the tapered waveguide, so as to realize matching in the spatial field type and the effective refractive index, and reduce the coupling loss. Such design can significantly improve the coupling efficiency of the input light and the waveguide mode field. The optical signal then enters the multi-channel optical power divider 3, which uniformly distributes the input light to the cavity optomechanical sensor unit array 1. The cavity optomechanical sensor unit array 1 comprises a plurality of sensor units, each of which is composed of a photonic crystal microcavity 11 and a mechanical sensitive structure 12. The photonic crystal microcavity 11 is used for forming high-Q optical resonance, and realizes strong optomechanical coupling with the mechanical sensitive structure 12. The output end is composed of the tapered waveguide and the straight waveguide, which realizes mode conversion of the optical signal and efficiently transmits the optical signal to the photodetector array 4.

[0031] The photonic crystal microcavity 11 is a mature device structure, and the optomechanical strong coupling is realized by the interaction of the photonic crystal microcavity 11 and the mechanical sensitive structure 12. When the cantilever beam 121 is driven to produce a slight displacement under the action of the external magnetic field, the mass block 122 drives the disturbance of the photonic crystal microcavity boundary, thereby modulating the resonance condition of the microcavity and causing the output light intensity to change.

[0032] The waveguide-magnetic field sensing unit refers to an integrated detection unit composed of the optical waveguide structure 2, the photonic crystal microcavity 11, the mechanical sensitive structure 12, and the metal wire 123 and the metal pad 124. The optical waveguide structure 2 is responsible for coupling and transmitting the input light signal to the photonic crystal microcavity. The mechanical sensitive structure 12 is driven to produce displacement by the Lorentz force under the action of the external magnetic field, thereby modulating the resonance characteristics of the microcavity and causing the output light intensity to change, so as to realize single-point magnetic field signal detection. After the array arrangement of a plurality of units, it can be used for synchronous acquisition of multi-point magnetic field and gradient operation. The support block 125 is provided with a support block through hole, and the metal wire 123 is arranged in the support block through hole.

[0033] The cavity optomechanical sensing unit array 1 is linearly arranged at a preset micron-level pitch, for realizing synchronous acquisition of spatial multi-point magnetic field signals, and obtaining gradient magnetic field distribution through differential operation between adjacent units. The adjacent units refer to two adjacent waveguide-magnetic field sensing units linearly arranged at a pitch in the cavity optomechanical sensing unit array.

[0034] The SOI (Silicon on Insulator) substrate is referred to as SOI substrate. The SOI substrate is provided with a through hole at a preset position and is connected with the lower metal pad 124 to form a current supply path for providing working current for the metal wire 123 on the surface of the cantilever beam, so as to generate Lorentz force under the action of the external magnetic field to drive the mass block 122 to move.

[0035] The optical waveguide structure 2 couples the input laser to the photonic crystal microcavity 11 to form an optical resonance. The metal wire 123 on the surface of the cantilever beam 121 is driven by the Lorentz force to drive the mass block 122 to produce mechanical displacement under the action of the external magnetic field. The displacement modulates the resonance characteristics of the microcavity through the optomechanical coupling effect and causes the output light intensity to change. The output light is transmitted to the photodetector array 4 through the waveguide and is converted into an electrical signal in real time. The photodetector array 4 detects the change of the light intensity to realize quantitative measurement of the external magnetic field. After subsequent processing, the gradient magnetic field distribution map can be obtained.

[0036] The external laser first realizes mode matching and efficient coupling through the tapered waveguide, then enters the on-chip straight waveguide, and is uniformly distributed to each sensing unit through the multi-channel optical power divider 3. In this embodiment, the sensing unit refers to the waveguide-magnetic field sensor integrated unit.

[0037] The multi-channel optical power divider 3 is an existing N-way equal division structure, where N≥2, for uniformly distributing the input optical signal to each unit in the array of cavity optomechanical sensing units, to ensure synchronous excitation and detection of the multi-point magnetic field signal.

[0038] The optical waveguide structure 2 is formed on the functional layer of the SOI substrate by photolithography and etching process, and is coupled with the photonic crystal microcavity 11. The resonance signal of the photonic crystal microcavity is transmitted to the photodetector through the output waveguide, for synchronous demodulation of the output light intensity change and mechanical vibration characteristics.

[0039] The mass 122 is fixed on the SOI substrate functional layer through the cantilever beam 121 to form a mechanical resonance structure. The cantilever beam 121 has a length of 100-200 μm and a width of 0.5-2 μm.

[0040] The photodetector array 4 includes a plurality of photodetectors, and is used for converting the output optical signal into an electrical signal, detecting the change of the output light intensity in real time, and amplifying, filtering and demodulating the signal to invert the external magnetic field and its gradient. The photodetector array 4 maintains the same spatial interval as the array of cavity optomechanical sensing units 1, to ensure the spatial correspondence and synchronous acquisition accuracy of the multi-channel signal.

[0041] In the manufacturing process, the SOI wafer is used as the substrate, the thicknesses of the top silicon, buried oxygen layer and base silicon are set according to the design requirements of the device, and the optical waveguide, photonic crystal microcavity and mechanical sensitive structure are formed on the functional layer by micro-nano processing technology.

[0042] The amplification, filtering and demodulation of the signal are used for normalizing calibration and differential operation of the photoelectric output signal of the array of cavity optomechanical sensing units, and generate a two-dimensional gradient magnetic field distribution map, to realize high spatial resolution magnetic field imaging.

[0043] To realize arraying and high spatial resolution measurement, a plurality of cavity optomechanical sensing units are linearly arranged with a preset micron-level interval to form the array of cavity optomechanical sensing units 1. The input light is uniformly distributed to each unit by the on-chip optical power divider, to form multi-point synchronous excitation. The output optical signal of each unit is transmitted to the photodetector array 4 through the waveguide, and the photodetector array 4 corresponds to each unit in the array of cavity optomechanical sensing units 1, to ensure the correspondence of the spatial position and signal acquisition. The output of adjacent units is subjected to differential operation, to obtain the high spatial resolution gradient magnetic field distribution of the target region, and realize high spatial resolution measurement. The overall structure is shown in Figure 1

[0044] ​In the current supply mode, to avoid the surface metal trace from crossing and interfering with the optical device, the application arranges a through hole at the root of the cantilever beam, which is connected with the metal interconnection line of the substrate layer to form a local independent current path. The through holes of multiple units are interconnected by metal traces on the substrate layer and finally converge to the pad to realize unified power supply. The structure is schematically shown in Figure 4 The working current is provided for the cantilever beam metal wire to generate the Lorentz force, ensuring the stability of the optical performance and the feasibility of array integration.

[0045] In the manufacturing process, an SOI wafer is selected as the substrate, the thicknesses of the top layer silicon, the buried oxygen layer and the substrate silicon are set according to the design requirements of the device, and the micro-nano processing technology such as electron beam lithography and dry etching is used to prepare the photonic crystal microcavity, the mechanical sensitive structure and the optical waveguide on the functional layer. A multi-channel optical power divider is processed at the input end, and a photodetector array is integrated at the output end. A through hole is prepared in the vicinity of the root of the cantilever beam, and the unified power supply for the entire magnetic field sensor array is completed through the current supply mode as described above.

[0046] To ensure the gradient measurement accuracy, the zero point output and the sensitivity of each sensing unit can be normalized and calibrated in a calibration environment with known magnetic field distribution. The system can simultaneously acquire all unit signals under single light source input and quickly generate a two-dimensional gradient magnetic field distribution map.

[0047] Through the above design, the application deeply combines the Lorentz force driving with the cavity-optomechanical strong coupling mechanism, breaks through the limitations of traditional single-point cavity-optomechanical sensors, realizes on-chip array, high spatial resolution and low power consumption of the gradient magnetic field imaging, and is suitable for precise magnetic field detection, inertial-magnetic composite navigation, geophysical exploration and biomagnetic measurement fields.

[0048] Those skilled in the art will appreciate that the embodiments described herein are intended to help the reader understand the principles of the application and should be understood as not limiting the scope of protection of the application to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations according to the technical inspiration disclosed in the application without departing from the essence of the application, and these modifications and combinations are still within the scope of protection of the application.

Claims

1. An integrated gradient magnetic field sensor based on a cavity optomechanical structure, characterized in that: The system includes a cavity optomechanical sensing unit array (1), an optical waveguide structure (2), a multi-channel optical power divider (3), and a photodetector array (4) integrated on the same substrate. The cavity optomechanical sensing unit array (1) includes a photonic crystal microcavity (11) and a mechanically sensitive structure (12). The mechanically sensitive structure (12) includes a cantilever beam (121) and a mass block (122). The surface of the cantilever beam (121) is provided with a metal wire (123). The end of the metal wire (123) is connected to a metal pad (124) and forms a current loop. A support block (125) is sleeved on the metal wire (123). Under the action of an external magnetic field, the metal wire (123) Driven by the Lorentz force, the mass block (122) generates a mechanical displacement, which is modulated by optomechanical strong coupling to change the output light intensity; the optical waveguide structure (2) is used to couple and guide the input light to the multi-channel optical power equalizer (3), which is used to evenly distribute the optical signal to multiple waveguide-magnetic field sensing units; the photodetector array (4) corresponds one-to-one with the waveguide-magnetic field sensing units and is used to synchronously acquire multiple optical signals; multiple waveguide-magnetic field sensor integrated units are linearly arranged with a preset micron-level spacing to synchronously measure the spatially distributed magnetic field intensity and generate a gradient magnetic field distribution map by acquiring the output signals of each unit.

2. The integrated gradient magnetic field sensor based on a cavity optomechanical structure according to claim 1, characterized in that: The cavity optomechanical sensing unit array (1) is linearly arranged according to a preset micron-level spacing to realize the synchronous acquisition of magnetic field signals at multiple points in space, and to obtain the gradient magnetic field distribution through differential operation between adjacent units.

3. The integrated gradient magnetic field sensor based on a cavity optomechanical structure according to claim 1, characterized in that: The substrate is an SOI substrate. The SOI substrate has through holes at preset positions and is connected to the metal pads (124) below to form a current supply path, which is used to provide working current to the metal wires on the surface of the cantilever beam, thereby generating Lorentz force under the action of an external magnetic field to drive the mass block to move.

4. The integrated gradient magnetic field sensor based on a cavity optomechanical structure according to claim 1, characterized in that: The optical waveguide structure (2) couples the input laser to the photonic crystal microcavity (11) to form an optical resonance. Under the action of an external magnetic field, the metal wires on the surface of the cantilever beam (121) are driven by the Lorentz force to cause the mass block (122) to generate mechanical displacement. The displacement modulates the resonance characteristics of the microcavity through the optomechanical coupling effect and causes a change in the output light intensity. The output light is transmitted to the photodetector array (4) through the waveguide. The photodetector in the photodetector array (4) detects the change in light intensity to realize the quantitative measurement of the external magnetic field.

5. The integrated gradient magnetic field sensor based on a cavity optomechanical structure according to claim 1, characterized in that: The multi-channel optical power divider (3) is an N-channel equalization structure, where N≥2, used to evenly distribute the input optical signal to each unit in the cavity optomechanical sensing unit array to ensure the synchronous excitation and detection of multi-point magnetic field signals.

6. The integrated gradient magnetic field sensor based on a cavity optomechanical structure according to claim 1, characterized in that: The optical waveguide structure (2) is formed on the functional layer of the SOI substrate by photolithography and etching processes, and is coupled with the photonic crystal microcavity (11). The resonant signal of the photonic crystal microcavity is transmitted to the photodetector and the spectrum analysis module through the output waveguide for synchronous demodulation of output light intensity changes and mechanical vibration characteristics.

7. The integrated gradient magnetic field sensor based on a cavity optomechanical structure according to claim 1, characterized in that: The mass block (122) is fixed to the functional layer of the SOI substrate by a cantilever beam (121) to form a mechanical resonant structure; the cantilever beam (121) has a length of 100-200μm and a width of 0.5-2μm.

8. The integrated gradient magnetic field sensor based on a cavity optomechanical structure according to claim 1, characterized in that: The photodetector array (4) is used to convert the output optical signal into an electrical signal, detect changes in the output light intensity in real time, and amplify, filter and demodulate the signal to invert the external magnetic field and its gradient. The photodetector array and the cavity optomechanical sensing unit array maintain a consistent spatial spacing to ensure the spatial correspondence and synchronous acquisition accuracy of multi-channel signals.

9. The integrated gradient magnetic field sensor based on a cavity optomechanical structure according to claim 1, characterized in that: The sensor uses an SOI wafer as a substrate during manufacturing. The thickness of the top silicon layer, buried oxide layer, and substrate silicon is set according to the device design requirements. Optical waveguides, photonic crystal microcavities, and mechanically sensitive structures are formed on its functional layers through micro-nano fabrication processes.

10. An integrated gradient magnetic field sensor based on a cavity optomechanical structure according to claim 1, characterized in that: The signal processing amplification, filtering, and demodulation are used to normalize, calibrate, and perform differential operations on the photoelectric output signal of the cavity optomechanical sensing unit array, and generate a two-dimensional gradient magnetic field distribution map to achieve high spatial resolution magnetic field imaging.

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