A high-resolution acceleration sensor based on quasi-bic metasurface and a measuring method

Abstract

The present application relates to the technical field of grating interference acceleration sensor, and particularly relates to a high-resolution acceleration sensor based on quasi-BIC metasurface and a measuring method.The present application solves the problems of low resolution and large ohmic loss of the existing grating interference acceleration sensor.A high-resolution acceleration sensor based on quasi-BIC metasurface comprises a laser, a beam splitter, an acousto-optic modulator, an electro-optic modulator, an optical circulator, a packaging box, a balanced photodetector, an amplifier and a digital instrument;the top wall of the packaging box is provided with a light-transmitting micro-hole;the inner cavity of the packaging box is packaged with a sensitive unit;the sensitive unit comprises two silicon supporting blocks, a silicon mass block, a distributed Bragg reflector, four columns of silicon nitride cantilever beams, a transparent substrate and a quasi-BIC metasurface structure.The present application is suitable for measuring acceleration signals.

Description

Technical Field

[0001] The present invention relates to the technical field of grating interferometric acceleration sensors, and in particular to a high-resolution acceleration sensor based on a quasi-BIC metasurface and a measurement method. Background Art

[0002] Grating interferometry accelerometers are widely used for measuring acceleration signals due to their strong anti-interference capabilities. However, in practical applications, existing grating interferometry accelerometers suffer from the following problems due to their structural limitations: First, the low Q value of the sensitive elements and the wide linewidth of the output spectrum make them incapable of accurately measuring weak acceleration signals, resulting in low resolution. Second, the sensitive elements of existing grating interferometry accelerometers contain metal materials, resulting in large ohmic losses. Quasi-BIC (Bound States in the Continuum) is a special resonant mode based on bound states in the continuum domain within a metasurface. It has an extremely high Q value and a very narrow linewidth, which can greatly enhance the interaction between light and matter. This property gives quasi-BIC great potential for improving sensor resolution. Therefore, it is necessary to develop a high-resolution acceleration sensor and measurement method based on a quasi-BIC metasurface to address the low resolution and large ohmic losses of existing grating interferometry accelerometers. Summary of the Invention

[0003] In order to solve the problems of low resolution and large ohmic loss in existing grating interferometric acceleration sensors, the present invention provides a high-resolution acceleration sensor based on a quasi-BIC metasurface and a measurement method.

[0004] The present invention is achieved by adopting the following technical solutions:

[0005] A high-resolution acceleration sensor based on a quasi-BIC metasurface, comprising a laser, a beam splitter, an acousto-optic modulator, an electro-optic modulator, an optical circulator, a packaging box, a balanced photodetector, an amplifier, and a digitizer;

[0006] The top wall of the packaging box is provided with a light transmission micro hole; the inner cavity of the packaging box encapsulates a sensitive unit; the sensitive unit comprises two silicon support blocks, a silicon mass block, a distributed Bragg reflector, four columns of silicon nitride cantilever beams, a transparent substrate and a quasi-BIC metasurface structure; the two silicon support blocks are both laminated on the inner bottom wall of the packaging box and are symmetrically distributed left and right; the silicon mass block is located between the two silicon support blocks, and the lower surface of the silicon mass block is higher than the lower surfaces of the two silicon support blocks; the distributed Bragg reflector comprises M silicon nitride layers and M silicon dioxide layers which are staggered and laminated together from bottom to top; M is a positive integer and M is greater than or equal to 2; the distributed Bragg reflector is laminated on the upper surface of the silicon mass block, and the upper surface of the distributed Bragg reflector is lower than the upper surfaces of the two silicon support blocks;

[0007] The first column of silicon nitride cantilever beams is connected between the left surface of the silicon mass block and the right surface of the first silicon support block; the second column of silicon nitride cantilever beams is connected between the left surface of the distributed Bragg reflector and the right surface of the first silicon support block; the third column of silicon nitride cantilever beams is connected between the right surface of the silicon mass block and the left surface of the second silicon support block; the fourth column of silicon nitride cantilever beams is connected between the right surface of the distributed Bragg reflector and the left surface of the second silicon support block; the transparent substrate is laminated on the upper surfaces of the two silicon support blocks; the quasi-BIC metasurface structure comprises N wide strip-shaped silicon layers and N narrow strip-shaped silicon layers which are equidistantly and staggeredly arranged in parallel on the upper surface of the transparent substrate; N is a positive integer and N is greater than or equal to 2;

[0008] The exit end of the laser is connected with the entrance end of the beam splitter; the first exit end of the beam splitter is connected with the first entrance end of the balanced photoelectric detector through an acousto-optic modulator; the second exit end of the beam splitter is connected with the first port of the optical circulator through an electro-optic modulator; the second port of the optical circulator is connected with the light transmission micro hole on the packaging box; the third port of the optical circulator is connected with the second entrance end of the balanced photoelectric detector; the signal output end of the balanced photoelectric detector is connected with the signal input end of the digital instrument through an amplifier.

[0009] Each column of silicon nitride cantilever beams comprises a plurality of silicon nitride cantilever beams which are equidistantly and arranged in parallel from front to back; the first column of silicon nitride cantilever beams is connected between the lower edge of the left surface of the silicon mass block and the lower part of the right surface of the first silicon support block; the second column of silicon nitride cantilever beams is connected between the upper part of the left surface of the distributed Bragg reflector and the middle and upper part of the right surface of the first silicon support block; the third column of silicon nitride cantilever beams is connected between the lower edge of the right surface of the silicon mass block and the lower part of the left surface of the second silicon support block; the fourth column of silicon nitride cantilever beams is connected between the upper part of the right surface of the distributed Bragg reflector and the middle and upper part of the left surface of the second silicon support block.

[0010] The inner wall of the packaging box is attached with a shielding foil layer made of ferromagnetic alloy; the inner cavity of the packaging box is a vacuum cavity; a convex lens is embedded in the light transmission micro hole.

[0011] The thickness of each silicon nitride layer is 284.48 nm; and the thickness of each silicon dioxide layer is 156.25 nm.

[0012] The transparent substrate is made of glass.

[0013] The thickness of each wide strip-shaped silicon layer and the thickness of each narrow strip-shaped silicon layer are both 240 nm; the width of each wide strip-shaped silicon layer is 600 nm; and the width of each narrow strip-shaped silicon layer is 400 nm.

[0014] A high-resolution acceleration measurement method based on a quasi-BIC metasurface (the method is implemented based on a high-resolution acceleration sensor based on a quasi-BIC metasurface according to the present application), which is implemented by the following steps:

[0015] First, the sensor is controlled to enter a working mode; the working mode is specifically as follows: the laser emits a probe light, the probe light is incident on a beam splitter, and is divided into two light signals by the beam splitter: the first light signal is incident on a balanced photodetector through an acousto-optic modulator; the second light signal is sequentially incident on the upper surface of a distributed Bragg reflector through an electro-optic modulator, an optical circulator, a light-transmitting micro-hole on a packaging box, a quasi-BIC metasurface structure, and a transparent substrate, and is reflected by the upper surface of the distributed Bragg reflector, and is sequentially incident on the balanced photodetector through the transparent substrate, the quasi-BIC metasurface structure, the light-transmitting micro-hole on the packaging box, and the optical circulator; the two light signals are converted into electrical signals by the balanced photodetector; the electrical signals are transmitted to a digital instrument through an amplifier, and are converted into an output spectrum by the digital instrument;

[0016] In the working mode, when an acceleration signal acts on the silicon mass block, the silicon mass block is displaced up and down, and drives the distributed Bragg reflector to be displaced up and down, thereby causing the frequency of the output spectrum to change; the digital instrument monitors the frequency of the output spectrum before and after the acceleration signal acts on the silicon mass block in real time, and substitutes the frequency of the output spectrum before and after the acceleration signal acts on the silicon mass block into an acceleration measurement equation of the sensor, thereby calculating the acceleration; the acceleration measurement equation of the sensor is expressed as follows:

[0017] ;

[0018] In the formula: represents the acceleration; represents the frequency of the output spectrum after the acceleration signal acts on the silicon mass block; represents the frequency of the output spectrum before the acceleration signal acts on the silicon mass block; represents the gravitational acceleration; represents the output wavelength of the laser; represents the resonant frequency; , 、 All are known quantities.

[0019] Compared with the existing grating interferometric acceleration sensor, the present invention has the following advantages: First, the present invention utilizes the characteristics of quasi-BIC with extremely high Q value and extremely narrow line width to design a sensitive unit with higher Q value, and obtains an output spectrum with narrower line width (such as Figure 5 As shown, compared to the output spectrum of existing grating interferometric acceleration sensors, the output spectrum of the present invention has a narrower linewidth, enabling accurate measurement of weak acceleration signals and effectively improving resolution. Secondly, the sensing unit of the present invention no longer contains metal materials, but instead adopts an all-dielectric structure, effectively reducing ohmic losses.

[0020] The present invention effectively solves the problems of low resolution and large ohmic loss of existing grating interferometric acceleration sensors, and is suitable for measuring acceleration signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] Figure 2 It is a structural diagram of the sensitive unit in the present invention.

[0023] Figure 3 yes Figure 2 Top view of .

[0024] Figure 4 yes Figure 2 Bottom view of .

[0025] Figure 5 The figure is a schematic diagram of the output spectra of the present invention and the existing grating interferometric acceleration sensor.

[0026] In the figure: 1-laser, 2-beam splitter, 3-acousto-optic modulator, 4-electro-optic modulator, 5-optical circulator, 6-packaging box, 7-silicon support block, 8-silicon mass block, 9-silicon nitride layer, 10-silicon dioxide layer, 11-silicon nitride cantilever beam, 12-transparent substrate, 13-wide strip silicon layer, 14-narrow strip silicon layer, 15-balanced photodetector, 16-amplifier, 17-digitizer. DETAILED DESCRIPTION

[0027] A high-resolution acceleration sensor based on a quasi-BIC metasurface includes a laser 1, a beam splitter 2, an acousto-optic modulator 3, an electro-optic modulator 4, an optical circulator 5, a packaging box 6, a balanced photodetector 15, an amplifier 16, and a digitizer 17;

[0028] A light-transmitting microhole is provided through the top wall of the packaging box 6; a sensitive unit is encapsulated in the inner cavity of the packaging box 6; the sensitive unit includes two silicon support blocks 7, a silicon mass block 8, a distributed Bragg reflector, four rows of silicon nitride cantilever beams 11, a transparent substrate 12, and a quasi-BIC metasurface structure; the two silicon support blocks 7 are stacked on the inner bottom wall of the packaging box 6, and the two silicon support blocks 7 are symmetrically distributed on the left and right; the silicon mass block 8 is located between the two silicon support blocks 7, and the lower surface of the silicon mass block 8 is higher than the lower surfaces of the two silicon support blocks 7; the distributed Bragg reflector includes M silicon nitride layers 9 and M silicon dioxide layers 10 stacked together from bottom to top; M is a positive integer, and M≥2; the distributed Bragg reflector is stacked on the upper surface of the silicon mass block 8, and the upper surface of the distributed Bragg reflector is lower than the upper surfaces of the two silicon support blocks 7;

[0029] A first row of silicon nitride cantilever beams 11 is connected between the left surface of the silicon proof mass 8 and the right surface of the first silicon support block 7; a second row of silicon nitride cantilever beams 11 is connected between the left surface of the distributed Bragg reflector and the right surface of the first silicon support block 7; a third row of silicon nitride cantilever beams 11 is connected between the right surface of the silicon proof mass 8 and the left surface of the second silicon support block 7; a fourth row of silicon nitride cantilever beams 11 is connected between the right surface of the distributed Bragg reflector and the left surface of the second silicon support block 7; a transparent substrate 12 is laminated on the upper surfaces of the two silicon support blocks 7 at the same time; the quasi-BIC metasurface structure includes N wide strip silicon layers 13 and N narrow strip silicon layers 14 laminated on the upper surface of the transparent substrate 12 and arranged in parallel and staggered manner at equal intervals; N is a positive integer, and N ≥ 2;

[0030] The output end of the laser 1 is connected to the input end of the beam splitter 2; the first output end of the beam splitter 2 is connected to the first input end of the balanced photodetector 15 through the acousto-optic modulator 3; the second output end of the beam splitter 2 is connected to the first port of the optical circulator 5 through the electro-optic modulator 4; the second port of the optical circulator 5 is connected to the light-transmitting microhole on the packaging box 6; the third port of the optical circulator 5 is connected to the second input end of the balanced photodetector 15; and the signal output end of the balanced photodetector 15 is connected to the signal input end of the digitizer 17 through the amplifier 16.

[0031] Each row of silicon nitride cantilever beams 11 includes multiple silicon nitride cantilever beams 11 arranged in parallel and equidistantly from front to back; the first row of silicon nitride cantilever beams 11 is connected between the lower edge of the left surface of the silicon mass block 8 and the lower part of the right surface of the first silicon support block 7; the second row of silicon nitride cantilever beams 11 is connected between the upper left surface of the distributed Bragg reflector and the upper middle part of the right surface of the first silicon support block 7; the third row of silicon nitride cantilever beams 11 is connected between the lower edge of the right surface of the silicon mass block 8 and the lower part of the left surface of the second silicon support block 7; and the fourth row of silicon nitride cantilever beams 11 is connected between the upper right surface of the distributed Bragg reflector and the upper middle part of the left surface of the second silicon support block 7.

[0032] A shielding foil layer made of ferromagnetic alloy is attached to the inner wall of the packaging box 6; the inner cavity of the packaging box 6 is a vacuum cavity; and a convex lens is sealed and embedded in the light-transmitting microhole.

[0033] The thickness of each silicon nitride layer 9 is 284.48 nm; the thickness of each silicon dioxide layer 10 is 156.25 nm.

[0034] The transparent substrate 12 is made of glass.

[0035] The thickness of each wide strip silicon layer 13 and the thickness of each narrow strip silicon layer 14 are both 240 nm; the width of each wide strip silicon layer 13 is both 600 nm; and the width of each narrow strip silicon layer 14 is both 400 nm.

[0036] A high-resolution acceleration measurement method based on a quasi-BIC metasurface (this method is implemented based on a high-resolution acceleration sensor based on a quasi-BIC metasurface described in the present invention) is implemented using the following steps:

[0037] First, the sensor is controlled to enter the working mode; the working mode is specifically as follows: the laser 1 emits a detection light, the detection light is incident on the beam splitter 2, and is divided into two optical signals by the beam splitter 2: the first optical signal is incident on the balanced photodetector 15 via the acousto-optic modulator 3; the second optical signal is incident on the upper surface of the distributed Bragg reflector via the electro-optic modulator 4, the optical circulator 5, the light-transmitting micro-hole on the packaging box 6, the quasi-BIC metasurface structure, and the transparent substrate 12 in sequence, and then reflected by the upper surface of the distributed Bragg reflector and then incident on the balanced photodetector 15 via the transparent substrate 12, the quasi-BIC metasurface structure, the light-transmitting micro-hole on the packaging box 6, and the optical circulator 5 in sequence; the two optical signals are converted into electrical signals by the balanced photodetector 15; the electrical signals are transmitted to the digitizer 17 via the amplifier 16, and converted into an output spectrum by the digitizer 17;

[0038] In the working mode, when the acceleration signal acts on the silicon mass 8, the silicon mass 8 is displaced up and down, and the distributed Bragg reflector is displaced up and down, thereby changing the frequency of the output spectrum; the digital instrument 17 monitors the frequency of the output spectrum before and after the acceleration signal acts on the silicon mass 8 in real time, and substitutes the frequency of the output spectrum before and after the acceleration signal acts on the silicon mass 8 into the acceleration measurement equation of the sensor, thereby calculating the acceleration; the acceleration measurement equation of the sensor is expressed as follows:

[0039] ;

[0040] In the formula: represents the acceleration; represents the frequency of the output spectrum after the acceleration signal acts on the silicon mass 8; represents the frequency of the output spectrum before the acceleration signal acts on the silicon mass 8; represents the gravitational acceleration; represents the output wavelength of the laser 1; represents the resonance frequency; , , are all known quantities.

[0041] Although the specific embodiments of the present application are described above, those skilled in the art should understand that these are only illustrative, the protection scope of the present application is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present application, and these changes and modifications all fall within the protection scope of the present application.

Claims

1. A high-resolution acceleration sensor based on a quasi-BIC metasurface, characterized by: It includes a laser (1), a beam splitter (2), an acousto-optic modulator (3), an electro-optic modulator (4), an optical circulator (5), a packaging box (6), a balanced photodetector (15), an amplifier (16), and a digitizer (17); The top wall of the packaging box (6) is provided with a light-transmitting microhole; the inner cavity of the packaging box (6) encapsulates a sensitive unit; the sensitive unit comprises two silicon support blocks (7), a silicon mass block (8), a distributed Bragg reflector, four rows of silicon nitride cantilever beams (11), a transparent substrate (12), and a quasi-BIC metasurface structure; the two silicon support blocks (7) are stacked on the inner bottom wall of the packaging box (6), and the two silicon support blocks (7) are symmetrically distributed; the silicon mass block (8) is located between the two silicon support blocks (7), and the lower surface of the silicon mass block (8) is higher than the lower surfaces of the two silicon support blocks (7); the distributed Bragg reflector comprises M silicon nitride layers (9) and M silicon dioxide layers (10) stacked together from bottom to top; M is a positive integer, and M≥2; the distributed Bragg reflector is stacked on the upper surface of the silicon mass block (8), and the upper surface of the distributed Bragg reflector is lower than the upper surfaces of the two silicon support blocks (7); The first row of silicon nitride cantilever beams (11) is connected between the left surface of the silicon mass block (8) and the right surface of the first silicon support block (7); the second row of silicon nitride cantilever beams (11) is connected between the left surface of the distributed Bragg reflector and the right surface of the first silicon support block (7); the third row of silicon nitride cantilever beams (11) is connected between the right surface of the silicon mass block (8) and the left surface of the second silicon support block (7); the fourth row of silicon nitride cantilever beams (11) is connected between the right surface of the distributed Bragg reflector and the left surface of the second silicon support block (7); the transparent substrate (12) is stacked on the upper surfaces of the two silicon support blocks (7) at the same time; the quasi-BIC metasurface structure includes N wide strip silicon layers (13) and N narrow strip silicon layers (14) stacked on the upper surface of the transparent substrate (12) and arranged in parallel and staggered manner at equal intervals; N is a positive integer, and N≥2; The output end of the laser (1) is connected to the input end of the beam splitter (2); the first output end of the beam splitter (2) is connected to the first input end of the balanced photodetector (15) through the acousto-optic modulator (3); the second output end of the beam splitter (2) is connected to the first port of the optical circulator (5) through the electro-optic modulator (4); the second port of the optical circulator (5) is connected to the light-transmitting microhole on the packaging box (6); the third port of the optical circulator (5) is connected to the second input end of the balanced photodetector (15); and the signal output end of the balanced photodetector (15) is connected to the signal input end of the digitizer (17) through the amplifier (16).

2. The high-resolution acceleration sensor based on the quasi-BIC metasurface according to claim 1, characterized in that: Each row of silicon nitride cantilever beams (11) includes a plurality of silicon nitride cantilever beams (11) arranged in parallel and equidistant from front to back; the first row of silicon nitride cantilever beams (11) is connected between the lower edge of the left surface of the silicon mass block (8) and the lower part of the right surface of the first silicon support block (7); the second row of silicon nitride cantilever beams (11) is connected between the upper left surface of the distributed Bragg reflector and the upper middle part of the right surface of the first silicon support block (7); the third row of silicon nitride cantilever beams (11) is connected between the lower edge of the right surface of the silicon mass block (8) and the lower part of the left surface of the second silicon support block (7); and the fourth row of silicon nitride cantilever beams (11) is connected between the upper right surface of the distributed Bragg reflector and the upper middle part of the left surface of the second silicon support block (7).

3. The high-resolution acceleration sensor based on the quasi-BIC metasurface according to claim 1, characterized in that: A shielding foil layer made of ferromagnetic alloy is attached to the inner wall of the packaging box (6); the inner cavity of the packaging box (6) is a vacuum cavity; and a convex lens is sealed and embedded in the light-transmitting micropore.

4. The high-resolution acceleration sensor based on the quasi-BIC metasurface according to claim 1, characterized in that: The thickness of each silicon nitride layer (9) is 284.48 nm; the thickness of each silicon dioxide layer (10) is 156.25 nm.

5. The high-resolution acceleration sensor based on the quasi-BIC metasurface according to claim 1, characterized in that: The transparent substrate (12) is made of glass.

6. The high-resolution acceleration sensor based on the quasi-BIC metasurface according to claim 1, characterized in that: The thickness of each wide strip silicon layer (13) and the thickness of each narrow strip silicon layer (14) are both 240 nm; the width of each wide strip silicon layer (13) is both 600 nm; and the width of each narrow strip silicon layer (14) is both 400 nm.

7. A high-resolution acceleration measurement method based on a quasi-BIC metasurface, the method being implemented based on the high-resolution acceleration sensor based on a quasi-BIC metasurface according to claim 1, characterized in that: This method is implemented using the following steps: First, the sensor is controlled to enter a working mode; the working mode is specifically as follows: the laser (1) emits a detection light, the detection light is incident on the beam splitter (2), and is divided into two optical signals by the beam splitter (2): the first optical signal is incident on the balanced photodetector (15) via the acousto-optic modulator (3); the second optical signal is incident on the upper surface of the distributed Bragg reflector via the electro-optic modulator (4), the optical circulator (5), the light-transmitting microhole on the packaging box (6), the quasi-BIC metasurface structure, and the transparent substrate (12) in sequence, and after being reflected by the upper surface of the distributed Bragg reflector, it is incident on the balanced photodetector (15) via the transparent substrate (12), the quasi-BIC metasurface structure, the light-transmitting microhole on the packaging box (6), and the optical circulator (5) in sequence; the two optical signals are converted into electrical signals by the balanced photodetector (15); the electrical signals are transmitted to the digitizer (17) via the amplifier (16), and are converted into an output spectrum by the digitizer (17); In the working mode, when the acceleration signal acts on the silicon mass block (8), the silicon mass block (8) moves up and down, and drives the distributed Bragg reflector to move up and down, thereby changing the frequency of the output spectrum; the digital instrument (17) monitors the frequency of the output spectrum before and after the acceleration signal acts on the silicon mass block (8) in real time, and substitutes the frequency of the output spectrum before and after the acceleration signal acts on the silicon mass block (8) into the acceleration measurement equation of the sensor, thereby calculating the acceleration; the acceleration measurement equation of the sensor is expressed as follows: ； Where: represents acceleration; represents the frequency of the output spectrum after the acceleration signal acts on the silicon mass block (8); represents the frequency of the output spectrum before the acceleration signal acts on the silicon mass block (8); represents the acceleration due to gravity; represents the output wavelength of the laser (1); represents the resonant frequency; 、 、 All are known quantities.

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