Acceleration sensor and preparation method thereof, and acceleration sensing system

Abstract

The present application relates to the field of acceleration detection technology, and specifically to an acceleration sensor, a preparation method thereof, and an acceleration sensing system. The acceleration sensor includes: a substrate; a first resonant cavity movably disposed on the substrate; a second resonant cavity disposed on the substrate, the second resonant cavity coupled to the first resonant cavity and staggered; when the acceleration sensor is subjected to acceleration, the first resonant cavity moves relative to the second resonant cavity so that the coupling length between the first resonant cavity and the second resonant cavity changes; a bus waveguide disposed on the substrate, the bus waveguide coupled to the second resonant cavity, and the bus waveguide configured to receive laser light and output an optical signal corresponding to the coupling length. This improves the accuracy of acceleration detection and reduces the impact of changes in the external environment on acceleration sensing measurements.

Description

Technical Field

[0001] The present application relates to the technical field of acceleration detection, and in particular to an acceleration sensor and a preparation method thereof, and an acceleration sensing system. Background Art

[0002] With the continuous advancement of science and technology, the demand for precise measurement of the motion state of objects is growing across various fields, prompting the development of accelerometers from traditional simple measurement to high-precision and high-sensitivity. Traditional accelerometers, such as piezoelectric and piezoresistive types, have limited ability to detect small acceleration changes. Furthermore, piezoelectric types have poor low-frequency response, while piezoresistive types are susceptible to temperature effects. In terms of electromagnetic interference resistance, due to their electrical principles, they are susceptible to interference in strong electromagnetic environments, causing errors or even failure.

[0003] Optical microcavity accelerometers, leveraging the strong interaction between light and mechanical structures and the high-resolution optical field, can accurately capture subtle acceleration changes and are used in fields such as aerospace where precision is critical. Furthermore, optical microcavities offer strong resistance to electromagnetic interference. Based on optical principles, optical signals are unaffected by electromagnetic interference, enabling stable measurements in strong electromagnetic environments.

[0004] However, since the optical microring resonator is sensitive to temperature, changes in ambient temperature will also cause the resonance peak to shift in frequency, and the impact of ambient temperature changes on the sensor cannot be eliminated.

[0005] Therefore, there is an urgent need to propose an acceleration sensor with high precision and little influence by temperature. Summary of the Invention

[0006] To solve the above problems, the embodiments of the present application provide an acceleration sensor and a preparation method thereof, as well as an acceleration sensing system, to improve the detection accuracy of acceleration and reduce the impact of external environmental changes on acceleration sensing measurements.

[0007] To achieve the above functions, in a first aspect, an embodiment of the present application provides an acceleration sensor, comprising: a substrate; a first resonant cavity, movably arranged on the substrate; a second resonant cavity, arranged on the substrate, coupled to the first resonant cavity and staggered; wherein, when the acceleration sensor is subjected to acceleration, the first resonant cavity moves relative to the second resonant cavity so that the coupling length between the first resonant cavity and the second resonant cavity changes; a bus waveguide, arranged on the substrate, coupled to the second resonant cavity, and configured to receive laser light and output an optical signal corresponding to the coupling length.

[0008] When the acceleration sensor provided in the embodiment of the present application is subjected to acceleration, the first resonant cavity moves relative to the second resonant cavity to change the coupling length between the first and second resonant cavities, thereby affecting the amplitude change of the optical signal output by the acceleration sensor. Furthermore, a computing device can be used to determine the measured acceleration based on the amplitude change of the optical signal output by the acceleration sensor. Furthermore, because a symmetrical resonant cavity structure is formed between the first and second resonant cavities in the embodiment of the present application, the overall energy distribution of the two resonant cavities does not change when affected by overall environmental changes (such as temperature increases), resulting in the two split resonant peak amplitudes of the output spectrum remaining unchanged, thereby reducing the impact of external environmental changes on acceleration detection.

[0009] In a possible implementation, both the first resonant cavity and the second resonant cavity are racetrack resonant cavities.

[0010] In a possible implementation, the sidewall lengths of the first resonant cavity and the second resonant cavity are both ; The value range of coupling length is .

[0011] In one possible implementation, the acceleration sensor also includes: a first cantilever beam, disposed on the substrate, with a first end of the first cantilever beam connected to the substrate, and a second end of the first cantilever beam connected to the first resonant cavity; a second cantilever beam, disposed on the substrate, with a first end of the second cantilever beam connected to the substrate, and a second end of the second cantilever beam connected to the first resonant cavity; when subjected to acceleration, the first cantilever beam and the second cantilever beam expand and contract to drive the first resonant cavity to move relative to the second resonant cavity.

[0012] In a possible implementation, the first cantilever beam and the second cantilever beam are both serpentine cantilever beams.

[0013] In one possible implementation, the acceleration sensor also includes: a accommodating cavity, opened in the substrate; the first end of the first cantilever beam is connected to the first cavity wall of the accommodating cavity; the first end of the second cantilever beam is connected to the second cavity wall of the accommodating cavity; the first cavity wall and the second cavity wall are cavity walls opposite to each other of the accommodating cavity.

[0014] In one possible implementation, the acceleration sensor further includes: a first spot mode converter, disposed at the first end of the bus waveguide, and configured to receive laser light; and a second spot mode converter, disposed at the second end of the bus waveguide, and configured to output an optical signal.

[0015] In a second aspect, an embodiment of the present application further provides a method for preparing an acceleration sensor, wherein the substrate includes a silicon layer, a silicon dioxide layer, and a silicon thin film layer; the method for preparing the acceleration sensor includes: exposing areas corresponding to the bus waveguide, the first resonant cavity, and the second resonant cavity on the silicon thin film layer; etching on the silicon thin film layer to form a planar waveguide device; again exposing an area corresponding to the coupling area between the first resonant cavity and the second resonant cavity on the silicon thin film layer; etching on the planar waveguide device to form a strip waveguide device; etching on the silicon dioxide layer to separate the first resonant cavity from the silicon dioxide layer, thereby obtaining the acceleration sensor provided by the first aspect above and any optional implementation thereof.

[0016] The method for preparing an acceleration sensor provided in the embodiment of the present application can produce a highly sensitive acceleration sensor, which can improve the detection accuracy of acceleration and reduce the impact of changes in the external environment on acceleration sensing measurements.

[0017] In a third aspect, an embodiment of the present application further provides an acceleration sensing system, comprising: an acceleration sensor, comprising the acceleration sensor provided in the first aspect and any possible implementation thereof, or an acceleration sensor prepared by the method for preparing an acceleration sensor provided in the second aspect; a laser, the laser being disposed at the first end of the bus waveguide, the laser being configured to output laser light; a photodetector, the photodetector being disposed at the second end of the bus waveguide, the photodetector being configured to receive light output by the bus waveguide and convert it into an electrical signal; and a computing device being communicatively connected to the photodetector, the computing device being configured to receive the electrical signal and determine acceleration based on the electrical signal.

[0018] The acceleration sensing system provided in the embodiments of the present application can improve the detection accuracy and response speed of acceleration and reduce the impact of environmental changes on acceleration detection results.

[0019] In one possible implementation, the computing device is configured to: construct a current spectrum based on the electrical signal; determine an amplitude deviation between the current spectrum and an initial spectrum; the initial spectrum corresponds to a spectrum when the acceleration is 0; and determine the acceleration corresponding to the current spectrum based on the amplitude deviation and a mapping relationship. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0021] Figure 1 This is a schematic structural diagram of an acceleration sensing system provided in an embodiment of the present application;

[0022] Figure 2 is a schematic structural diagram of an acceleration sensor provided in an embodiment of the present application;

[0023] Figure 3 Schematic diagram of the non-offset arrangement of the first resonant cavity and the second resonant cavity provided in an embodiment of the present application;

[0024] Figure 4 Schematic diagram of the staggered arrangement of the first resonant cavity and the second resonant cavity provided in an embodiment of the present application;

[0025] Figure 5 Schematic diagram of the output spectrum of the acceleration sensor provided in the embodiment of the present application;

[0026] Figure 6 Schematic diagram of the movement of the first cantilever beam, the second cantilever beam and the first resonant cavity provided in an embodiment of the present application;

[0027] Figure 7 1 is a flow chart of a method for preparing an acceleration sensor provided in an embodiment of the present application;

[0028] Figure 8 is a flowchart of a method for preparing an acceleration sensor provided in an embodiment of the present application;

[0029] Figure 9 This is another structural diagram of the acceleration sensing system provided in an embodiment of the present application.

[0030] Reference numerals:

[0031] 100. Acceleration sensing system;

[0032] 1. Laser;

[0033] 2. Accelerometer; 21. Substrate; 211. Silicon layer; 212. Silicon dioxide layer; 213. Silicon thin film layer; 214. Photoresist; 22. First resonant cavity; 23. Second resonant cavity; 24. Bus waveguide; 25. First cantilever beam; 26. Second cantilever beam; 27. Accommodation cavity; 28. First spot mode converter; 29. ​​Second spot mode converter;

[0034] 3. Photodetector;

[0035] 4. Computing devices; 41. Mobile phones; 42. Desktop computers. DETAILED DESCRIPTION

[0036] The following will clearly describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, other embodiments obtained by ordinary technicians in this field without making any creative work are all within the scope of protection of this application.

[0037] Hereinafter, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified with "first," "second," etc., may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0038] In addition, in this application, directional terms such as "upper", "lower", "inner" and "outer" are defined relative to the orientation of the components in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative description and clarification, and they can change accordingly according to changes in the orientation of the components in the drawings.

[0039] To facilitate understanding of the technical solution of the application, the relevant technologies involved in this application are first explained below.

[0040] With the continuous advancement of science and technology, the demand for precise measurement of the motion state of objects is growing across various fields. Accelerometers, as essential components for accurate motion measurement, are driving the evolution of accelerometers from traditional simple measurement to high-precision, high-sensitivity capabilities. Furthermore, the maturity of advanced manufacturing technologies such as micro-electro-mechanical systems (MEMS) has enabled accelerometers to be miniaturized, integrated, and low-power, meeting the application requirements of modern electronic devices and complex systems. Accelerometers play a key role in numerous fields, including automotive safety, aerospace, robotics, and biomedicine. Their expanding application scope is driving the continuous innovation and improvement of related technologies.

[0041] Related technologies include piezoelectric and piezoresistive accelerometers. However, these sensors have low detection accuracy, limiting their ability to detect even small acceleration changes. Furthermore, piezoelectric sensors have poor low-frequency response, while piezoresistive sensors are susceptible to temperature fluctuations. Furthermore, due to their electrical principles, they are susceptible to interference in strong electromagnetic environments, leading to errors or even malfunction.

[0042] To solve the above problems, the embodiments of the present application propose an acceleration sensor 2 and a preparation method thereof, and an acceleration sensing system 100, which realize acceleration sensing based on an optical microcavity. Compared with traditional piezoelectric and piezoresistive acceleration sensors, it has higher sensitivity and resolution.

[0043] Figure 1 This is a structural diagram of the acceleration sensing system provided in an embodiment of the present application.

[0044] Reference Figure 1 As shown, an embodiment of the present application provides an acceleration sensing system 100 , including: a laser 1 , an acceleration sensor 2 , a photodetector 3 and a computing device 4 .

[0045] Among them, the laser 1, the acceleration sensor 2 and the photodetector 3 are optically connected in sequence (such as Figure 1 The photoelectric detector 3 and the computing device 4 are connected in communication (e.g. Figure 1 (schematically indicated by dashed arrows).

[0046] The acceleration sensor 2 receives the laser light emitted by the laser 1 and outputs a light signal corresponding to the acceleration.

[0047] The photodetector 3 receives the optical signal output by the acceleration sensor 2 and converts it into an electrical signal.

[0048] The computing device 4 is configured to receive the electrical signal and determine the acceleration based on the electrical signal.

[0049] The acceleration sensing system 100 provided in the embodiment of the present application outputs a light signal corresponding to the acceleration based on the influence of acceleration on the acceleration sensor 2. The acceleration is then demodulated and determined based on the light signal corresponding to the acceleration to achieve acceleration measurement.

[0050] Specifically, after the acceleration sensor 2 is affected by acceleration, the components inside the acceleration sensor 2 will change the amplitude of the light output by the acceleration sensor 2 under the influence of acceleration, and then the acceleration can be determined based on the amplitude change of the output light signal of the acceleration sensor 2, thereby realizing the detection of acceleration.

[0051] It is worth noting that the computing device 4 may include a mobile phone 41, a tablet computer, a desktop computer 42, a laptop computer, a mobile computing device or an industrial computer, etc., and this application does not impose any restrictions on this.

[0052] Figure 2 Schematic diagram of the structure of the acceleration sensor provided in the embodiment of the present application.

[0053] Combine Figure 1 The acceleration sensing system 100 shown in FIG. Figure 2As shown, the embodiment of the present application further provides an acceleration sensor 2 , including: a substrate 21 , a first resonant cavity 22 , a second resonant cavity 23 and a bus waveguide 24 .

[0054] The first resonant cavity 22 , the second resonant cavity 23 and the bus waveguide 24 are coupled in sequence and arranged on the substrate 21 .

[0055] The first resonant cavity 22 is movably disposed on the substrate 21 .

[0056] The second resonant cavity 23 is offset from the first resonant cavity 22. In this way, under the action of acceleration, the coupling length between the first resonant cavity 22 and the second resonant cavity 23 can be increased or decreased, thereby affecting the amplitude of the output light and changing its direction, thereby measuring the direction of the acceleration.

[0057] The bus waveguide 24 is configured to receive laser light and output an optical signal corresponding to a coupling length.

[0058] When the accelerometer 2 provided in the embodiment of the present application is subjected to acceleration, the first resonant cavity 22 moves relative to the second resonant cavity 23, thereby changing the coupling length between the first resonant cavity 22 and the second resonant cavity 23, thereby affecting the amplitude change of the optical signal output by the accelerometer 2. Furthermore, the computing device 4 can determine the measured acceleration based on the amplitude change of the optical signal output by the accelerometer 2.

[0059] Furthermore, since a symmetrical resonant cavity structure is formed between the first resonant cavity 22 and the second resonant cavity 23 in the embodiment of the present application, the overall energy distribution of the two resonant cavities will not change when affected by overall environmental changes (such as temperature increase), resulting in the two split resonant peak amplitudes of the output spectrum not changing, thereby reducing the impact of external environmental changes on acceleration detection.

[0060] Specifically, the laser output by the laser 1 enters the bus waveguide 24 and then enters the second resonant cavity 23 coupled to the bus waveguide 24 through the evanescent field. The light in the second resonant cavity 23 passes through and enters the first resonant cavity 22 coupled to the second resonant cavity 23.

[0061] Figure 3 Schematic diagram of the non-displacement arrangement of the first resonant cavity and the second resonant cavity provided in the embodiment of the present application. Figure 3 (a) is a schematic diagram of the relative position of L of the first resonant cavity 22 and the second resonant cavity 23 when the acceleration is 0. Figure 3 (b) is a schematic diagram of the relative positions of the first resonant cavity 22 and the second resonant cavity 23 when the acceleration is not zero and the direction is the first direction. Figure 3(c) is a schematic diagram of the relative positions of the first resonant cavity 22 and the second resonant cavity 23 when the acceleration is non-zero and the direction is the second direction. The first direction and the second direction are opposite directions.

[0062] Combine Figure 3 As shown, if the first resonant cavity 22 and the second resonant cavity 23 are not offset, the initial positions of the first resonant cavity 22 and the second resonant cavity 23 are as follows: Figure 3 As shown in (a).

[0063] like Figure 3 As shown in (b), when subjected to the acceleration in the first direction, the first resonant cavity 22 moves in the first direction, that is, the first resonant cavity 22 moves to the left relative to the second resonant cavity 23, reducing the coupling length L between the first resonant cavity 22 and the second resonant cavity 23. C .

[0064] like Figure 3 As shown in (c), when subjected to the acceleration in the second direction, the first resonant cavity 22 moves in the second direction, that is, the first resonant cavity 22 moves to the right relative to the second resonant cavity 23, reducing the coupling length L between the first resonant cavity 22 and the second resonant cavity 23. C .

[0065] In summary, regardless of the direction of acceleration, the coupling length between the first resonant cavity 22 and the second resonant cavity 23 will become smaller. Therefore, this arrangement of the first resonant cavity 22 and the second resonant cavity 23 can only detect the magnitude of acceleration, but not its direction, and has low practicality.

[0066] Figure 4 Schematic diagram of the staggered arrangement of the first resonant cavity and the second resonant cavity provided in the embodiment of the present application. Figure 4 (a) is a schematic diagram of the relative positions of the first resonant cavity 22 and the second resonant cavity 23 when the acceleration is 0. Figure 4 (b) is a schematic diagram of the relative positions of the first resonant cavity 22 and the second resonant cavity 23 when the acceleration is not zero and the direction is the first direction. Figure 4 (c) is a schematic diagram of the relative positions of the first resonant cavity 22 and the second resonant cavity 23 when the acceleration is non-zero and the direction is the second direction. The first direction and the second direction are opposite directions.

[0067] Combine Figure 4 As shown, if the first resonant cavity 22 and the second resonant cavity 23 are staggered, the initial positions of the first resonant cavity 22 and the second resonant cavity 23 are as follows: Figure 4 As shown in (a).

[0068] like Figure 4As shown in (b), when subjected to the acceleration in the first direction, the first resonant cavity 22 moves in the first direction, that is, the first resonant cavity 22 moves to the left relative to the second resonant cavity 23, increasing the coupling length L between the first resonant cavity 22 and the second resonant cavity 23. C .

[0069] like Figure 4 As shown in (c), when subjected to the acceleration in the second direction, the first resonant cavity 22 moves in the second direction, that is, the first resonant cavity 22 moves to the right relative to the second resonant cavity 23, reducing the coupling length L between the first resonant cavity 22 and the second resonant cavity 23. C .

[0070] In summary, by staggering the first resonant cavity 22 and the second resonant cavity 23, the coupling length L between the first resonant cavity 22 and the second resonant cavity 23 can be reduced to C The change of is different, that is, the coupling length L is different when the direction of acceleration is different C Increase or decrease, rather than decrease both. In this way, the coupling length L C The different changes in the amplitude of the light signal output by the acceleration sensor 2 cause different changes, and the magnitude and direction of the acceleration corresponding to the amplitude change can be demodulated.

[0071] For example, when the magnitude of the acceleration is -1g and the direction is the first direction, the amplitude change is -0.1. When the magnitude of the acceleration is +1g and the direction is the second direction, the amplitude change is 0.1.

[0072] Figure 5 Schematic diagram of the output spectrum of the acceleration sensor provided in the embodiment of the present application.

[0073] For example, refer to Figure 5 As shown, when the acceleration is 0, the coupling length L between the first resonant cavity 22 and the second resonant cavity 23 is C unchanged, that is, the coupling length change ΔL=0μm, the output spectrum of acceleration sensor 2 is as follows Figure 5 As shown in the middle curve A.

[0074] When the acceleration is in the first direction, the first resonant cavity 22 moves to the left relative to the second resonant cavity 23 (e.g. Figure 4 As shown in (b), the coupling length L between the first resonant cavity 22 and the second resonant cavity 23 C Increase, the coupling length change ΔL=+1μm, the output spectrum of acceleration sensor 2 is as follows Figure 5 As shown in the middle curve B.

[0075] When the acceleration is in the second direction, the first resonant cavity 22 moves to the right relative to the second resonant cavity 23 (eg Figure 4 As shown in (c), the coupling length L between the first resonant cavity 22 and the second resonant cavity 23 C The coupling length changes by ΔL=-1μm, and the output spectrum of the acceleration sensor 2 is as follows: Figure 5 As shown in the middle curve C.

[0076] Combine Figure 5 It can be seen that the relative amplitude between the two resonance peaks split by curve A is larger than the relative amplitude between the two resonance peaks of curve B, and the relative amplitude between the two resonance peaks split by curve A is smaller than the relative amplitude between the two resonance peaks of curve C.

[0077] Specifically, combined Figure 5 It can be seen that the two resonance peaks of curve A before acceleration occurs (i.e. when the acceleration is 0) are A1 and A2 respectively. The relative magnitude of the amplitudes of the two resonance peaks can be calculated, i.e. the initial amplitude difference is: T(A1)-T(A2) / T(A1), which is the value when there is no acceleration feedback. When acceleration occurs, if the coupling length between the first resonant cavity 22 and the second resonant cavity 23 changes by ΔL=1μm, as shown in Figure 5 As shown in curve B, the resonance peaks now become B1 and B2. The relative magnitude of the amplitudes of the two resonance peaks can be calculated, that is, the current amplitude difference is: T(B1)-T(B2) / T(B1). By comparing the two values, the acceleration change can be obtained.

[0078] In one implementation, both the first resonant cavity 22 and the second resonant cavity 23 are racetrack-type resonant cavities. This increases the coupling length between the first resonant cavity 22 and the second resonant cavity 23, and when the coupling length changes, the output spectrum of the acceleration sensor 2 changes significantly.

[0079] For example, the sidewall lengths of the first resonant cavity 22 and the second resonant cavity 23 are both The coupling length range is Thus, when the coupling length within this range is the initial coupling length, regardless of the direction of acceleration, the first resonant cavity 22 and the second resonant cavity 23 maintain coupling while also having a good left-right movement space, thereby reducing the problem of no longer coupling when the first resonant cavity 22 and the second resonant cavity 23 move relative to each other.

[0080] Figure 6 Schematic diagram of the movement of the first cantilever beam, the second cantilever beam and the first resonant cavity provided in the embodiment of the present application. Figure 6 (a) corresponds to an acceleration of 0, Figure 6(b) corresponds to non-zero and the direction is the first direction, Figure 6 (c) corresponds to the acceleration being non-zero and in the second direction.

[0081] In one implementation, combining Figure 2 and Figure 6 As shown, the acceleration sensor 2 further includes a first cantilever beam 25 and a second cantilever beam 26 .

[0082] The first cantilever beam 25 is disposed on the substrate 21, with a first end of the first cantilever beam 25 connected to the substrate 21 and a second end of the first cantilever beam 25 connected to the first resonant cavity 22. The second cantilever beam 26 is disposed on the substrate 21, with a first end of the second cantilever beam 26 connected to the substrate 21 and a second end of the second cantilever beam 26 connected to the first resonant cavity 22. When subjected to acceleration, the first and second cantilever beams 25 and 26 expand and contract, thereby causing the first resonant cavity 22 to move relative to the second resonant cavity 23.

[0083] In this embodiment, the first resonant cavity 22 can be driven to move by the extension and contraction of the first cantilever beam 25 and the second cantilever beam 26 , so that the first resonant cavity 22 maintains stable movement.

[0084] Specifically, refer to Figure 6 As shown in (a), when the acceleration sensor 2 is not subjected to acceleration, the first cantilever beam 25 and the second cantilever beam 26 maintain their initial states.

[0085] When the acceleration is in the first direction, the first resonant cavity 22 moves to the left relative to the second resonant cavity 23 (e.g. Figure 6 As shown in (b), the first cantilever beam 25 is compressed compared to the initial state, and the second cantilever beam 26 is extended compared to the initial state, so that the first resonant cavity 22 moves leftward relative to the second resonant cavity 23.

[0086] When the acceleration is in the second direction, the first resonant cavity 22 moves to the right relative to the second resonant cavity 23 (eg Figure 6 As shown in (c), the first cantilever beam 25 is extended compared to the initial state, and the second cantilever beam 26 is compressed compared to the initial state, so that the first resonant cavity 22 moves rightward relative to the second resonant cavity 23.

[0087] For example, the first cantilever beam 25 and the second cantilever beam 26 are both serpentine cantilever beams. In this way, the first cantilever beam 25 and the second cantilever beam 26 can be extended and retracted by the serpentine structure, and the stability of the first cantilever beam 25 and the second cantilever beam 26 when not subjected to acceleration can be improved.

[0088] In one implementation, the first resonant cavity 22 is suspended relative to the substrate 21 , so that the friction caused by the substrate 21 on the movement of the first resonant cavity 22 can be reduced, thereby reducing the influence of the substrate 21 on the movement of the first resonant cavity 22 .

[0089] In one implementation, combining Figure 2 As shown, the acceleration sensor 2 further includes an accommodating cavity 27 .

[0090] The accommodating cavity 27 is formed in the substrate 21. The first end of the first cantilever beam 25 is connected to the first cavity wall of the accommodating cavity 27. The first end of the second cantilever beam 26 is connected to the second cavity wall of the accommodating cavity 27. The first cavity wall and the second cavity wall are opposite cavity walls of the accommodating cavity 27.

[0091] In this embodiment, the first resonant cavity 22 is suspended relative to the substrate 21 to reduce the frictional force of the substrate 21 on the movement of the first resonant cavity 22 and the influence of the substrate 21 on the movement of the first resonant cavity 22 .

[0092] In one implementation, combining Figure 2 As shown, the acceleration sensor 2 further includes a first pattern spot converter 28 and a second pattern spot converter 29 .

[0093] The first spot converter 28 is disposed at the first end of the bus waveguide 24 and is configured to receive laser light, while the second spot converter 29 is disposed at the second end of the bus waveguide 24 and is configured to output optical signals.

[0094] Specifically, the first spot mode converter 28 is used to receive the laser output by the laser 1 , and the optical signal output by the second spot mode converter 29 is the optical signal corresponding to the coupling length between the first resonant cavity 22 and the second resonant cavity 23 output by the acceleration sensor 2 .

[0095] The incident light generated by the laser 1 is coupled into the bus waveguide 24 by the spot converter and coupled into the racetrack resonant cavity in the form of an evanescent field. Light that meets the resonant cavity's resonance conditions will remain in the resonant cavity in the form of a standing wave, while light that does not meet the conditions will not be coupled into the resonant cavity. Among them, the light that meets the resonant cavity's resonance conditions satisfies:

[0096] Among them, the light that meets the resonance conditions of the resonant cavity satisfies:

[0097] ;

[0098] in, is the radius of the second resonant cavity 23, is the wavelength of incident light, is the effective refractive index of the waveguide, and m (m=1, 2, 3…) is the mode number.

[0099] The accelerometer 2 provided in the present embodiment, through its structural design combining a coupled racetrack-shaped resonant cavity with a serpentine cantilever beam, offers higher sensitivity and resolution than conventional piezoelectric and piezoresistive accelerometers 2. The coupled resonant cavity structure creates a split resonance peak, and by measuring the relative change in the resonance peak amplitude, it mitigates the effects of ambient temperature on the measurement.

[0100] Figure 7 is a flow chart of a method for preparing an acceleration sensor provided in an embodiment of the present application, Figure 8 This is a production flow chart of the method for preparing the acceleration sensor provided in an embodiment of the present application.

[0101] Combine Figure 2 The acceleration sensor 2 shown in the embodiment of the present application provides a method for preparing the acceleration sensor 2, wherein the substrate 21 includes a silicon layer 211, a silicon dioxide layer 212 and a silicon thin film layer 213 in sequence. Figure 7 As shown, the method for preparing the acceleration sensor 2 includes the following steps S1-S5.

[0102] The thickness of the silicon thin film layer 213 is 220 nm and is used for etching the device layer. The thickness of the silicon dioxide layer 212 is 2 μm and is used as a sacrificial layer when etching the suspension area.

[0103] For example, the structure of the substrate 21 is as follows Figure 8 As shown in (a).

[0104] S1 , exposing the areas corresponding to the bus waveguide 24 , the first resonant cavity 22 , and the second resonant cavity 23 on the silicon thin film layer 213 .

[0105] In this step, electron beam lithography is used to expose the first spot converter 28, the second spot converter 29, the bus waveguide 24, the first resonant cavity 22, the second resonant cavity 23, the first cantilever beam 25 and the second cantilever beam 26. The obtained structure is as shown in FIG. Figure 8 Specifically, a portion of the silicon thin film layer 213 is covered with a photoresist 214 .

[0106] S2, etching on the silicon thin film layer 213 to form a planar waveguide device.

[0107] In this step, the waveguide layer is etched using inductively coupled plasma etching to a depth of 170 nm to form a slab waveguide device. The resulting structure is as follows: Figure 8 As shown in (c).

[0108] S3 , exposing again the area corresponding to the coupling area between the first resonant cavity 22 and the second resonant cavity 23 on the silicon thin film layer 213 .

[0109] In this step, electron beam lithography is again used to expose the coupling region of the first cantilever beam 25, the second cantilever beam 26, the first resonant cavity 22 and the second resonant cavity 23. The obtained structure is as shown in FIG. Figure 8 Specifically, a portion of the silicon thin film layer 213 is covered with a photoresist 214 .

[0110] S4, etching on the planar waveguide device to form a strip waveguide device.

[0111] In this step, the planar waveguide device is etched using inductively coupled plasma etching with an etching depth of 50 nm to form a strip waveguide. The resulting structure is as follows: Figure 8 As shown in (e).

[0112] S5, etching the silicon dioxide layer 212 to separate the first resonant cavity 22 from the silicon dioxide layer 212. In this way, the acceleration sensor 2 provided in any of the above embodiments is obtained.

[0113] In this step, hydrofluoric acid vapor etching is used to release the first resonant cavity 22 so that the first resonant cavity 22 is suspended in the air. The resulting structure is as follows: Figure 8 As shown in (f).

[0114] By adopting the preparation method of the acceleration sensor 2 provided in the embodiment of the present application, a high-sensitivity acceleration sensor 2 can be prepared, which can improve the detection accuracy of acceleration and reduce the impact of external environmental changes on acceleration sensing measurement.

[0115] Moreover, during the process, a planar waveguide is formed directly on the silicon film by shallow etching, and the non-etched area can be protected during hydrofluoric acid vapor etching without depositing other materials, making the process simpler.

[0116] Figure 9 This is another structural diagram of the acceleration sensing system provided in an embodiment of the present application.

[0117] Corresponding to the above-mentioned acceleration sensor 2 and the method for preparing the acceleration sensor 2, the present application also provides an acceleration sensing system 100, such as Figure 9 As shown, the acceleration sensing system 100 includes: a laser 1, an acceleration sensor 2, a photodetector 3 and a computing device 4.

[0118] The acceleration sensor 2 includes the acceleration sensor 2 provided in any one of the above embodiments, or the acceleration sensor 2 prepared by the preparation method of the acceleration sensor 2 provided in the above embodiments.

[0119] The laser 1 is disposed at a first end of the bus waveguide 24 , and the laser 1 is configured to output laser light.

[0120] The photodetector 3 is disposed at the second end of the bus waveguide 24 . The photodetector 3 is configured to receive light outputted by the bus waveguide 24 and convert the light into an electrical signal.

[0121] The computing device 4 is communicatively connected to the photodetector 3 , and is configured to receive the electrical signal and determine the acceleration based on the electrical signal.

[0122] The acceleration sensing system 100 provided in the embodiment of the present application can improve the detection accuracy and response speed of acceleration and reduce the impact of environmental changes on the acceleration detection results.

[0123] In one implementation, the computing device 4 is specifically configured to perform the following steps S101 - S103 .

[0124] S101, constructing a current spectrum based on the electrical signal.

[0125] S102: Determine the amplitude deviation between the current spectrum and the initial spectrum. The initial spectrum corresponds to the spectrum when the acceleration is zero.

[0126] S103: Determine the acceleration corresponding to the current spectrum based on the amplitude deviation and the mapping relationship.

[0127] In this embodiment, by constructing the current spectrum and comparing the relative change in the resonance peak amplitude between the current spectrum and the initial spectrum, the amplitude deviation is determined, so that the acceleration corresponding to the current amplitude deviation can be determined according to the size of the amplitude deviation and the preset mapping relationship, thereby obtaining the current acceleration.

[0128] Specifically, the acceleration sensing system 100 determines the amplitude deviation of the optical signal by comparing the output spectrum when the acceleration is 0 with the output spectrum under the current acceleration.

[0129] The mapping relationship can be to actively adjust the acceleration to obtain different spectra corresponding to each acceleration, so as to calculate the amplitude deviation between the spectrum under each acceleration and the spectrum when the acceleration is 0, so as to construct a comparison table of amplitude deviation and acceleration.

[0130] Specifically, the mapping relationship may also be a mapping relationship table among acceleration, coupling length, and amplitude deviation.

[0131] It should be noted that those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered merely as exemplary, and the true scope of this application is indicated by the claims.

[0132] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. An acceleration sensor, characterized in that: include: substrate (21); A first resonant cavity (22) movably disposed on the substrate (21); a second resonant cavity (23) disposed on the substrate (21), the second resonant cavity (23) being coupled to the first resonant cavity (22) and being staggered; Wherein, when the acceleration sensor is subjected to acceleration, the first resonant cavity (22) moves relative to the second resonant cavity (23), so that the coupling length between the first resonant cavity (22) and the second resonant cavity (23) changes; A bus waveguide (24) is provided on the substrate (21), the bus waveguide (24) is coupled with the second resonant cavity (23), and the bus waveguide (24) is configured to receive laser light and output an optical signal corresponding to the coupling length; The first resonant cavity (22) and the second resonant cavity (23) are both racetrack-type resonant cavities; The sidewall lengths of the first resonant cavity (22) and the second resonant cavity (23) are both L; The coupling length range is ; a first cantilever beam (25) disposed on the substrate (21), wherein a first end of the first cantilever beam (25) is connected to the substrate (21), and a second end of the first cantilever beam (25) is connected to the first resonant cavity (22); a second cantilever beam (26) disposed on the substrate (21), wherein a first end of the second cantilever beam (26) is connected to the substrate (21), and a second end of the second cantilever beam (26) is connected to the first resonant cavity (22); When the acceleration sensor is subjected to acceleration, the first cantilever beam (25) and the second cantilever beam (26) expand and contract to drive the first resonant cavity (22) to move relative to the second resonant cavity (23); an accommodating cavity (27) formed in the substrate (21); The first end of the first cantilever beam (25) is connected to the first cavity wall of the accommodating cavity (27); The first end of the second cantilever beam (26) is connected to the second cavity wall of the accommodating cavity (27); The first cavity wall and the second cavity wall are cavity walls opposite to the accommodating cavity (27).

2. The acceleration sensor according to claim 1, wherein The first cantilever beam (25) and the second cantilever beam (26) are both serpentine cantilever beams.

3. The acceleration sensor according to claim 1 or 2, characterized in that Also includes: A first spot mode converter (28) is disposed at a first end of the bus waveguide (24), wherein the first spot mode converter (28) is configured to receive laser light; The second spot mode converter (29) is arranged at the second end of the bus waveguide (24), and the second spot mode converter (29) is configured to output an optical signal.

4. A method for preparing an acceleration sensor, characterized in that: The substrate (21) comprises a silicon layer (211), a silicon dioxide layer (212) and a silicon thin film layer (213), and the preparation method comprises: exposing areas corresponding to the bus waveguide (24), the first resonant cavity (22), and the second resonant cavity (23) on the silicon thin film layer (213); Etching on the silicon thin film layer (213) to form a planar waveguide device; exposing again on the silicon thin film layer (213) an area corresponding to the coupling area between the first resonant cavity (22) and the second resonant cavity (23); Etching on the planar waveguide device to form a strip waveguide device; The silicon dioxide layer (212) is etched to separate the first resonant cavity (22) from the silicon dioxide layer (212), thereby obtaining the acceleration sensor according to any one of claims 1 to 3.

5. An acceleration sensing system, characterized in that: include: The acceleration sensor (2) according to any one of claims 1 to 3, or the acceleration sensor (2) prepared by the method for preparing an acceleration sensor according to claim 4; A laser (1), the laser (1) being disposed at a first end of the bus waveguide (24), the laser (1) being configured to output laser light; a photodetector (3), the photodetector (3) being arranged at the second end of the bus waveguide (24), the photodetector (3) being configured to receive light output by the bus waveguide (24) and convert the light into an electrical signal; A computing device (4) is communicatively connected to the photodetector (3), and the computing device (4) is configured to receive the electrical signal and determine acceleration based on the electrical signal.

6. The acceleration sensing system according to claim 5, characterized in that: The computing device (4) is configured to: constructing a current spectrum based on the electrical signal; Determining an amplitude deviation between the current spectrum and an initial spectrum; the initial spectrum corresponds to a spectrum when the acceleration is 0; Based on the amplitude deviation, the acceleration corresponding to the current spectrum is determined according to a mapping relationship.

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