Sensing method and system of echo wall mode microcavity time-varying signal

Abstract

The invention provides an echo wall mode microcavity time-varying signal sensing method and system. The echo wall mode microcavity time-varying signal sensing method comprises the steps of S1, building an echo wall mode microcavity time-varying signal sensing experiment platform based on a double-optical-comb spectrum technology; s2, starting a dual-light frequency comb; s3, sensing a time-varying signal through coupling of a coupling device and the echo wall mode microcavity; s4, performing Fourier transform on the output of the reference path and the signal path within one sampling time, and extracting a time-varying signal by using a plurality of modes of the microcavity; and S5, repeatedly executing the step S4 until the measurement is finished. Time-varying parameter sensing is achieved through multiple modes of the microcavity, high sensitivity is achieved, meanwhile, high precision and a large dynamic range are achieved, and application of microcavity sensing is further expanded.

Description

Technical Field

[0001] The present invention relates to the technical fields of optoelectronic detection and signal processing and microcavity sensing technology. Specifically, it relates to a sensing method and system for time-varying signals of a whispering gallery mode microcavity. In particular, it relates to a sensing method and system for time-varying signals of a whispering gallery mode microcavity based on dual-comb spectroscopy technology. Background Art

[0002] The whispering gallery mode microcavity has a high quality factor, which greatly enhances the interaction between light and matter in the microcavity. High-sensitivity measurements have been achieved in aspects such as biosensing, single nanoparticle detection, chemical sensing, refractive index sensing, temperature sensing, magnetic field sensing, chemical gas sensing, pressure sensing, and acoustic sensing, and it has a wide range of applications.

[0003] When using a whispering gallery microcavity for sensing, the research focuses on using the sensing of a single mode of the microcavity, and there are mainly two measurement methods. One is to measure its transmission spectrum through a tunable laser, and realize sensing by observing the shift of its resonance frequency. The sensitivity of this sensing method is directly related to the microcavity, and its dynamic range is related to the tuning range of the laser and the free spectral range of the microcavity. Since a tunable laser is used for frequency sweeping, there is a long time interval in the measurement, and it can only be applied to static signals and slowly varying signals. The other is to observe the change in intensity at a fixed wavelength through a single-frequency laser. The sensitivity of this sensing method is directly related to the quality factor of the microcavity, but the dynamic range is also restricted by the quality factor at the same time. The dynamic ranges of both are limited to a single mode of the microcavity and are difficult to improve. In recent years, researchers have achieved high-sensitivity measurement of static signals using multiple modes of the microcavity, and expanded the dynamic range to the tuning range of the tunable laser of the microcavity. However, due to the need for a tunable laser for frequency sweeping and a long sampling time, this method is difficult to apply to the measurement of time-varying signals.

[0004] Patent document CN112113923A discloses a whispering gallery mode microbubble cavity-coupled CO2 sensor and its manufacturing method. After the optical signal emitted by the amplified spontaneous emission light source is coupled into the microbubble cavity through an optical fiber taper, the optical signal is coupled with the PHMB solid film on the inner wall of the microbubble cavity to form a coupled optical signal. Then, the coupled optical signal is coupled into a spectrometer through an optical fiber taper. Since the PHMB solid film reacts with CO2 gas, the refractive index of the PHMB solid film changes, so that the position of the spectral absorption peak corresponding to the coupled optical signal received by the spectrometer shifts. Then, the corresponding CO2 gas concentration is matched from the pre-established relational database to obtain the concentration of the CO2 gas to be measured. However, this patent cannot completely solve the existing technical problems and cannot meet the requirements of the present invention. Summary of the Invention

[0005] Aiming at the defects in the prior art, the purpose of the present invention is to provide a sensing method and system for time-varying signals in a whispering gallery mode microcavity.

[0006] The sensing method for time-varying signals in a whispering gallery mode microcavity provided by the present invention includes:

[0007] Step S1: Build a sensing experimental platform for time-varying signals in a whispering gallery mode microcavity based on dual optical frequency comb spectroscopy technology;

[0008] Step S2: Turn on the dual optical frequency combs;

[0009] Step S3: Couple and sense the time-varying signal through a coupling device with the whispering gallery mode microcavity;

[0010] Step S4: In one sampling time, perform Fourier transform on the outputs of the reference path and the signal path, and extract the time-varying signal by using multiple modes of the microcavity;

[0011] Step S5: Repeat Step S4 until the measurement ends.

[0012] Preferably, the dual optical frequency combs have mutual coherence, and the two can be generated by the same optical frequency comb.

[0013] Preferably, under the action of the time-varying signal, the whispering gallery mode microcavity deforms and the refractive index changes due to the cavity material, and the corresponding microcavity modes change;

[0014] The coupling device is coupled with the whispering gallery mode microcavity to guide the propagation of the optical frequency comb and sense the change of the microcavity mode of the whispering gallery mode microcavity caused by the time-varying signal.

[0015] Preferably, the coupling device includes a prism fiber, a tapered fiber, and a lens fiber.

[0016] Preferably, the Step S4 includes:

[0017] Split the first optical frequency comb into two paths through a beam splitter: the first path light and the second path light of the first optical frequency comb; the electric fields of the two paths of light are expressed as E1(t) = ∑ n A n exp[i2πt(f 01 +nf rep1 )], where f 01 is the carrier envelope phase offset frequency of the first optical frequency comb, f rep1 is the repetition frequency of the first optical frequency comb, n is the longitudinal mode order number of the first optical frequency comb, A n is the complex amplitude of each frequency point of the first optical frequency comb, t is the time unit, and i is the imaginary unit;

[0018] The optical frequency comb two is split into two paths by a beam splitter two: the first path light of the optical frequency comb two and the second path light of the optical frequency comb two; the electric fields of the two paths of light are expressed as E2(t) = ∑ m B m e xp [i2πt(f 02 +mf rep2 )], where f 02 is the carrier envelope phase offset frequency of the optical frequency comb two, f rep2 is the repetition frequency of the optical frequency comb two, m is the longitudinal mode order number of the optical frequency comb two, and B m is the complex amplitude value of each frequency point of the optical frequency comb two;

[0019] The first path light of the optical frequency comb one and the first path light of the optical frequency comb two perform multi-heterodyne interference at the combiner one, and the beat frequency signal is detected by the photodetector one as the reference path; after multi-heterodyne interference, the spectrum of the optical frequency comb in the optical frequency range will be proportionally scaled down to the range of 0 to f rep1 / 2, and a series of comb teeth are formed on the spectrum with f0 = f 01 -f 02 ≈0 as the carrier envelope phase offset and f Δrep = f rep1 -f rep2 << f rep1 as the repetition frequency; the AC component output by the photodetector one is k is the spectral sequence;

[0020] The second path light of the optical frequency comb one passes through the coupling device and senses the change in the microcavity mode of the whispering gallery mode microcavity caused by the time-varying signal. At any sampling time T j within, different frequencies of the optical frequency comb one change due to the change in the microcavity mode at the microcavity mode α p they are in, and the output electric field is expressed as where ω c，p (T j ) is the resonant frequency of the microcavity in the p mode at this sampling time, κ0 is the intrinsic loss of the microcavity, κ e is the loss of the microcavity caused by coupling, and κ e and κ e are approximately considered to be invariant when considering the dispersion sensing mechanism;

[0021] The output of the second path light of the optical frequency comb one after passing through the coupling device and the second path light of the optical frequency comb two perform multi-heterodyne interference at the beam splitter two, and the beat frequency signal is detected by the photodetector two as the signal path; the AC component output by the photodetector two is

[0022] The photodetector 1 and the photodetector 2 are connected to the data processing module, and the data processing module performs Fourier transform on the outputs of the photodetector 1 and the photodetector 2. There is a difference, and based on this, the frequency shift ω c，p (T j ) generated by each mode of the microcavity due to the action of the time-varying signal is obtained, and then the extraction of the time-varying signal is realized.

[0023] According to the sensing system for the time-varying signal of the whispering gallery mode microcavity provided by the present invention, it includes:

[0024] Module M1: Build a sensing experimental platform for the time-varying signal of the whispering gallery mode microcavity based on the dual optical frequency comb spectroscopy technology;

[0025] Module M2: Turn on the dual optical frequency combs;

[0026] Module M3: Couple with the whispering gallery mode microcavity through a coupling device to sense the time-varying signal;

[0027] Module M4: Within one sampling time, perform Fourier transform on the outputs of the reference path and the signal path, and use multiple modes of the microcavity to extract the time-varying signal;

[0028] Module M5: Repeat to trigger Module M4 until the measurement ends.

[0029] Preferably, the dual optical frequency combs have mutual coherence, and the two can be generated by the same optical frequency comb.

[0030] Preferably, the whispering gallery mode microcavity deforms under the action of the time-varying signal and the refractive index changes due to the cavity material, and the corresponding microcavity modes change;

[0031] The coupling device is coupled with the whispering gallery mode microcavity to guide the propagation of the optical frequency comb and sense the change of the microcavity mode of the whispering gallery mode microcavity caused by the time-varying signal.

[0032] Preferably, the coupling device includes a prism fiber, a tapered fiber, and a lens fiber.

[0033] Preferably, the Module M4 includes:

[0034] Split the optical frequency comb 1 into two paths through a beam splitter: the first path light and the second path light of the optical frequency comb 1; the electric fields of the two paths of light are expressed as E1(t)=∑ n A n exp[i2πt(f 01 +nf rep1 )], where f 01 is the carrier envelope phase offset frequency of the optical frequency comb 1, f rep1is the repetition frequency of optical frequency comb one, n is the longitudinal mode order number of optical frequency comb one, A n is the complex amplitude value of each frequency point of optical frequency comb one, t is the time unit, and i is the imaginary unit;

[0035] Divide optical frequency comb two into two paths through beam splitter two: the first path light of optical frequency comb two and the second path light of optical frequency comb two; the electric fields of the two paths of light are expressed as E2(t) = ∑ m B m exp[i2πt(f 02 + mf rep2 )], where, f 02 is the carrier envelope phase offset frequency of optical frequency comb two, f rep2 is the repetition frequency of optical frequency comb two, m is the longitudinal mode order number of optical frequency comb two, B m is the complex amplitude value of each frequency point of optical frequency comb two;

[0036] The first path light of optical frequency comb one and the first path light of optical frequency comb two perform multi-heterodyne interference at beam combiner one, and the beat frequency signal is detected by photodetector one as the reference path; after multi-heterodyne interference, the spectrum of the optical frequency comb in the optical frequency range will be proportionally scaled down to the range of 0 to f rep1 / 2, forming a series of comb teeth on the spectrum with f0 = f 01 - f 02 ≈ 0 as the carrier envelope phase offset, and f Δrep = f rep1 - f rep2 << f rep1 as the repetition frequency; the AC component output by photodetector one is k is the spectral sequence;

[0037] The second path light of optical frequency comb one senses the change of the microcavity mode of the whispering gallery mode microcavity caused by the time-varying signal after passing through the coupling device. At any sampling time T j within, different frequencies of optical frequency comb one change due to the change of the microcavity mode at the microcavity mode α p where it is located, and the output electric field is expressed as where, ω c，p (T j ) is the resonant frequency of the microcavity in the p mode within this sampling time, κ0 is the intrinsic loss of the microcavity, κ e is the loss of the microcavity caused by coupling, κ e and κ e are approximately considered to be invariant when considering the dispersion sensing mechanism;

[0038] The output of the second path of light from the first optical frequency comb after passing through the coupling device and the second path of light from the second optical frequency comb undergo multi-heterodyne interference in the second beam combiner, and the beat frequency signal is detected by the second photodetector, serving as the signal path; the AC component output by the second photodetector is

[0039] The first photodetector and the second photodetector are connected to the data processing module. The data processing module performs Fourier transforms on the outputs of the first photodetector and the second photodetector, and there is a difference, and based on this, the frequency shift ω c，p (T j ) generated by each mode of the microcavity due to the action of the time-varying signal is obtained, and then the extraction of the time-varying signal is realized.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) From the perspective of the overall technology, the present invention uses multiple modes of the microcavity for sensing, and can realize real-time heterodyne detection of time-varying signals with high precision, high sensitivity and large dynamic range, expanding the application scope of microcavity sensing;

[0042] (2) From the perspective of the application scope, the present invention has a wide range of applications and can be used for time-varying signals such as refractive index, temperature, pressure, acoustic signals, etc. that can cause microcavity deformation and the photoelastic coefficient of materials;

[0043] (3) From the perspective of technology improvement, the present invention adopts the dual optical frequency comb spectroscopy technology. Since the optical frequency comb spectrum has a large coverage range, the requirement for "there are multiple modes within the tunable range of the microcavity" in the previous microcavity multi-mode sensing can be weakened; since the optical frequency comb does not require tuning and frequency sweeping, the sampling time can be greatly shortened, which is suitable for real-time sensing of time-varying signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] By reading the following detailed description of the non-limiting embodiments with reference to the accompanying drawings, other features, objects and advantages of the present invention will become more obvious:

[0045] Figure 1 It is a schematic diagram of the system structure of the present invention.

[0046] Reference Signs:

[0047] 1 First optical frequency comb 5 First beam combiner 9 Second beam combiner

[0048] 2 Second optical frequency comb 6 First photodetector 10 Second photodetector

[0049] 3 First beam splitter 7 Coupling device 11 Data processing module

[0050] 4 Second beam splitter 8 Whispering gallery mode microcavity Detailed implementation mode

[0051] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those of ordinary skill in the art can make several changes and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0052] Embodiment 1

[0053] As Figure 1 shown, the present invention provides a sensing method for time-varying signals of a whispering gallery mode microcavity based on dual optical frequency comb spectroscopy, including: Step S1: Build a sensing experimental platform for time-varying signals of a whispering gallery mode microcavity based on dual optical frequency comb spectroscopy; Step S2: Turn on optical frequency comb one and optical frequency comb two; Step S3: The coupling device is coupled with the whispering gallery mode microcavity to sense the time-varying signal; Step S4: In one sampling time, by performing Fourier transform on the outputs of the reference path and the signal path, realize the extraction of the time-varying signal using multiple modes of the microcavity; Step S5: Repeat Step S4 until the measurement ends.

[0054] Building a sensing experimental platform for time-varying signals of a whispering gallery mode microcavity based on dual optical frequency comb spectroscopy in Step S1 includes: optical frequency comb one 1, optical frequency comb two 2, beam splitter one 3, beam splitter two 4, combiner one 5, photodetector one 6, coupling device 7, whispering gallery mode microcavity 8, combiner two 9, photodetector two 10, data processing module 11.

[0055] In Step S2, optical frequency comb one and optical frequency comb two are mutually coherent. Optionally, the two can be generated by the same optical frequency comb.

[0056] In Step S3, the coupling device is coupled with the whispering gallery mode microcavity to sense the time-varying signal. The whispering gallery mode microcavity 8 will deform and the refractive index will change due to the cavity material under the action of the time-varying signal; correspondingly, the microcavity mode will change. The coupling device 7 is coupled with the whispering gallery mode microcavity 8 to guide the propagation of the optical frequency comb and sense the change of the microcavity mode of the whispering gallery mode microcavity caused by the time-varying signal. Optionally, the coupling device can be prism fiber, tapered fiber, or lens fiber.

[0057] The specific implementation process of Step S4 is as follows:

[0058] The optical frequency comb one 1 is divided into two paths by the beam splitter one 3: the first path light of the optical frequency comb one and the second path light of the optical frequency comb one; the electric fields of the two paths of light can be expressed as E1(t) = ∑ n A nexp[i2πt(f 01 +nf rep1 )]. Where f 01 is the carrier - envelope phase offset frequency of the first optical frequency comb, f rep1 is the repetition frequency of the first optical frequency comb, n is the longitudinal mode order number of the first optical frequency comb, and A n is the complex amplitude of each frequency point of the first optical frequency comb.

[0059] The second optical frequency comb 2 is split into two paths by a beam splitter 4: the first path light of the second optical frequency comb and the second path light of the second optical frequency comb; the electric fields of the two paths of light can be expressed as E2(t) = ∑ m B m exp[i2πt(f 02 +mf rep2 )]. Where f 02 is the carrier - envelope phase offset frequency of the second optical frequency comb, f rep2 is the repetition frequency of the second optical frequency comb, m is the longitudinal mode order number of the second optical frequency comb, and B m is the complex amplitude of each frequency point of the second optical frequency comb.

[0060] The first path light of the first optical frequency comb and the first path light of the second optical frequency comb perform multi - heterodyne interference at a combiner 5, and the beat signal is detected by a photodetector 1 as the reference path. After multi - heterodyne interference, the spectrum of the optical frequency comb in the optical frequency range will be scaled proportionally to the range from 0 to f rep1 / 2, and a series of comb teeth with a carrier - envelope phase offset of f0 = f 01 - f 02 ≈0 and a repetition frequency of f Δrep = f rep1 - f rep2 << f rep1 are formed in the frequency spectrum. The AC component output by the photodetector 1 is

[0061] The second path light of the first optical frequency comb senses the change in the micro - cavity mode of the whispering - gallery - mode micro - cavity 8 caused by the time - varying signal after passing through a coupling device 7. At any sampling time T j within, the different frequencies of the first optical frequency comb will change due to the change in the micro - cavity mode in their respective micro - cavity modes, and the output electric field can be expressed as where ω c，p (T j ) is the resonant frequency of the micro - cavity in the p - mode at this sampling time, κ0 is the intrinsic loss of the micro - cavity, κ e is the loss of the micro - cavity caused by coupling, and κ e and κ e can be approximately considered to be invariant when considering the dispersion sensing mechanism.

[0062] The output of the second optical path of optical frequency comb 1 after passing through the coupling device and the second optical path of optical frequency comb 2 perform multi-heterodyne interference in beam combiner 9, and the beat frequency signal is detected by photodetector 2, serving as the signal path. The AC component output by photodetector 2 is

[0063] The photodetector 1 6 and photodetector 2 10 are connected to the data processing module 11. The data processing module 11 performs Fourier transforms on the outputs of photodetector 1 and photodetector 2. There is a difference between them. Based on this, the frequency shift ω c，p (T j ) generated by each mode of the microcavity due to the action of the time-varying signal can be obtained, and then the extraction of the time-varying signal is realized.

[0064] From the perspective of the overall technology, the present invention adopts the dual optical comb spectroscopy technology. Since the optical frequency comb spectrum has a large coverage range, the requirement for "there are multiple modes within the tunable range" of the microcavity in the previous multi-mode microcavity sensing can be weakened; since the optical frequency comb does not require tuning and frequency sweeping, the sampling time can be greatly shortened, which is suitable for real-time sensing of time-varying signals.

[0065] Embodiment 2

[0066] The present invention also provides a sensing system for time-varying signals of a whispering gallery mode microcavity based on the dual optical comb spectroscopy technology. The sensing system for time-varying signals of a whispering gallery mode microcavity based on the dual optical comb spectroscopy technology can be realized by executing the process steps of the sensing method for time-varying signals of a whispering gallery mode microcavity based on the dual optical comb spectroscopy technology. That is, those skilled in the art can understand the optimal phase compensation method based on the weak measurement technology of light intensity detection as the preferred implementation manner of the optimal phase compensation system based on the weak measurement technology of light intensity detection.

[0067] A sensing system for time-varying signals of a whispering gallery mode microcavity based on the dual optical comb spectroscopy technology provided by the present invention, as Figure 1 shown, includes: optical frequency comb 1, optical frequency comb 2, beam splitter 1 3, beam splitter 2 4, beam combiner 1 5, photodetector 1 6, coupling device 7, whispering gallery mode microcavity 8, beam combiner 2 9, photodetector 2 10, data processing module 11.

[0068] The optical frequency comb 1 and optical frequency comb 2 have mutual coherence, and the two can be generated by the same optical frequency comb.

[0069] The whispering gallery mode microcavity 8 will deform and the refractive index will change due to the cavity material under the action of a time-varying signal; correspondingly, the microcavity mode will change. The coupling device 7 is coupled with the whispering gallery mode microcavity 8 to guide the propagation of the optical frequency comb and sense the change in the microcavity mode of the whispering gallery mode microcavity caused by the time-varying signal. The coupling device can be a prism fiber, a tapered fiber, or a lens fiber.

[0070] The implementation process is as follows:

[0071] The first optical frequency comb 1 is split into two paths by the first beam splitter 3: the first path light of the first optical frequency comb and the second path light of the first optical frequency comb; the electric fields of the two paths of light can be expressed as E1(t) = ∑ n A n exp[i2πt(f 01 +nf rep1 )].

[0072] The second optical frequency comb 2 is split into two paths by the second beam splitter 4: the first path light of the second optical frequency comb and the second path light of the second optical frequency comb. The electric fields of the two paths of light can be expressed as E2(t) = ∑ m B m exp[i2πt(f 02 +mf rep2 )].

[0073] The first path light of the first optical frequency comb and the first path light of the second optical frequency comb perform multi-heterodyne interference at the first combiner 5, and the beat frequency signal is detected by the first photodetector 6 as the reference path. The AC component output by the first photodetector is

[0074] The second path light of the first optical frequency comb senses the change in the microcavity mode of the whispering gallery mode microcavity 8 after passing through the coupling device 7, and outputs and performs multi-heterodyne interference with the second path light of the second optical frequency comb at the second combiner 9. The beat frequency signal is detected by the second photodetector 10 as the signal path. The output electric field of the second path light of the first optical frequency comb after passing through the coupling device can be expressed as The AC component output by the second photodetector is

[0075] The first photodetector 6 and the second photodetector 10 are connected to the data processing module 11. The data processing module 11 performs Fourier transforms on the outputs of the first photodetector and the second photodetector. There is a difference between them. By comparing the intensity changes in their spectra, the frequency shift ω c，p (T j ) of each mode of the microcavity generated by the time-varying signal within the sampling time is obtained, and thus the extraction of the time-varying signal is realized.

[0076] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0077] As known to those skilled in the art, in addition to implementing the systems, devices, and their respective modules provided by the present invention in the form of pure computer-readable program code, the method steps can be logically programmed to enable the systems, devices, and their respective modules provided by the present invention to be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers, etc. to achieve the same program. Therefore, the systems, devices, and their respective modules provided by the present invention can be regarded as a kind of hardware component, and the modules included therein for implementing various programs can also be regarded as the structures within the hardware component; the modules for implementing various functions can also be regarded as either software programs for implementing the methods or the structures within the hardware component.

[0078] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Without conflict, the embodiments of the present application and the features in the embodiments can be arbitrarily combined with each other.

Claims

1. A sensing method for time-varying signals in a whispering gallery mode microcavity, characterized in that, Including: Step S1: Build a sensing experimental platform for the time-varying signal of the whispering-gallery mode microcavity based on dual-comb spectroscopy technology; Step S2: Turn on the dual optical frequency combs; Step S3: Couple and sense the time-varying signal through a coupling device with the whispering-gallery mode microcavity; Step S4: In one sampling time, perform Fourier transform on the outputs of the reference path and the signal path, and use multiple modes of the microcavity to extract the time-varying signal; Step S5: Repeat Step S4 until the measurement ends.

2. The sensing method for the time-varying signal of the whispering gallery mode microcavity according to claim 1, wherein The dual optical frequency combs have mutual coherence, and the two can be generated by the same optical frequency comb.

3. The sensing method for the time-varying signal of the whispering gallery mode microcavity according to claim 1, characterized in that Under the action of the time-varying signal, the whispering-gallery mode microcavity deforms and the refractive index changes due to the cavity material, and the corresponding microcavity modes change; The coupling device is coupled with the whispering-gallery mode microcavity to guide the propagation of the optical frequency comb and sense the change of the microcavity mode of the whispering-gallery mode microcavity caused by the time-varying signal.

4. The method for sensing a time-varying signal of a whispering gallery mode microcavity according to claim 1, characterized in that, The coupling device includes prism fiber, tapered fiber and lens fiber.

5. The sensing method for the time-varying signal of the whispering gallery mode microcavity according to claim 1, wherein The said Step S4 includes: The optical frequency comb 1 is split into two paths by a beam splitter: the first path light of the optical frequency comb 1 and the second path light of the optical frequency comb 1; the electric fields of the two paths of light are expressed as E1(t) = ∑ n A n exp[i2πt(f 01 +nf rep1 )], where f 01 is the carrier envelope phase offset frequency of the optical frequency comb 1, f rep1 is the repetition frequency of the optical frequency comb 1, n is the longitudinal mode order number of the optical frequency comb 1, A n is the complex amplitude value of each frequency point of the optical frequency comb 1, t is the time unit, and i is the imaginary unit; The optical frequency comb two is split into two paths by the beam splitter two: the first path light of the optical frequency comb two and the second path light of the optical frequency comb two; the electric fields of the two paths of light are expressed as E2(t) = ∑ m B m exp[i2πt(f 02 +mf rep2 )], where f 02 is the carrier envelope phase offset frequency of the optical frequency comb two, f rep2 is the repetition frequency of the optical frequency comb two, m is the longitudinal mode order number of the optical frequency comb two, and B m is the complex amplitude value of each frequency point of the optical frequency comb two; The first light beam of optical frequency comb 1 and the first light beam of optical frequency comb 2 undergo multi-heterodyne interference in beam combiner 1, and the beat frequency signal is detected by photodetector 1 as the reference path; after multi-heterodyne interference, the spectrum of the optical frequency comb in the optical frequency range will be proportionally scaled down to the range from 0 to f rep1 / 2, forming a series of comb teeth on the frequency spectrum with f0 = f 01 -f 02 ≈0 as the carrier envelope phase offset, with f Δrep = f rep1 -f rep2 << f rep1 as the repetition frequency; the AC component output by photodetector 1 is k is the spectral sequence; The second path of light from optical frequency comb 1 senses the change in the microcavity mode of the whispering gallery mode microcavity caused by the time-varying signal after passing through the coupling device. At any sampling time T j within, different frequencies of optical frequency comb 1 change due to the change in the microcavity mode in the microcavity mode α p they are in, and the output electric field is expressed as where ω c，p (T j ) is the resonant frequency of the microcavity in the p mode within this sampling time, κ0 is the intrinsic loss of the microcavity, and κ e is the loss of the microcavity caused by coupling, and κ e and κ e are approximately considered to be invariant when considering the dispersion sensing mechanism; The output of the second optical path of optical frequency comb 1 after passing through the coupling device and the second optical path of optical frequency comb 2 perform multi-heterodyne interference in beam combiner 2, and the beat frequency signal is detected by photodetector 2 as the signal path; the AC component output by photodetector 2 is The first photodetector and the second photodetector are connected to the data processing module. The data processing module performs Fourier transform on the outputs of the first photodetector and the second photodetector. There is a difference in their spectra , and based on this, the frequency shift ω c，p (T j ) generated by the time-varying signal for each mode of the microcavity is obtained, and then the extraction of the time-varying signal is realized.

6. A sensing system for time-varying signals in a whispering gallery mode microcavity, characterized in that, Including: Module M1: Build a sensing experimental platform for the time-varying signal of the whispering-gallery mode microcavity based on dual-comb spectroscopy technology; Module M2: Turn on the dual optical frequency combs; Module M3: Couple and sense the time-varying signal through a coupling device with the whispering-gallery mode microcavity; Module M4: In one sampling time, perform Fourier transform on the outputs of the reference path and the signal path, and use multiple modes of the microcavity to extract the time-varying signal; Module M5: Repeat triggering Module M4 until the measurement ends.

7. The sensing system for the time-varying signal of the whispering gallery mode microcavity according to claim 6, wherein The dual optical frequency combs have mutual coherence, and the two can be generated by the same optical frequency comb.

8. The sensing system for time-varying signals of a whispering gallery mode microcavity according to claim 6, characterized in that, Under the action of the time-varying signal, the whispering-gallery mode microcavity deforms and the refractive index changes due to the cavity material, and the corresponding microcavity modes change; The coupling device is coupled with the whispering-gallery mode microcavity to guide the propagation of the optical frequency comb and sense the change of the microcavity mode of the whispering-gallery mode microcavity caused by the time-varying signal.

9. The sensing system for the time-varying signal of the whispering gallery mode microcavity according to claim 6, characterized in that, The coupling device includes prism fiber, tapered fiber and lens fiber.

10. The sensing system for time-varying signals of a whispering gallery mode microcavity according to claim 6, wherein The said Module M4 includes: The optical frequency comb 1 is split into two paths by a beam splitter: the first path light of the optical frequency comb 1 and the second path light of the optical frequency comb 1; the electric fields of the two paths of light are expressed as E1(t) = ∑ n A n exp[i2πt(f 01 +nf rep1 )], where f 01 is the carrier envelope phase offset frequency of the optical frequency comb 1, f rep1 is the repetition frequency of the optical frequency comb 1, n is the longitudinal mode order number of the optical frequency comb 1, A n is the complex amplitude value of each frequency point of the optical frequency comb 1, t is the time unit, and i is the imaginary unit; The optical frequency comb two is split into two paths by the beam splitter two: the first path light of the optical frequency comb two and the second path light of the optical frequency comb two; the electric fields of the two paths of light are expressed as E2(t) = ∑ m B m exp[i2πt(f 02 +mf rep2 )], where f 02 is the carrier envelope phase offset frequency of the optical frequency comb two, f rep2 is the repetition frequency of the optical frequency comb two, m is the longitudinal mode order number of the optical frequency comb two, and B m is the complex amplitude value of each frequency point of the optical frequency comb two; The first light of optical frequency comb 1 and the first light of optical frequency comb 2 perform multi-heterodyne interference at beam combiner 1, and the beat frequency signal is detected by photodetector 1 as the reference path; after multi-heterodyne interference, the spectrum of the optical frequency comb in the optical frequency range will be proportionally scaled down to the range of 0 to f rep1 / 2, forming a series of comb teeth on the frequency spectrum with f0 = f 01 -f 02 ≈0 as the carrier envelope phase offset, with f Δrep = f rep1 -f rep2 << f rep1 as the repetition frequency; the AC component output by photodetector 1 is where k is the spectral sequence; The second path of light from optical frequency comb 1, after passing through the coupling device, senses the change in the microcavity mode of the whispering gallery mode microcavity caused by the time-varying signal. At any sampling time T j within, different frequencies of optical frequency comb 1 change due to the change in the microcavity mode in the microcavity mode α p under, and the output electric field is expressed as where ω c，p (T j ) is the resonant frequency of the microcavity in the p mode within this sampling time, κ0 is the intrinsic loss of the microcavity, and κ e is the loss of the microcavity caused by coupling. κ e and κ e are approximately considered to be invariant when considering the dispersion sensing mechanism; The output of the second optical path of optical frequency comb one after passing through the coupling device and the second optical path of optical frequency comb two perform multi-heterodyne interference in beam combiner two, and the beat frequency signal is detected by photodetector two, serving as the signal path; the AC component output by photodetector two is The first photodetector and the second photodetector are connected to the data processing module. The data processing module performs Fourier transform on the outputs of the first photodetector and the second photodetector. There is a difference in their spectra , and based on this, the frequency shift ω c，p (T j ) generated by the time-varying signal for each mode of the microcavity is obtained, and then the extraction of the time-varying signal is realized.

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