A sausage cavity-based displacement system and a displacement sensing method thereof

Abstract

The present application relates to the technical field of optical sensing, and more particularly to a displacement system based on sausage cavity and a displacement sensing method thereof, the system comprising a computer, a laser, a polarization controller, a displacement sensing microcavity, a fiber waveguide, a photodetector and a displacement device, the displacement sensing microcavity comprising a first converging section, a straight section and a second converging section, the large-diameter ends of the first and second converging sections being connected to the two ends of the straight section respectively. The method comprises: starting the displacement device to cause relative displacement between the displacement sensing microcavity and the fiber waveguide; when the displacement sensing microcavity is displaced n times, n corresponding resonance spectra are obtained at the output end of the fiber waveguide; and the obtained resonance spectrum data is input into the computer, which monitors the displacement of the displacement sensing microcavity by using the transmittance change of the resonance mode, thereby realizing displacement sensing based on the displacement sensing microcavity. The present application is convenient to use and can realize high-precision displacement measurement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical sensing, and more particularly to a displacement system based on a sausage cavity and a displacement sensing method thereof. BACKGROUND

[0002] In recent years, an echo-wall mode microcavity has been widely concerned in the fields of pressure sensing, temperature sensing, chemical gas concentration detection, single nanoparticle detection and displacement sensing due to its high sensitivity and small volume. The super-high quality factor (Q value) and the extremely small mode volume of the echo-wall mode microcavity greatly enhance the interaction between light and matter, making the echo-wall mode microcavity extremely sensitive to changes in the external environment. By monitoring the resonant mode changes caused by displacement, high-precision displacement sensing can be achieved.

[0003] The existing technologies for displacement sensing based on optical microcavities include a displacement sensing system based on a double-chain SNAP structure microcavity array and a displacement sensing system and a displacement prediction method based on a SNAP microcavity. The core components of these two types of displacement sensing technologies are multiple SNAP cavity arrays or symmetrical arrangements. A SNAP cavity is a photonic device that works based on the change of effective radius, and the light field can be regulated by changing the effective radius. However, the axial range of a single SNAP cavity is small, usually a few hundred microns, and the measurement range is greatly limited. The use of multiple SNAP cavity arrays or symmetrical arrangements results in a complex structure and great difficulty in processing. In the sensing technology based on optical microcavities, the sensing precision is greatly affected by the number of resonant peaks. With the increase of the number of resonant peaks, the sensor can utilize more resonant points for displacement measurement. However, in practical applications, the scanning range of the laser is limited, and when the SNAP cavity is coupled with the optical fiber, enough resonant peaks cannot be scanned, which will greatly limit the precision of the displacement sensing based on the SNAP cavity. SUMMARY

[0004] The present application aims to overcome the limitation of the precision of the SNAP cavity displacement sensing in the prior art and provide a displacement system based on a sausage cavity and a displacement sensing method thereof, which is convenient to use and can achieve high-precision displacement measurement.

[0005] To solve the above technical problems, the technical solution adopted by the present application is as follows:

[0006] A sausage cavity-based displacement system is provided, comprising a computer, a laser, and a polarization controller that are communicatively connected in sequence; a displacement sensing microcavity, an optical fiber waveguide, a photodetector, and a displacement device, wherein the polarization controller is communicatively connected to the photodetector via the optical fiber waveguide, and the photodetector is communicatively connected to the computer; the displacement sensing microcavity is connected to the moving end of the displacement device, and the displacement sensing microcavity is coupled to the optical fiber waveguide; wherein the displacement sensing microcavity comprises a first convergent section, a straight section, and a second convergent section, wherein the large-diameter end of the first convergent section and the large-diameter end of the second convergent section are respectively connected to the two ends of the straight section.

[0007] The present invention includes a displacement system based on a sausage cavity. The arrangement of a first convergent section, a straight section, and a second convergent section constitutes the sausage cavity. The arrangement of the sausage cavity can expand the axial measurement range of the displacement sensing microcavity, so that when the scanning range is limited, the sausage cavity can generate a resonance spectrum with more resonance peaks, thereby improving the measurement accuracy and range.

[0008] Furthermore, the first convergent section is a conical section or a frustum section, the second convergent section is a conical section or a frustum section, the top angle of the conical section or the frustum section is 10 to 60°; the length of the straight section is 0.2 to 10 mm, the straight section is a cylindrical structure, and the radius of the cylindrical structure is 62.5 um.

[0009] Furthermore, the displacement sensing microcavity and the optical fiber waveguide are in a critical coupling state, in which light waves meeting the resonance condition are effectively confined in the displacement sensing microcavity, thereby achieving the highest coupling efficiency.

[0010] Furthermore, the optical fiber waveguide is a tapered optical fiber, and the diameter of the tapered optical fiber at its thinnest point is 1 to 2 μm.

[0011] Furthermore, the displacement sensing microcavity and the optical fiber waveguide are both placed horizontally, the optical fiber waveguide and the displacement sensing microcavity are arranged perpendicular to each other in the extension direction, and the displacement sensing microcavity corresponds to the thinnest position of the optical fiber waveguide.

[0012] Furthermore, the displacement sensing microcavity is a silicon oxide rod.

[0013] The present invention also provides a displacement sensing method applied to a sausage cavity-based displacement system, comprising the following steps:

[0014] S1. The light wave output from the laser is input to the optical fiber waveguide through the polarization controller; when the mode field of the displacement sensing microcavity and the mode field of the light wave distributed outside the optical fiber waveguide coincide, the light wave satisfying the phase matching condition will generate resonance phenomenon in the displacement sensing microcavity and form a resonant light wave signal, and the light wave not satisfying the condition will return from the displacement sensing microcavity to the optical fiber waveguide and propagate to the photodetector; the photodetector converts the collected light wave signal into an electrical signal and sends it to the computer for further processing to obtain a resonance spectrum;

[0015] S2. Start the displacement device to generate relative displacement between the displacement sensing microcavity and the optical fiber waveguide; during the movement, collect the output signals of the output end of the optical fiber waveguide under different displacements and process them; when the displacement sensing microcavity generates n times of displacement, n corresponding resonance spectra will be obtained at the output end of the optical fiber waveguide;

[0016] S3. Input the obtained resonance spectrum data into the computer, and the computer monitors the displacement of the displacement sensing microcavity by using the change of the transmission rate of the resonance mode, so as to realize displacement sensing based on the displacement sensing microcavity.

[0017] Further, in step S1, after the light wave is coupled into the displacement sensing microcavity, it will propagate in a spiral line around the axis; the first converging section and the second converging section act as a barrier to the spiral mode, limiting the light wave between the first converging section and the second converging section, and the light wave satisfying the phase condition can excite a stable whispering gallery mode to form a resonance spectrum with dense resonance peaks.

[0018] Further, the displacement device further comprises a vertical displacement assembly; before step S1, it further comprises: adjusting the distance between the displacement sensing microcavity and the optical fiber waveguide in the vertical direction by the vertical displacement assembly, so that the displacement sensing microcavity and the optical fiber waveguide are in a critical coupling state.

[0019] Further, before step S1, it further comprises the preparation of the displacement sensing microcavity: the two ends of the single-mode optical fiber are finely processed by electrode discharge of the optical fiber fusion splicer or carbon dioxide laser to form the first converging section and the second converging section; the straight section is trimmed by weak discharge technology until the transmission rate of the straight section is greater than or equal to 50%.

[0020] The application is a displacement system based on sausage cavity and a displacement sensing method thereof, wherein light waves output from a laser are input to a fiber waveguide after being regulated by a polarization controller; the light waves distributed outside the fiber waveguide exist in the form of evanescent field; when the mode field of the displacement sensing microcavity coincides with the mode field of the light waves existing in the form of evanescent field, the light waves satisfying the phase matching condition will generate resonance phenomenon in the displacement sensing microcavity and form resonant light wave signals, and the light waves not satisfying the condition will return from the displacement sensing microcavity to the fiber waveguide and propagate to a photodetector; the photodetector converts the collected light wave signals into electrical signals and sends them to a computer for further processing to obtain a resonance spectrum; by simultaneously using multiple resonance peaks, the displacement signal can be more accurately fitted and analyzed, and the measurement accuracy is improved.

[0021] Compared with the prior art, the application has the following beneficial effects:

[0022] The application is a displacement system based on sausage cavity and a displacement sensing method thereof, wherein a first converging section, a straight section and a second converging section are arranged to form a sausage cavity, the arrangement of the sausage cavity can expand the axial measurement range of the displacement sensing microcavity, so that in the case of limited scanning range, the sausage cavity can generate a resonance spectrum with more resonance peaks, thereby improving the measurement accuracy and range; in the displacement sensing method, light waves output from a laser are input to a fiber waveguide after being regulated by a polarization controller; the light waves distributed outside the fiber waveguide exist in the form of evanescent field; when the mode field of the displacement sensing microcavity coincides with the mode field of the light waves existing in the form of evanescent field, the light waves satisfying the phase matching condition will generate resonance phenomenon in the displacement sensing microcavity and form resonant light wave signals, and the light waves not satisfying the condition will return from the displacement sensing microcavity to the fiber waveguide and propagate to a photodetector; the photodetector converts the collected light wave signals into electrical signals and sends them to a computer for further processing to obtain a resonance spectrum; by simultaneously using multiple resonance peaks, the displacement signal can be more accurately fitted and analyzed, and the measurement accuracy is improved. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a structure schematic view of the displacement system based on sausage cavity of the application;

[0024] Figure 2 It is a structure schematic view of the displacement sensing microcavity of the application;

[0025] Figure 3 It is a position schematic view of the displacement sensing microcavity and the fiber waveguide from the top view angle of the application;

[0026] Figure 4 It is a position schematic view of the displacement sensing microcavity and the fiber waveguide from the front view angle of the application;

[0027] Figure 5 It is a flow chart of the first embodiment of the displacement sensing method applied to the displacement system based on sausage cavity of the application;

[0028] Figure 6 Flow chart of a third embodiment of a displacement sensing method applied to a displacement system based on a sausage cavity according to the present application;

[0029] Figure 7 Resonance spectrum diagram when a fiber waveguide is coupled with a sausage cavity according to the present application;

[0030] Figure 8 Resonance spectrum diagram when a fiber waveguide is coupled with a SNAP cavity;

[0031] Figure 9 Transmittance change diagram of the resonance mode when the sausage cavity is displaced from 0 um to 1 um according to the present application;

[0032] Figure 10 Transmittance change diagram of the resonance mode when the sausage cavity is displaced from 1 um to 2 um according to the present application;

[0033] Figure 11 Prediction error diagram when displacement sensing is performed using a SNAP cavity;

[0034] Figure 12 Prediction error diagram when displacement sensing is performed using a sausage cavity according to the present application.

[0035] In the drawings: 100, computer; 200, laser; 300, polarization controller; 400, displacement sensing microcavity; 410, first converging section; 420, straight section; 430, second converging section; 440, connecting section; 500, fiber waveguide; 600, photodetector; 700, displacement device. DETAILED DESCRIPTION

[0036] The present application will be further described below in conjunction with specific embodiments. In the drawings, only exemplary illustrations are shown, and the representations are only schematic diagrams, not physical diagrams, and should not be understood as limiting the present patent; in order to better illustrate the embodiments of the present application, some components in the drawings will be omitted, enlarged or reduced, and do not represent the actual size of the product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings can be omitted.

[0037] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it is to be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right" and the like 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, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for exemplary illustration, and cannot be understood as a limitation on the present patent, and for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0038] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0039] It should be noted that the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above drawings are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device containing a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0040] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0041] Embodiment one

[0042] As Figures 1 to 4As shown is a first embodiment of a displacement system based on a sausage cavity of the application, comprising a computer 100, a laser 200, a polarization controller 300 connected in sequence, and further comprising a displacement sensing microcavity 400, a fiber waveguide 500, a photodetector 600, a displacement device 700, the polarization controller 300 being connected in communication with the photodetector 600 through the fiber waveguide 500, the output end of the photodetector 600 being connected in communication with the data input port of the computer 100; the displacement sensing microcavity 400 is connected with the moving end of the displacement device 700, and the displacement sensing microcavity 400 is coupled with the fiber waveguide 500; wherein the displacement sensing microcavity 400 comprises a first converging section 410, a straight section 420, and a second converging section 430, the large diameter end of the first converging section 410 and the large diameter end of the second converging section 430 are respectively connected with both ends of the straight section 420, so that the cross-sectional area of the first converging section 410 gradually increases from the end far away from the straight section 420 to the end close to the straight section 420, and the cross-sectional area of the second converging section 430 also gradually increases from the end far away from the straight section 420 to the end close to the straight section 420.

[0043] The displacement sensing microcavity 400 comprises the first converging section 410, the straight section 420, and the second converging section 430, which constitute a sausage cavity. In this embodiment, the sausage cavity composed of the first converging section 410, the straight section 420, and the second converging section 430 can expand the axial measurement range of the displacement sensing microcavity 400, so that in the case of limited scanning range, the sausage cavity can generate a resonance spectrum with more resonance peaks, thereby improving the measurement accuracy and range. In this embodiment, the laser 200 is a tunable laser, which can be used to adjust the polarization state of the light wave.

[0044] As shown in Figures 1 to 2 The first converging section 410 is a tapered section or a circular truncated cone section, and the second converging section 430 is a tapered section or a circular truncated cone section, and the top angle of the tapered section or the circular truncated cone section is a; in this embodiment, the first converging section 410 and the second converging section 430 are both circular truncated cone sections, and the setting of the circular truncated cone section can facilitate the processing of the displacement sensing microcavity 400, a is 10-60°, and the setting of this angle can weaken the nonlinear effect while maintaining the required sensing sensitivity, thereby avoiding a decrease in measurement accuracy. In this embodiment, the length of the straight section 420 is 0.2-10 mm, the straight section 420 is a cylindrical structure, and the radius of the cylindrical structure is 62.5 um; the size of the straight section 420 can effectively excite the whispering gallery mode, the signal resolution can meet the use requirements, and has a certain sensing range, which can reduce the loss of light wave propagation in the displacement sensing microcavity 400, avoid the decrease of signal strength, and have good mechanical stability.

[0045] In this embodiment, in order to facilitate the connection between the displacement sensing microcavity 400 and the displacement device 700, the displacement sensing microcavity 400 further includes a connecting section 440, which is connected to the first convergent section 410 or the second convergent section 430, and the connecting section 440 is fixedly connected to the moving end of the displacement device 700. Figure 2 As shown, the second convergent section 430 is fixedly connected to the connecting section 440. Specifically, the displacement sensing microcavity 400 is integrally formed and is made of a silicon oxide rod.

[0046] In this embodiment, the displacement sensing microcavity 400 and the optical fiber waveguide 500 are in a critical coupling state. In the critical coupling state, the light waves that meet the resonance conditions are effectively confined in the displacement sensing microcavity, which can achieve the highest coupling efficiency. Among them, the optical fiber waveguide 500 is a tapered optical fiber, and the optical fiber waveguide 500 has a structure with thick ends and thin middle. The diameter of the thinnest part of the tapered optical fiber is 1 to 2 μm. Figure 1 、 Figure 3 and Figure 4 As shown, the displacement sensing microcavity 400 and the optical fiber waveguide 500 are both placed horizontally, the optical fiber waveguide 500 and the displacement sensing microcavity 400 are perpendicular to each other in the extension direction, and the thinnest positions of the displacement sensing microcavity 400 and the optical fiber waveguide 500 correspond to each other.

[0047] The working principle of the sausage cavity-based displacement system of this embodiment is as follows:

[0048] The light wave output from the laser 200 is regulated by the polarization controller 300 and input into the optical fiber waveguide 500. When the mode field of the displacement sensing microcavity 400 coincides with the mode field of the light wave distributed outside the optical fiber waveguide 500, the light wave that meets the phase matching condition will resonate in the displacement sensing microcavity 400 and form a resonant light wave signal, while the light wave that does not meet the condition will return from the displacement sensing microcavity 400 to the optical fiber waveguide 500 and propagate to the photodetector 600. The photodetector 600 converts the collected light wave signal into an electrical signal and sends it to the computer 100 for further processing to obtain a resonance spectrum.

[0049] Example 2

[0050] like Figure 5 The figure shows a first embodiment of a displacement sensing method of the present invention, which is applied to the sausage cavity-based displacement system described in the first embodiment and includes the following steps:

[0051] S1. The light wave output from the laser 200 is regulated by the polarization controller 300 and then input into the optical fiber waveguide 500. The light wave distributed outside the optical fiber waveguide 500 exists in the form of an evanescent field. When the mode field of the sausage cavity coincides with the mode field of the light wave existing in the form of an evanescent field, the light wave that meets the phase matching condition is coupled into the sausage cavity and forms a stable standing wave in the sausage cavity, generating a resonance phenomenon and forming a resonant light wave signal. The light wave that does not meet the phase matching condition returns from the sausage cavity to the optical fiber waveguide 500 and propagates to the photodetector 600. The photodetector 600 converts the collected light wave signal into an electrical signal and sends it to the computer 100 for further processing to obtain a resonance spectrum.

[0052] S2. Activating the displacement device 700 to generate relative displacement between the displacement sensing microcavity 400 and the optical fiber waveguide 500; during the displacement process, the output signals from the output end of the optical fiber waveguide 500 at different displacements are collected and processed; each time the displacement sensing microcavity 400 is displaced, the light wave signal collected at the output end of the optical fiber waveguide 500 changes accordingly; when the displacement sensing microcavity 400 is displaced n times, n corresponding resonance spectra are obtained at the output end of the optical fiber waveguide 500;

[0053] S3. The obtained resonance spectrum data is input into the computer 100 . The computer 100 uses the transmittance change of the resonance mode to monitor the displacement of the displacement sensing microcavity 400 , thereby realizing displacement sensing based on the displacement sensing microcavity 400 .

[0054] The present invention can more accurately fit and analyze the displacement signal by using multiple resonance peaks simultaneously, thereby improving the measurement accuracy.

[0055] In step S1, after the lightwave is coupled into the sausage cavity, it propagates in a spiral pattern around the axis. The first and second converging sections 410, 430 act as barriers to the spiral mode, confining the lightwave between the first and second converging sections 410, 430 and limiting its axial propagation range. The lightwave is located within the straight section 420. Lightwaves that meet the phase conditions can excite steady-state whispering gallery modes, forming a resonant spectrum with dense resonant peaks. In this embodiment, the operating wavelength of the laser 200 is approximately 1350 nm, with a linewidth of 300 kHz.

[0056] Example 3

[0057] This embodiment is a second embodiment of a displacement sensing method. This embodiment is similar to the second embodiment, except that the displacement device 700 in this embodiment includes a horizontal displacement component and a vertical displacement component, wherein the movable end of the horizontal displacement component is connected to the fixed end of the vertical displacement component, and the movable end of the vertical displacement component is connected to the displacement sensing microcavity 400. The setting of the horizontal displacement component can be used to drive the displacement sensing microcavity 400 to move in the axial direction, and the setting of the vertical displacement component can be used to drive the displacement sensing microcavity 400 to move away from or close to the optical fiber waveguide 500 in the vertical direction to adjust the distance between the two. It should be noted that the horizontal displacement component and the vertical displacement component are existing technologies and can be screw nut components or other components that can achieve displacement, and will not be described in detail here.

[0058] Specifically, before step S1, the following steps are also included:

[0059] The vertical displacement assembly adjusts the vertical spacing between the displacement sensing microcavity 400 and the optical fiber waveguide 500, maintaining a critical coupling state between the displacement sensing microcavity 400 and the optical fiber waveguide 500. Specifically, when the spacing between the sausage cavity and the optical fiber waveguide 500 changes, the overall output resonance spectrum changes, resulting in an overall increase or decrease in transmittance. The computer 100 monitors these changes and enables the displacement device 700 to adjust the spacing between the sausage cavity and the optical fiber waveguide 500 to achieve a critical coupling state.

[0060] Example 4

[0061] This embodiment is a third embodiment of a displacement sensing method. This embodiment is similar to the second or third embodiment, except that, before step S1, it further includes the preparation of a displacement sensing microcavity 400:

[0062] The two ends of the single-mode optical fiber are finely processed by electrode discharge of a fiber fusion splicer or a carbon dioxide laser to form a first convergent section 410 and a second convergent section 430; the straight section 420 is partially trimmed by weak discharge technology until the transmittance of the straight section 420 is greater than or equal to 50%.

[0063] It should be noted that the preparation steps of the displacement sensing microcavity 400 are before the steps described in the third embodiment, such as Figure 6 shown.

[0064] like Figure 7 FIG. 1 is a schematic diagram of the output resonance spectrum of the optical fiber waveguide 500 when coupled with the sausage cavity at a certain position when the output wavelength of the laser 200 is 1351.8 nm to 1352.8 nm; Figure 8 The figure shows the output resonance spectrum of the laser 200 when the output wavelength is 1351.8nm to 1352.8nm and the optical fiber waveguide 500 is coupled with the SNAP cavity at a certain position. Figure 7 and Figure 8 It can be seen that the resonant peaks are very dense when the fiber waveguide 500 is coupled with the sausage cavity, and the resonant peaks are sparse when coupled with the SNAP cavity.

[0065] As Figure 9 and Figure 10 Figures 6 and 7 show the transmittance change of a certain resonant mode in the output resonant spectrum when the coupling position of the sausage cavity and the fiber waveguide 500 changes; the initial coupling position is set to 0 um, and the incremental unit of displacement is 0.5 um. Figure 9 It can be seen that the transmittance change of the resonant mode when the sausage cavity is displaced from 0 um to 1 um; from Figure 10 It can be seen that the transmittance change of the resonant mode when the sausage cavity is further displaced from 1 um to 2 um. During the entire process of displacement from 0 um to 2 um, five sets of resonant spectrum data can be collected. After analysis and processing, it can be observed that the transmittance of the resonant peak has changed significantly with the displacement of the sausage cavity; it should be noted that Figure 9 , Figure 10 Figures 8 and 9 show part of the displacement change.

[0066] As Figure 11 and Figure 12 Figures 10 and 11 show the prediction error diagrams when using the SNAP cavity and the sausage cavity for displacement sensing, respectively. The collected range is 200 um, and the interval is 1 um. The collected data is imported into a one-dimensional convolutional neural network for training to obtain the prediction error. From Figure 11 It can be seen that the maximum prediction error using the SNAP cavity is about 10 um; from Figure 12 It can be seen that the maximum prediction error using the sausage cavity is only about 3 um, greatly improving the accuracy.

[0067] In the specific content of the above specific embodiments, each technical feature can be combined in any manner without contradiction, and to make the description concise, not all possible combinations of the above technical features are described, but as long as the combination of these technical features does not exist contradiction, it should be considered as the scope of the present disclosure.

[0068] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the implementation manner of the present application. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to exhaust all the implementation manners. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A sausage cavity-based displacement system, characterized in that: The invention comprises a computer (100), a laser (200), and a polarization controller (300) which are communicatively connected in sequence, and also comprises a displacement sensing microcavity (400), an optical fiber waveguide (500), a photodetector (600), and a displacement device (700). The polarization controller (300) is communicatively connected to the photodetector (600) via the optical fiber waveguide (500), and the photodetector (600) is communicatively connected to the computer (100). The displacement sensing microcavity (400) is connected to the moving end of the displacement device (700), and the displacement sensing microcavity (400) is coupled to the optical fiber waveguide (500). The displacement sensing microcavity (400) comprises a first convergent section (410), a straight section (420), and a second convergent section (430). The large-diameter end of the first convergent section (410) and the large-diameter end of the second convergent section (430) are respectively connected to the two ends of the straight section (420).

2. The sausage cavity-based displacement system according to claim 1, characterized in that: The first convergent section (410) is a cone section or a frustum section, the second convergent section (430) is a cone section or a frustum section, the apex angle of the cone section or the frustum section is 10 to 60 degrees; the length of the straight section (420) is 0.2 to 10 mm, the straight section (420) is a cylindrical structure, and the radius of the cylindrical structure is 62.5 μm.

3. The sausage cavity-based displacement system according to claim 1, characterized in that: The displacement sensing microcavity (400) and the optical fiber waveguide (500) are in a critical coupling state.

4. The sausage cavity-based displacement system according to claim 1, characterized in that: The optical fiber waveguide (500) is a tapered optical fiber, and the diameter of the tapered optical fiber at its thinnest point is 1 to 2 μm.

5. The sausage cavity-based displacement system according to claim 4, characterized in that: The displacement sensing microcavity (400) and the optical fiber waveguide (500) are both placed horizontally, the optical fiber waveguide (500) and the displacement sensing microcavity (400) are arranged perpendicular to each other in the extension direction, and the thinnest positions of the displacement sensing microcavity (400) and the optical fiber waveguide (500) correspond to each other.

6. The sausage cavity-based displacement system according to any one of claims 1 to 5, characterized in that: The displacement sensing microcavity (400) is a silicon oxide rod.

7. A displacement sensing method applied to the sausage cavity-based displacement system according to any one of claims 1 to 6, characterized in that: The steps include: S1. The light wave output from the laser (200) is regulated by the polarization controller (300) and input into the optical fiber waveguide (500); when the mode field of the displacement sensing microcavity (400) coincides with the mode field of the light wave distributed outside the optical fiber waveguide (500), the light wave that meets the phase matching condition will generate a resonance phenomenon in the displacement sensing microcavity (400) and form a resonant light wave signal, while the light wave that does not meet the condition returns from the displacement sensing microcavity (400) to the optical fiber waveguide (500) and propagates to the photodetector (600); the photodetector (600) converts the collected light wave signal into an electrical signal and sends it to the computer (100) for further processing to obtain a resonance spectrum; S2. activating the displacement device (700) to generate relative displacement between the displacement sensing microcavity (400) and the optical fiber waveguide (500); During the movement, the output signals of the output end of the optical fiber waveguide (500) under different displacements are collected and processed; when the displacement sensing microcavity (400) generates n displacements, n corresponding resonance spectra are obtained at the output end of the optical fiber waveguide (500); S3. The obtained resonance spectrum data is input into the computer (100), and the computer (100) uses the transmittance change of the resonance mode to monitor the displacement of the displacement sensing microcavity (400), thereby realizing displacement sensing based on the displacement sensing microcavity (400).

8. The displacement sensing method according to claim 7, wherein: In step S1, after the light wave is coupled into the displacement sensing microcavity (400), it propagates in a spiral shape around the axis; the first convergent section (410) and the second convergent section (430) act as a barrier to the spiral mode, confining the light wave between the first convergent section (410) and the second convergent section (430); the light wave that meets the phase condition can excite a steady-state whispering gallery mode, forming a resonance spectrum with dense resonance peaks.

9. The displacement sensing method according to claim 7, wherein: The displacement device (700) further includes a vertical displacement component; and before step S1, further includes: adjusting the vertical distance between the displacement sensing microcavity (400) and the optical fiber waveguide (500) by using the vertical displacement component, so that the displacement sensing microcavity (400) and the optical fiber waveguide (500) are in a critical coupling state.

10. The displacement sensing method according to claim 7, wherein: Before step S1, the method further includes preparing the displacement sensing microcavity (400): finely processing the two ends of the single-mode optical fiber by electrode discharge of an optical fiber fusion splicer or a carbon dioxide laser to form the first convergent section (410) and the second convergent section (430); and trimming the straight section (420) by a weak discharge technique until the transmittance of the straight section (420) is greater than or equal to 50%.

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