Displacement system based on sausage cavity and displacement sensing method thereof

Abstract

The invention relates to the technical field of optical sensing, in particular to a displacement system based on a sausage cavity and a displacement sensing method thereof.The system comprises a computer, a laser, a polarization controller, a displacement sensing microcavity, an optical fiber waveguide, a photoelectric detector and a displacement device.The displacement sensing microcavity comprises a first convergence section, a straight section and a second convergence section; the large-diameter end of the first convergence section and the large-diameter end of the second convergence section are connected with the two ends of the straight section respectively. The method comprises the following steps: starting the displacement device to generate relative displacement between the displacement sensing microcavity and the optical fiber waveguide; when the displacement sensing microcavity generates n times of displacement, n corresponding resonance spectrums are obtained at the output end of the optical fiber waveguide; and inputting the obtained resonance spectrum data into a computer, and monitoring the displacement condition of the displacement sensing microcavity by using the transmittance change of the resonance mode by the computer, thereby realizing the displacement sensing based on the displacement sensing microcavity. The device is convenient to use and can realize high-precision displacement measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of optical sensing, and more specifically, to a sausage cavity-based displacement system and a displacement sensing method thereof. Background Art

[0002] In recent years, whispering gallery mode microcavities have attracted extensive attention in the fields of pressure sensing, temperature sensing, chemical gas concentration detection, single nanoparticle detection, and displacement sensing due to their high sensitivity and small size. Their ultra-high quality factor (Q value) and extremely small mode volume greatly enhance the interaction between light and matter, making the whispering gallery mode microcavity extremely sensitive to changes in the external environment. By monitoring the changes in the resonant mode caused by displacement, high-precision displacement sensing can be achieved.

[0003] At present, the existing technologies for displacement sensing based on optical microcavities disclose displacement sensing systems based on double-chain SNAP structure microcavity arrays, and displacement sensing systems and displacement prediction methods based on SNAP microcavities. The core components of these two types of displacement sensing technologies are multiple SNAP cavity arrays or symmetrical arrangements. SNAP cavity is a photonic device that works based on the change of effective radius. By changing the effective radius, the light field can be regulated. However, the axial range of a single SNAP cavity is small, usually a few hundred microns, and the measurement range is greatly limited; while the use of multiple SNAP cavity arrays or symmetrical arrangements leads to complex structures and high processing difficulties. In the sensing technology based on optical microcavities, the sensing accuracy is largely affected by the number of resonance peaks. As the number of resonance peaks increases, the sensor can use more resonance points for displacement measurement. In practical applications, the scanning range of the laser during fine scanning is limited. When the SNAP cavity is coupled with the optical fiber, it is impossible to scan enough resonance peaks, which will greatly limit the accuracy of displacement sensing based on the SNAP cavity. Summary of the invention

[0004] The purpose of the present invention is to overcome the disadvantage of limited precision of SNAP cavity displacement sensing in the prior art, and to provide a displacement system based on sausage cavity and a displacement sensing method thereof, which are easy to use and can achieve high-precision displacement measurement.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] Provided is a sausage cavity-based displacement system, comprising a computer, a laser, and a polarization controller that are sequentially communicatively connected, and also comprising 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, and 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 sausage cavity-based displacement system. The first convergent section, the straight section, and the second convergent section constitute the sausage cavity. The setting 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 cone section or a truncated cone section, the second convergent section is a cone section or a truncated cone section, the top angle of the cone section or the truncated cone 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 the critical coupling state, the light waves meeting the resonance condition are effectively confined in the displacement sensing microcavity, and the highest coupling efficiency can be achieved.

[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 um.

[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 into the optical fiber waveguide after being regulated by the polarization controller; when the mode field of the displacement sensing microcavity coincides with the mode field of the light wave distributed outside the optical fiber waveguide, the light wave that meets the phase matching condition will generate resonance in the displacement sensing microcavity and form a resonant light wave signal, while the light wave that does not meet 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 and process the output signals of the output end of the optical fiber waveguide under different displacements; when the displacement sensing microcavity generates n displacements, n corresponding resonance spectra will be obtained at the output end of the optical fiber waveguide;

[0016] S3. The obtained resonance spectrum data is input into the computer, and the computer uses the transmittance change of the resonance mode to monitor the displacement of the displacement sensing microcavity, thereby realizing displacement sensing based on the displacement sensing microcavity.

[0017] Furthermore, in step S1, when the light wave is coupled into the displacement sensing microcavity, it will propagate around the axis in a spiral shape; the first convergent segment and the second convergent segment act as a barrier to the spiral mode, confining the light wave between the first convergent segment and the second convergent segment, and the light wave that meets the phase condition can excite a steady-state whispering gallery mode, forming a resonance spectrum with dense resonance peaks.

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

[0019] Furthermore, before step S1, it also includes the preparation of the displacement sensing microcavity: fine processing is performed on both ends of the single-mode optical fiber by electrode discharge of a fiber fusion machine or a carbon dioxide laser to form the first convergence section and the second convergence section; the straight section is trimmed by weak discharge technology until the transmittance of the straight section is greater than or equal to 50%.

[0020] The present invention discloses a displacement system based on a sausage cavity and a displacement sensing method thereof. The light wave output from a laser is input into an optical fiber waveguide after being regulated by a polarization controller. The light wave distributed outside the optical fiber waveguide exists in the form of an evanescent field. When the mode field of a displacement sensing microcavity coincides with the mode field of the light wave existing in the form of an evanescent field, the light wave satisfying the phase matching condition will generate a resonance phenomenon in the displacement sensing microcavity and form a resonant light wave signal, while the light wave not satisfying the condition will return from the displacement sensing microcavity to the optical fiber waveguide and propagate to a photoelectric detector. The photoelectric detector converts the collected light wave signal into an electrical signal and sends it to a computer for further processing to obtain a resonance spectrum. By using multiple resonance peaks at the same time, the displacement signal can be more accurately fitted and analyzed, thereby improving the measurement accuracy.

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

[0022] The present invention is a displacement system based on a sausage cavity and a displacement sensing method thereof. The sausage cavity is formed by the arrangement of a first convergent section, a straight section and a second convergent section. The arrangement of the sausage cavity can expand the axial measurement range of a 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. In the displacement sensing method, a light wave output from a laser is input into an optical fiber waveguide after being regulated by a polarization controller. The light wave distributed outside the optical fiber waveguide exists in the form of an evanescent field. When the mode field of the displacement sensing microcavity 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 will generate a resonance phenomenon in the displacement sensing microcavity and form a resonance light wave signal, while the light wave that does not meet the condition will return from the displacement sensing microcavity to the optical fiber waveguide and propagate to a photoelectric detector. The photoelectric detector converts the collected light wave signal into an electrical signal and sends it to a computer for further processing to obtain a resonance spectrum. By using multiple resonance peaks at the same time, the displacement signal can be more accurately fitted and analyzed, thereby improving the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a sausage cavity-based displacement system of the present invention;

[0024] Figure 2 It is a schematic diagram of the structure of the displacement sensing microcavity of the present invention;

[0025] Figure 3 A schematic diagram of the positions of the displacement sensing microcavity and the optical fiber waveguide from a top-down perspective of the present invention;

[0026] Figure 4 A schematic diagram of the positions of the displacement sensing microcavity and the optical fiber waveguide of the present invention at the main viewing angle;

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

[0028] Figure 6 It is a flow chart of a third embodiment of a displacement sensing method applied to a sausage cavity-based displacement system of the present invention;

[0029] Figure 7 It is a schematic diagram of the resonance spectrum when the optical fiber waveguide of the present invention is coupled with the sausage cavity;

[0030] Figure 8 Schematic diagram of the resonance spectrum when the optical fiber waveguide is coupled with the SNAP cavity;

[0031] Fig. 9 It is a schematic diagram of the transmittance change of the resonance mode when the sausage cavity of the present invention is displaced from 0um to 1um;

[0032] Fig.10 It is a schematic diagram of the transmittance change of the resonance mode when the sausage cavity of the present invention is displaced from 1um to 2um;

[0033] Fig.11 Schematic diagram of the prediction error when using the SNAP cavity for displacement sensing;

[0034] Fig.12 This is a schematic diagram of the prediction error when the sausage cavity is used for displacement sensing in the present invention.

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

[0036] The present invention is further described below in conjunction with specific implementation methods. The accompanying drawings are only used for exemplary descriptions and are only schematic diagrams, not actual drawings, and cannot be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0037] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0038] It should be understood by those skilled in the art that the embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention may 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 "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatuses.

[0040] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0041] Embodiment 1

[0042] like Figures 1 to 4The first embodiment of the sausage cavity-based displacement system of the present invention is shown, which includes a computer 100, a laser 200, and a polarization controller 300 that are sequentially connected in communication, and also includes a displacement sensing microcavity 400, an optical fiber waveguide 500, a photodetector 600, and a displacement device 700. The polarization controller 300 is connected in communication with the photodetector 600 through the optical fiber waveguide 500, and the output end of the photodetector 600 is connected in communication with the data input port of the computer 100; the displacement sensing microcavity 400 is connected to the moving end of the displacement device 700. , the displacement sensing microcavity 400 is coupled with the optical fiber waveguide 500; wherein, the displacement sensing microcavity 400 includes a first convergent section 410, a straight section 420, and a second convergent section 430, and 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, so that the cross-sectional area of ​​the first convergent 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 convergent 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 includes a first convergent section 410, a straight section 420, and a second convergent section 430, forming a sausage cavity. In this embodiment, the sausage cavity formed by the first convergent section 410, the straight section 420, and the second convergent section 430 can expand the axial measurement range of the displacement sensing microcavity 400, 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. In this embodiment, the laser 200 is a tunable laser that can be used to adjust the polarization state of the light wave.

[0044] like Figure 1 to Figure 2 As shown, the first convergent section 410 is a cone section or a truncated cone section, and the second convergent section 430 is a cone section or a truncated cone section, and the apex angle of the cone section or the truncated cone section is a; in this embodiment, the first convergent section 410 and the second convergent section 430 are both truncated cone sections, and the setting of the truncated cone section can facilitate the processing of the displacement sensing microcavity 400, and a is 10-60°. The setting of this angle can weaken the nonlinear effect while maintaining its sensing sensitivity requirements, and avoid the reduction of measurement accuracy. In this embodiment, the length of the straight section 420 is 0.2-10mm, and the straight section 420 is a cylindrical structure, and the radius of the cylindrical structure is 62.5um; the size setting of the straight section 420 can effectively excite the echo gallery mode, the signal resolution can meet the use requirements, and has a certain sensing range, can reduce the loss of light waves propagating in the displacement sensing microcavity 400, avoid the reduction of signal strength, and can 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 convergence section 410 or the second convergence 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 condition are effectively bound in the displacement sensing microcavity, and the highest coupling efficiency can be achieved. 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, and the diameter of the tapered optical fiber at the thinnest part is 1 to 2 um. 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 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.

[0047] The working principle of a sausage cavity-based displacement system in 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 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 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] Embodiment 2

[0050] like Figure 5 The first embodiment of a displacement sensing method of the present invention is shown, 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 input into the optical fiber waveguide 500; the light wave distributed outside the optical fiber waveguide 500 exists in the form of evanescent field. When the mode field of the sausage cavity coincides with the mode field of the light wave existing in the form of evanescent field, the light wave that meets the phase matching condition will couple into the sausage cavity and form a stable standing wave in the sausage cavity, and generate a resonance phenomenon and form a resonant light wave signal, while the light wave that does not meet the 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. Start the displacement device 700 to generate relative displacement between the displacement sensing microcavity 400 and the optical fiber waveguide 500; during the movement, collect the output signal of the output end of the optical fiber waveguide 500 under different displacements and process it; each time the displacement sensing microcavity 400 generates a displacement, the light wave signal collected at the output end of the optical fiber waveguide 500 will change accordingly; when the displacement sensing microcavity 400 generates n displacements, n corresponding resonance spectra will be 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, when the light wave is coupled into the sausage cavity, it propagates around the axis in a spiral shape; the first convergent section 410 and the second convergent section 430 act as a barrier to the spiral mode, limiting the light wave between the first convergent section 410 and the second convergent section 430, limiting the axial propagation range of the light wave, and the light wave is located in the straight section 420. The light wave that meets the phase condition can excite the steady-state whispering gallery mode and form a resonance spectrum with dense resonance peaks. In this embodiment, the operating wavelength of the laser 200 is around 1350nm and the line width is 300kHz.

[0056] Embodiment 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 moving end of the horizontal displacement component is connected to the fixed end of the vertical displacement component, and the moving 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 prior art, and can be a screw nut component or other components that can achieve displacement, which will not be repeated here.

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

[0059] The vertical distance between the displacement sensing microcavity 400 and the optical fiber waveguide 500 is adjusted by the vertical displacement component, so that the displacement sensing microcavity 400 and the optical fiber waveguide 500 are in a critical coupling state. Specifically, when the distance between the sausage cavity and the optical fiber waveguide 500 changes, the output resonance spectrum will change as a whole, that is, the transmittance increases or decreases as a whole. The computer 100 can monitor this change to enable the displacement device 700 to adjust the distance between the sausage cavity and the optical fiber waveguide 500 to achieve a critical coupling state.

[0060] Embodiment 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 also 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 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 prior to the steps described in the third embodiment. Figure 6 shown.

[0064] like Figure 7 FIG. 2 is a schematic diagram of the output resonance spectrum of the optical fiber waveguide 500 when the output wavelength of the laser 200 is 1351.8 nm to 1352.8 nm and when the fiber waveguide 500 is coupled with the sausage cavity at a certain position; Figure 8 The figure shows the output resonance spectrum of the optical fiber waveguide 500 when the output wavelength of the laser 200 is 1351.8nm to 1352.8nm and the SNAP cavity is coupled at a certain position. Figure 7 as well as Figure 8 It can be seen that the resonance peaks when the optical fiber waveguide 500 is coupled with the sausage cavity are very dense, while the resonance peaks generated when coupled with the SNAP cavity are relatively sparse.

[0065] like Fig. 9 and Fig.10 The figure shows the change in transmittance of a certain order resonance mode in the output resonance spectrum when the coupling position between the sausage cavity and the optical fiber waveguide 500 changes; the initial coupling position is set to 0um, and the incremental unit of the displacement is 0.5um. Fig. 9 It can be obtained that when the sausage cavity moves from 0um to 1um, the transmittance of the resonance mode changes; Fig.10 It can be seen that when the sausage cavity moves further from 1um to 2um, the transmittance of the resonance mode changes. During the entire process of the sausage cavity moving from 0um to 2um, five sets of resonance spectrum data can be collected. After analysis and processing, it can be observed that with the displacement of the sausage cavity, the transmittance of the resonance peak has changed significantly; it should be noted that Fig. 9 , Fig.10 To show the partial displacement changes.

[0066] like Fig.11 and Fig.12 The figure shows the prediction error when using the SNAP cavity and sausage cavity for displacement sensing. The acquisition range is 200um and the interval is 1um. The acquired data is imported into a one-dimensional convolutional neural network for training to obtain the prediction error. Fig.11 It can be seen that the maximum prediction error using the SNAP cavity can reach about 10um; Fig.12 It can be seen that the maximum prediction error using the sausage cavity is only about 3um, which greatly improves the accuracy.

[0067] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

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 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 connected in communication with the photodetector (600) through the optical fiber waveguide (500), and the photodetector (600) is connected in communication with 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 connected to the two ends of the straight section (420) respectively.

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 truncated cone section, and the second convergent section (430) is a cone section or a truncated cone section, and the apex angle of the cone section or the truncated cone section is 10 to 60 degrees; the length of the straight section (420) is 0.2 to 10 mm, and the straight section (420) is a cylindrical structure, and the radius of the cylindrical structure is 62.5 um.

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 um.

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 input into the optical fiber waveguide (500) after being regulated by the polarization controller (300); 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 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; S2. activating the displacement device (700) to generate a 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, characterized in that: 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, characterized in that: The displacement device (700) further comprises a vertical displacement component; and before step S1, further comprises: adjusting the distance between the displacement sensing microcavity (400) and the optical fiber waveguide (500) in the vertical direction by means of 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, characterized in that: Before step S1, the method also includes the preparation of the displacement sensing microcavity (400): fine processing is performed on both 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); 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%.

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