阅读说明：本技术 一种基于双链式snap结构微腔阵列的位移传感系统 (Displacement sensing system based on double-chain SNAP structure microcavity array ) 是由 董永超 孙鹏辉 赵泽政 陈剑 王晗 王瑞洲 于 2020-06-10 设计创作，主要内容包括：本发明公开了一种基于双链式SNAP结构微腔阵列的位移传感系统,该位移传感系统主要包括可调谐激光器、偏振控制器、耦合波导、SNAP结构微腔阵列双链、位移装置、光电探测器、以及计算机。可调谐激光器产生扫频激光,经偏振控制器和耦合波导进入双链的SNAP结构微腔,光电探测器获取谐振谱并送入计算机处理。当微腔移动时,基于单个SNAP结构微腔的谐振谱特征实现半个SNAP结构长度的位移传感；每跨过半个SNAP结构长度,通过依次切换使用双链中的SNAP微腔产生的谐振谱,实现全范围的位移传感。该位移传感系统可实现大量程位移的高精度传感,且具有体积小、成本低和具备微结构测量的优势。(The invention discloses a displacement sensing system based on a double-chain SNAP structure microcavity array. The tunable laser generates sweep-frequency laser, the sweep-frequency laser enters the double-chain SNAP structural microcavity through the polarization controller and the coupling waveguide, and the photoelectric detector acquires a resonance spectrum and sends the resonance spectrum to the computer for processing. When the micro-cavity moves, displacement sensing of half SNAP structure length is realized based on resonance spectrum characteristics of the single SNAP structure micro-cavity; and when the length of each SNAP structure is over half, the full-range displacement sensing is realized by sequentially switching resonance spectrums generated by SNAP micro-cavities in the double chains. The displacement sensing system can realize high-precision sensing of large-range displacement, and has the advantages of small volume, low cost and microstructure measurement.)

1. A displacement sensing system based on a double-chain SNAP structure microcavity array is characterized by comprising a tunable laser, a polarization controller, a coupling waveguide, an SNAP structure microcavity array group, a displacement device, a photoelectric detector and a computer; one end of the polarization controller is connected with the tunable laser, and the other end of the polarization controller is connected with one end of the coupling waveguide; one end of the photoelectric detector is connected with the other end of the waveguide, and the other end of the photoelectric detector is connected with the computer; the coupling waveguide is provided with an emergent end and an incident end, and the emergent end and the incident end are arranged oppositely; the SNAP structure microcavity array group is arranged between the emergent end and the incident end of the coupling waveguide, so that laser is emitted from the emergent end and enters the incident end after passing through the SNAP structure microcavity array group; two ends of the SNAP structure micro-cavity array group are fixedly arranged on the displacement device; the displacement device is arranged on the mobile platform; the SNAP structure microcavity array group consists of a plurality of SNAP structure microcavity arrays which are arranged in parallel;

the tunable laser generates laser with continuously tunable wavelength and inputs the laser into a polarization controller, and the polarization controller controls the polarization state of the light wave in the optical fiber; the coupling waveguide couples the light waves in the optical fiber into the SNAP structure microcavity array group through an evanescent field; the photoelectric detector is used for converting the optical signal into an electric signal; the displacement device is used for adjusting the displacement of the SNAP structure microcavity array group relative to the coupling waveguide, so that the SNAP structure microcavity array group moves relative to the coupling waveguide, and the coupling position of the microcavity and the waveguide is changed, so as to change the Q value and the transmittance of a resonance mode in a coupling resonance spectrum; and the photoelectric detector is input into the computer for processing after measuring the resonance signal.

2. The displacement sensing system based on the double-chain type SNAP structure microcavity array according to claim 1, wherein the SNAP structure microcavity array group comprises a first SNAP structure microcavity array and a second SNAP structure microcavity array; the first SNAP structure micro-cavity array and the second SNAP structure micro-cavity array are parallel to each other, and the internal micro-cavity of the first SNAP structure micro-cavity array and the internal micro-cavity of the second SNAP structure micro-cavity array are arranged in a staggered mode.

3. The displacement sensing system based on the double-chain SNAP structure microcavity array according to claim 1, wherein the coupling waveguide is a micro-nano tapered fiber, a coupling prism, an integrated optical waveguide, a ground tilt angle fiber or a fiber grating.

4. The displacement sensing system based on the double-chain SNAP structure microcavity array according to claim 1, wherein each SNAP structure on the SNAP structure microcavity array set is a microcavity, and each SNAP structure microcavity array has the same axial length.

5. The displacement sensing system based on the double-chain SNAP structure microcavity array according to claim 1, wherein the shape of the longitudinal cross section of the SNAP structure in the SNAP structure microcavity array group is parabolic, Gaussian curve or trapezoid.

6. The displacement sensing system based on the double-chain SNAP structure microcavity array according to claim 2, wherein the first SNAP structure microcavity array and the second SNAP structure microcavity array are arranged in parallel, the distance is set to be more than 1mm, and the half SNAP structure length is staggered in the axial direction.

7. The displacement sensing system based on the double-chain SNAP structure microcavity array according to claim 2, wherein different effective radius variations are adopted between the first SNAP structure microcavity array and the second SNAP structure microcavity array, so that different resonance modes are generated to facilitate distinguishing on a resonance spectrum.

8. The displacement sensing system based on the double-chain SNAP structure microcavity array according to claim 1, wherein the coupling waveguide is always kept in contact with the SNAP structure microcavity array group during operation.

9. The displacement sensing system based on the double-chain SNAP structure microcavity array according to claim 1, wherein the SNAP structure microcavity array group is obtained by using arc discharge, carbon dioxide laser or ultraviolet light to act on an optical fiber; the axial length L range of a single microcavity of the SNAP structure microcavity array group is 0.5-1.5 mm, and the array number can be determined according to actual needs.

10. The displacement sensing system based on the double-chain SNAP structure microcavity array according to claim 1, wherein the effective radius variation of the SNAP structure microcavity array group is 10-100 nm.

Technical Field

The invention relates to the technical field of optical sensing, in particular to a displacement sensing system based on a double-chain type surface nano-scale axial photon (SNAP) structure microcavity array.

Background

In the last two decades, precision and ultra-precision machining technologies, such as ultra-precision machining tools, lithography machines and other equipment, have been developed rapidly, and fundamentally depend on the development of ultra-precision displacement measurement equipment. The ultra-precise displacement measuring equipment comprises a magnetoelectric sensor, a photoelectric encoder, a grating ruler measuring system and the like. The resolution of the magnetoelectric sensing system is difficult to achieve submicron level, and the problems of difficult integration of magnetic stripes, magnetic leakage and the like exist. The photoelectric encoder comprises a photoelectric encoder and a grating ruler which are used for measuring in a photoelectric sensing mode, and has the problems of high manufacturing cost, large volume, high requirement on actual environment and the like. The SNAP structure microcavity as a high-performance optical resonant cavity has great potential in the field of high-precision displacement sensing. Theoretically, the displacement sensor can reach submicron precision, is not easy to be interfered by external electromagnetic interference, is manufactured based on optical fibers, has low cost and small volume, and is suitable for high-precision displacement measurement in some microstructure fields. However, the microcavity axial size of a single SNAP structure is limited, and large-range displacement sensing is difficult to realize. Therefore, in order to solve the problem of limited axial measurement range of the SNAP structure microcavity and promote its application in the field of wide-range displacement sensing, a novel displacement sensing scheme and system need to be developed.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a displacement sensing system based on a double-chain SNAP structure microcavity array.

The purpose of the invention is realized by the following technical scheme:

a displacement sensing system based on a double-chain SNAP structure microcavity array mainly comprises a tunable laser, a polarization controller, a coupling waveguide, SNAP structure microcavity array double chains, a displacement device, a photoelectric detector and a computer. The tunable laser is connected with the polarization controller, the polarization controller is connected with the coupling waveguide, the coupling waveguide is connected with the photoelectric detector, the output end of the photoelectric detector is connected with the data input port of a computer, the surface nano axial photon structure microcavity array double chains are fixed on the displacement device, and the position device is arranged on the moving platform.

The tunable laser generates continuous laser with tunable wavelength and inputs the laser into an optical fiber, the polarization controller controls the polarization state of light waves in the optical fiber, the coupling waveguide couples the light waves in the optical fiber into SNAP structure micro-cavities with two chains through an evanescent field, the photoelectric detector is used for converting optical signals into electric signals, the double chains of the SNAP structure micro-cavity array are core devices of a sensing system and used for generating resonant light wave signals, and the displacement device is used for adjusting the displacement of the micro-cavity array relative to the coupling waveguide, so that the SNAP structure micro-cavity array moves relative to the coupling waveguide, and the coupling position of the micro-cavities and the waveguide is changed to change the Q value and the transmittance of a resonant mode in the micro-cavities. And the photoelectric detector is input into the computer for processing after measuring the resonance signal.

Further, the coupling waveguide may be a micro-nano tapered fiber, a coupling prism, an integrated optical waveguide, a ground tilt fiber, or a fiber grating.

Furthermore, each SNAP structure on the microcavity array is a microcavity, the SNAP structures on the two chains have the same axial length, and the longitudinal section shape of the SNAP structure can be a parabola shape, a Gaussian curve shape or a trapezoid shape.

Furthermore, the two SNAP microcavity array chains are placed in parallel, the distance is controlled to be more than 1mm, and the distance of half SNAP structure length is staggered in the axial direction.

Furthermore, ERV between the two SNAP microcavity array chains is different, so that resonance modes generated by different chains are convenient to distinguish on a resonance spectrum.

Further, the coupling waveguide is always kept in contact with the SNAP structure microcavity array during the working process.

Further, the SNAP structure microcavity array is obtained by utilizing arc discharge, carbon dioxide laser or ultraviolet light to act on optical fibers, the axial length L of a single microcavity of the SNAP structure is 0.5-1.5 mm, the number of the arrays can be determined according to actual needs without limitation, and the ERV of the surface nano axial photon structure microcavity is 10-100 nm.

The invention also discloses a method for realizing the displacement sensing system based on the surface nano axial photon structure microcavity array structure, which mainly comprises the following steps:

step S1: laser emitted from the tunable laser is acted by the polarization controller and then input into the tapered fiber waveguide, the laser is coupled into the SNAP structural microcavity through the evanescent field of the tapered fiber, corresponding resonance spectrum data are measured by the photoelectric detector, and the data input into the computer are processed to obtain a resonance spectrum.

Step S2: when the displacement device moves in a single direction, the SNAP structure microcavity array generates displacement relative to the coupling optical waveguide, accordingly, the Q value and the transmittance of each axial mode in a resonance spectrum will change, after the Q value or the transmittance is subjected to binary coding, the characteristics are identified through a computer, the position where coupling occurs can be mapped, and displacement measurement within half of the length of the SNAP structure can be realized based on the effect. Because ERV between the double-chain SNAP structure arrays is different, resonance modes of the double-chain SNAP structure arrays on a resonance spectrum can be distinguished, and on the basis, the resonance spectrum generated by SNAP micro-cavities in the double chains can be switched and used in sequence every time the length of the double-chain SNAP structure is spanned, so that full-range displacement sensing can be realized.

The working process and principle of the invention are as follows: according to the scheme, by utilizing the principle that mode field distribution and resonance spectrum characteristic parameters of the microcavity depend on cavity ERV, the SNAP structure microcavity arrays are manufactured on the optical fiber through a certain processing means, the two SNAP structure microcavity arrays are distributed in a staggered mode, the two SNAP structure microcavity arrays have half length difference of the SNAP structure, and the microcavity arrays are fixed through a displacement device and are mutually coupled with the coupling waveguide. The variation of the SNAP structure radial dimension is extremely small and is only in the nanometer level, so that the excitation of a high-order mode can be well inhibited. The change of a resonance mode is caused by changing the relative displacement of the coupling waveguide and the microcavity, the change of a corresponding Q value and the change of the light wave transmittance are represented on a mode spectrum, binary coding is carried out by utilizing the parameters, and the binary coding is mapped to a corresponding coupling position; when the parameters change, the corresponding binary codes change simultaneously, the indicated displacement also changes correspondingly, and high-resolution sensing is realized in each coding region according to the resonance mode with the highest sensitivity; and then high-resolution sensing of the displacement of half the length of the SNAP structure is realized. By arranging the SNAP structure microcavity array double chains with different ERVs, the microcavities on the two chains can be coupled with the coupling waveguide at the same time, and two resonance regions can appear on a resonance spectrum because the resonance center wavelengths of the resonance spectrum generated by the two chains are different. If the resonance data of the region with the smaller resonance wavelength is used for measuring the displacement in the length of a half SNAP structure, when the coupling waveguide is coupled with the position with the largest radius of the microcavity, the phenomenon that all even-order modes disappear appears on the resonance spectrum of the microcavity, the phenomenon is used as a switching signal, and then the resonance data of the region with the larger resonance wavelength is used for measuring the displacement of the length of the SNAP structure; the steps are repeated, and continuous measurement of the large-range displacement can be realized.

Compared with the prior art, the invention also has the following advantages:

(1) the displacement sensing system based on the double-chain SNAP structure microcavity array has submicron resolution, and is small in size, simple to manufacture, low in cost and suitable for microstructure measurement occasions.

(2) The double-chain SNAP structure microcavity array in the displacement sensing system based on the double-chain SNAP structure microcavity array provided by the invention always keeps contact with the coupling waveguide in the working process, and the weak electrostatic force between the double-chain SNAP structure microcavity array and the coupling waveguide provides stability for the system, so that the whole system has better anti-vibration interference capability.

(3) The displacement sensing system based on the double-chain SNAP structure microcavity array provided by the invention realizes large-range and high-precision displacement sensing, and overcomes the defect that the measurement of large-range displacement cannot be realized due to the fact that the axial length of a single SNAP structure microcavity is small.

Drawings

FIG. 1 is a schematic structural diagram of a displacement sensing system based on a double-chain SNAP structure microcavity array provided by the invention.

Fig. 2 is a schematic view of an installation structure of the double chains of the microcavity array of the SNAP structure and the displacement device provided by the invention.

FIG. 3 is a theoretical resonance mode spectrum of SNAP-structured microcavities with different ERVs provided by the present invention.

FIG. 4 is a graph showing the relationship between transmittance and displacement for each mode provided by the present invention.

The reference numerals in the above figures illustrate:

the method comprises the following steps of 1-tuning a laser, 2-polarization controllers, 3-coupling waveguides, 4-SNAP structure microcavity arrays, 5-displacement devices, 6-photodetectors and 7-computers.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer and clearer, the present invention is further described below with reference to the accompanying drawings and examples.