阅读说明：本技术 一种双波导耦合snap结构微腔阵列的位移传感系统 (Displacement sensing system of double-waveguide coupling SNAP structure microcavity array ) 是由 董永超 陈剑 孙鹏辉 赵泽政 王晗 于 2020-06-10 设计创作，主要内容包括：本发明公开了一种双波导耦合SNAP结构微腔阵列的位移传感系统,包括可调谐激光器、偏振控制器、双耦合波导、SNAP结构微腔阵列、位移装置、光电探测器及计算机。可调谐激光器产生的扫频激光,经过偏振控制器和耦合波导进入SNAP结构微腔阵列,经光电探测器对输入光波信号进行探测后,输出给计算机,经处理后测得位移量。当SNAP结构微腔阵列相对于两个耦合波导移动时,谐振谱中各谐振模式的特征参数将发生规律性变化。通过使用其中一个耦合波导的光波信号可实现半个SNAP结构长度的位移量的精密测量。通过切换使用两根耦合波导的信号可达到全范围位移的测量。因此,本发明具有大量程、高分辨率、体积小、制作简单、成本低等优点。(The invention discloses a displacement sensing system of a double-waveguide coupling SNAP structure microcavity array, which comprises a tunable laser, a polarization controller, a double-coupling waveguide, an SNAP structure microcavity array, a displacement device, a photoelectric detector and a computer. Sweep-frequency laser generated by a tunable laser enters the SNAP structure microcavity array through the polarization controller and the coupling waveguide, an input optical wave signal is detected by the photoelectric detector and then output to a computer, and displacement is measured after processing. When the SNAP structure microcavity array moves relative to the two coupling waveguides, the characteristic parameters of each resonance mode in the resonance spectrum change regularly. By using the light wave signal of one of the coupling waveguides, precise measurement of the displacement of half the length of the SNAP structure can be achieved. Full range displacement measurement can be achieved by switching the signals using two coupled waveguides. Therefore, the invention has the advantages of wide range, high resolution, small volume, simple manufacture, low cost and the like.)

1. A displacement sensing system of a double-waveguide coupling SNAP structure microcavity array is characterized by comprising a tunable laser, a polarization controller, a double-coupling waveguide, an SNAP structure microcavity array, 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 double-coupling waveguide; the input end of the photoelectric detector is connected with the other end of the double-coupling waveguide, and the output end of the photoelectric detector is connected with the input end of the computer; the double-coupling waveguide is provided with two emergent ends and two incident ends, the emergent ends correspond to the incident ends one by one, and the emergent ends and the incident ends are arranged at intervals; the SNAP structure microcavity array is arranged between two emergent ends and an incident end of the double-coupling waveguide, so that laser is emitted from the emergent end and enters the incident end after passing through the SNAP structure microcavity array; the SNAP structure micro-cavity array is arranged on the displacement device; the displacement device is arranged on the mobile platform;

the tunable laser generates two paths of laser with tunable wavelength and inputs the two paths of laser into the polarization controller, and the two paths of laser are transmitted into the double-coupling waveguide by adjusting the polarization state of the optical wave; the exit end of the double-coupling waveguide is respectively coupled with two different areas of the SNAP structure microcavity array to form two coupling units, and laser meeting resonance conditions is coupled into the two different areas of the SNAP structure microcavity array through an evanescent field;

the photoelectric detector is used for converting the received optical signals into electric signals so as to obtain resonance spectrums of the two coupling units; the displacement device is used for adjusting the relative position of the SNAP structure microcavity array relative to the two coupling waveguides, so that the SNAP structure microcavity array moves relative to the double coupling waveguides, the coupling positions of the SNAP structure microcavity array and the double coupling waveguides are changed, and the Q value and the transmittance of the resonant mode in the SNAP structure microcavity are changed.

2. The displacement sensing system of the microcavity array of a dual-waveguide-coupled SNAP structure according to claim 1, wherein the dual-coupling waveguide is configured as a micro-nano tapered fiber, a coupling prism, a planar waveguide, a ground tilt fiber, or a fiber grating.

3. The dual-waveguide-coupled SNAP-structure microcavity array displacement sensing system according to claim 1, wherein each SNAP structure on the SNAP-structure microcavity array is a whispering gallery microcavity, and each SNAP structure has the same axial length and effective radius variation.

4. The displacement sensing system of the microcavity array of a dual-waveguide-coupled SNAP structure as claimed in claim 3, wherein the SNAP structure has a longitudinal cross-sectional shape that is parabolic, gaussian or trapezoidal.

5. The displacement sensing system of the microcavity array of a dual waveguide-coupled SNAP structure of claim 1, wherein the dual-coupled waveguides are disposed in parallel with a spacing therebetween of (N +1/2) times an axial length of the single SNAP structure, where N is a positive integer.

6. The dual-waveguide-coupled SNAP-structure microcavity array displacement sensing system of claim 1, wherein the dual-coupled waveguide is in constant contact with the SNAP-structure microcavity array during operation.

7. The dual-waveguide coupling SNAP structure microcavity array displacement sensing system of claim 1, wherein the SNAP structure microcavity array is obtained by arc discharge, carbon dioxide laser or ultraviolet light acting on a uniform optical fiber.

8. The dual-waveguide coupling SNAP structure microcavity array displacement sensing system according to claim 7, wherein the axial length of a single SNAP structure in the SNAP structure microcavity array is 0.5-1.5 mm, and the effective radius variation is 10-100 nm.

Technical Field

The invention relates to the technical field of optical sensing, in particular to a displacement sensing system of a double-waveguide coupling SNAP (surface nanometer Axial photon) structure microcavity array.

Background

The existing mature and widely applied displacement sensing measurement system comprises a grating ruler, a magnetic grating ruler, a laser ranging system, various measurement heads and the like based on a specific physical quantity sensing effect, and the displacement sensing measurement system has respective limitations while meeting various measurement requirements of an industrial field. Therefore, in order to meet the requirements of some specific applications, developing a novel displacement sensing technology has been a focus.

The whispering gallery mode microcavity is an optical device widely studied in the last two decades, and the extremely high Q value of the whispering gallery mode microcavity enables the whispering gallery mode microcavity to have extremely high sensitivity in the sensing field. The displacement sensing device based on the microcavity can realize submicron resolution, has the advantages of small volume and easy integration, and provides a good choice for measurement of a micro structure. A common implementation manner of microcavity displacement sensing is to detect the shift of the center wavelength of the resonant mode in the resonant spectrum, but since the center wavelength is easily affected by the stability of the instrument, environmental factors, and the like, it is difficult to implement stable sensing measurement in an actual environment. The SNAP structure microcavity has a regular resonance spectrum, the sensing of high-resolution displacement can be realized by comprehensively utilizing the Q values or transmittance of a plurality of resonance modes, and the high-resolution displacement sensing device has high stability. However, the axial length range of a single SNAP structure microcavity is limited, and is generally only several hundred micrometers, and single waveguide coupling can only ensure displacement measurement of half SNAP structure length, so that large-range displacement sensing cannot be realized. Therefore, in order to improve the displacement sensing performance of the microcavity based on the SNAP structure and realize high-resolution and wide-range sensing measurement, a novel displacement sensing method 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 of a double-waveguide coupling SNAP structure microcavity array.

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

a displacement sensing system of a double-waveguide coupling SNAP structure micro-cavity array is characterized in that based on Q values or transmittance change rules of a plurality of resonance modes, a single-waveguide coupling SNAP structure micro-cavity is utilized, and the displacement sensing characteristic of half of the length of the SNAP structure can be realized. The system realizes displacement sensing by using the double-coupling waveguide and the SNAP structure microcavity array, couples the spatial position of the double-coupling waveguide with different microcavities in the SNAP structure microcavity array through reasonable arrangement, and realizes displacement sensing in the range of the SNAP structure microcavity array by alternately using transmission spectrums obtained by the two coupling waveguides. The method can realize displacement sensing measurement in a large range while ensuring high resolution, and has the advantages of small volume and low manufacturing cost.

Specifically, the displacement sensing system provided by the invention mainly comprises a tunable laser, a polarization controller, a double-coupling waveguide, a SNAP structure microcavity array, 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 double-coupling waveguide, the double-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 SNAP structure microcavity array is fixed on the displacement device, and the position device is arranged on the movable platform.

The tunable laser generates two paths of laser with tunable wavelength and inputs the two paths of laser into the optical fiber; the polarization controller adjusts the polarization state of the light wave and sends the light wave into the double-coupling waveguide; the double-coupling waveguide is respectively coupled with the SNAP structure micro-cavities in two different areas to form two coupling units, and light waves meeting resonance conditions are coupled into the two SNAP structure micro-cavities through evanescent fields; the photoelectric detector is used for converting the received optical signals into electric signals so as to obtain resonance spectrums of the two coupling units; the SNAP structure microcavity array is a core device of a sensing system and determines the characteristics of resonant light wave signals; the displacement device is used for adjusting the relative position of the microcavity array relative to the two coupling waveguides, so that the SNAP structure microcavity array moves relative to the double coupling waveguides, and the coupling positions of the SNAP structure microcavity and the double coupling waveguides are changed, so that the Q value and the transmittance of the resonant mode in the SNAP structure microcavity are changed.

Further, the double-coupling waveguide can be a micro-nano tapered fiber, a coupling prism, a planar waveguide, a ground tilt angle fiber or a fiber grating.

Furthermore, each SNAP structure on the SNAP structure microcavity array is a whispering gallery microcavity, each SNAP structure has the same axial length and effective radius variation, and the longitudinal section shape of the SNAP structure can be a parabola shape, a Gaussian curve shape or a trapezoid shape.

Further, the double-coupled waveguides are arranged in parallel and are spaced by (N +1/2) times the axial length of the single SNAP structure, wherein N is a positive integer.

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

Further, the SNAP structure microcavity array is obtained by utilizing arc discharge, carbon dioxide laser or ultraviolet light to act on a uniform optical fiber, the axial length of a single SNAP structure in the SNAP structure microcavity array is 0.5-1.5 mm, the effective radius variation is 10-100 nm, and the array number can be determined according to actual needs without limitation.

The invention also discloses a method for realizing the displacement sensing system based on the double-waveguide coupling SNAP structure microcavity array, which mainly comprises the following steps:

step S1: laser emitted from the tunable laser is input into the double-coupling waveguide after being acted by the polarization controller, and light waves in the coupling waveguide are converted into electric signals through the photoelectric detector after passing through the SNAP structure microcavity and are sent to the computer for processing.

Step S2: when the displacement device moves along a certain direction, the SNAP structure microcavity array generates displacement change relative to the double-coupling waveguide. Correspondingly, the Q value or transmittance of each axial mode in the two coupling units corresponding to the resonance spectrums will change, and after each half distance of the SNAP structure axial length, the two resonance spectrums will periodically reappear each other. By comprehensively utilizing a plurality of axial modes of a single resonance spectrum, displacement sensing within half the length of the SNAP structure can be realized.

Step S3: even-order mode disappearance in the resonance spectrum is used as a switching signal, and the resonance spectrum data of the two coupling waveguides are alternately used to realize the measurement of the full-range displacement of the SNAP structure microcavity array.

The working process and principle of the invention are as follows: because the coupling strength of the resonance mode is determined by the overlapping integral of the mode field of the microcavity and the mode field of the coupling waveguide, for the coupling unit consisting of the single SNAP structure microcavity and the single waveguide, the influence rule of the coupling position on the resonance spectrum is determined by the field distribution rule of each axial mode of the SNAP structure microcavity. When the coupling position is changed due to displacement, the Q value or transmittance of each axial mode in the corresponding resonance spectrum is changed, and the high-precision displacement sensing can be realized by comprehensively utilizing the change rule of the Q value or the transmittance of the multi-order axial mode. However, since the SNAP structure is symmetrical about a central point in the axial direction, a single coupling unit can only realize displacement sensing of half the length of the SNAP structure. Two coupling units can be formed by preparing a SNAP structure microcavity array on an optical fiber and coupling the SNAP structure microcavity array with a double-coupling waveguide. When the SNAP structure microcavity array moves, the two resonance spectrums are regularly changed, and through signal switching, the resonance spectrum signals generated by the two coupling units are alternately used, so that the full-range displacement sensing of the SNAP structure microcavity array can be realized.

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

(1) the displacement sensing system of the double-waveguide coupling SNAP structure microcavity array can realize high-resolution and wide-range displacement measurement, and solves the defect that the single SNAP structure microcavity cannot realize wide-range measurement due to small axial length.

(2) The displacement sensing system of the double-waveguide coupling SNAP structure microcavity array has the advantages that the core component SNAP structure microcavity array is small in size, simple to manufacture and low in cost, and is suitable for microstructure measurement occasions.

(3) The displacement sensing system of the double-waveguide coupling SNAP structure microcavity array can homogenize errors and has strong anti-noise signal interference capability.

Drawings

FIG. 1 is a schematic structural diagram of a displacement sensing system of a dual-waveguide coupling SNAP structure microcavity array provided by the invention.

Fig. 2 is a schematic view of the assembly of the microcavity array of SNAP structure and the double-coupled waveguide provided by the present invention.

Fig. 3(a) and 3(b) are resonance spectrums of the corresponding outputs of the double-coupled waveguide when the microcavity array of the SNAP structure provided by the invention is located at six different positions.

Fig. 4(a) and 4(b) are graphs showing the transmittance of the first 8-order axial mode in the output spectrum of the double-coupled waveguide according to the change of the axial displacement of the microcavity array of the SNAP structure.

The reference numerals in the above figures illustrate:

the device comprises a tunable laser 1, a polarization controller 2, a double-coupling waveguide 3, a microcavity array with a 4-SNAP structure, a displacement device 5, a photoelectric detector 6 and a computer 7.

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.