Fabrication And Sensing Characteristics Of Spatially Structure Modulated M-Z Fiber Optic Sensor

The purpose of this paper is to prepare M-Z fiber optic sensors through different spatial structures,and to realize the research of sensing characteristics according to the characteristics of spatial structures.The spatially structure modulated M-Z fiber optic sensor is used to characterize the characteristic parameters that the light wave changes indirectly or directly due to the external environmental factors.Therefore,it can be used as a sensor to detect external physical parameters.Firstly,in this chapter,the paper introduces the preparation of different spatial structure modulation M-Z fiber optic sensors based on spiral pre-twisted taper structure and analyzes their sensing characteristics.This paper mainly describes the spiral pre-twisted taper cascade optical fiber ball M-Z optical fiber sensor,in which the circular symmetry of the optical fiber ball is beneficial to detect the torsion characteristics of the spiral pre-twisted taper.The experimental results show that the peak of the M-Z fiber sensor is sensitive to torsion,and the torsional sensitivity in the counterclockwise and clockwise directions is 0.083 nm/(rad/m)and-0.378 nm/(rad/m),respectively.At the same time,the torsional direction can be distinguished according to the red-shift or blue-shift of the wavelength in different directions.The absolute value of torsion sensitivity can also be used to determine the direction of torsion.In addition,based on the MMFS interferometer as the carrier,the embedded spiral pre-twisted taper cascade MMFS fiber sensor is constructed.Experimental data show that the sensor is sensitive to torsional peaks,and the torsional sensitivity in the counterclockwise and clockwise directions is 0.765 nm/(rad/m)and-0.902 nm/(rad/m),respectively.Therefore,this sensor can not only realize torsion measurement and torsion direction determination,but also has a multiple improvement in torsion sensitivity compared with the spiral pre-twisted taper cascade optical fiber ball M-Z optical fiber sensor.Secondly,by superimposing the spot of high-frequency CO₂laser,the etching modulation of optical fiber structure is realized.Based on the modulation,orthogonal sheets M-Z optical fiber sensor has been completed,the strain and temperature measurement,The results showed that the strain sensitivity of the interference peaks of 1324 nm and 1350 nm were-3.05 pm/??and-8.02 pm/??,respectively,and the corresponding temperature sensitivity were 61.4 pm/?and 58.6 pm/?,and the standard deviation of strain sensitivity under different temperature was 0.097 pm/??and 0.630 pm/??,respectively.Finally,based on the same method,the milling plane M-Z fiber optic sensor was fabricated,but the results showed no obvious interference fringes.On this basis,the milling plane LPFG was prepared.The bending sensitivity of the resonant peak of 1498 nm in the directions of Y+,X+and Y-(respectively the directions specified in the X and Y axes in the paper)was-10.02 nm/m^-1,-2.42 nm/m^-1and 8.64 nm/m^-1,respectively.The shaped core milling plane M-Z fiber optic sensor was processed by melting method,and the results showed that the milling plane M-Z fiber optic sensor had obvious interference.The experimental data showed that the bending sensitivity of interference peak 1548 nm in Y+,X+and Y-direction was-12.12 nm/m^-1,-2.57 nm/m^-1and 7.27 nm/m^-1,respectively.The bending sensitivity of 1613 nm in Y+,X+and Y-direction was-10.91 nm/m^-1,8.86 nm/m^-1and 7.88 nm/m^-1,respectively.Two kinds of optical fiber sensors based on milling plane space structure are verified,which can realize the study of bending characteristics in different directions of optical fiber.In this paper,the spiral pre-twisted taper M-Z fiber sensor,embedded spiral pre-twisted taper MMFS fiber sensor,orthogonal slice M-Z fiber sensor and shaped core milling plane M-Z fiber sensor were prepared by using different spatial structures,and the sensing characteristics were studied respectively.