Twin-core fiber-based sensor for measuring the strain and bending simultaneously

Abstract

A novel composite interferometer sensor is presented and its sensing characteristics are investigated. Based on the infiber integrated Michelson interferometer, a quartz tube is used to encapsulate the ends of the twin-core fiber and single mode fiber to form the dual extrinsic FP cavities. Thereby, the Michelson and FP configurations are integrated into a single fiber, which we call it Michelson-FP composite interferometer sensor. The novel sensor can respond to the axial strain and radial bending simultaneously. We have derived and analyzed the interferometer principle of the new structure. The analysis results show that the interferometer sensor could be considered as the superposition of Michelson interferometer and FP interferometer. Moreover, we establish a testing system and conduct a series of experiments to investigate the strain and bending characteristics. We measure the reflection spectra with the spectrum analyzer. The spectral response of the composite interferometer sensor presents two pattern fringes with different frequencies due to the respective optical path interferometers. The experimental results indicate that the composite interferometer sensor is very sensitive to the strain and bending characteristics, and the presented sensor has different strain and bending sensitivity coefficients. Due to these characteristics, the presented sensor might be able to measure the strain and bending characteristics simultaneously. In conclusion, the presented novel interferometer sensor is of compact structure, high integration and good strain and bending sensing characteristics. Thus, many types of fiber-optic sensors may be built based on it.Keywords: twin-core fiber, Michelson interferometer, Fabry-Perot interferometer, Michelson-FP composite interferometer sensor, simultaneous measurement of strain and bending characteristics.

High temperature probe sensor with high sensitivity based on Michelson interferometer

“…In 2012, Byeong Ha Lee et al demonstrate a PCF-based Michelson interferometer and the experiment result shows that the sensor's temperature is insensitive [18]. In 2013, Yuanyuan Yang et al make an in-fiber integrated Michelson-FP composite interferometer, a quartz tube is used to encapsulate the ends of the twin-core fiber and single mode fiber to form the dual extrinsic F-P cavities [19]. In the same year, Kun Yang et al demonstrate a piece of multimode optical fiber and weld end with silver plated film SMF for temperature measurement from 470 to 600°C with a sensitivity of 0.120 pm/°C [20].…”

“…At present, a variety of optical fiber sensors [1,2], such as Fiber Bragg grating (FBG) [3,4], long-period fiber grating (LPG) [5,6], Mach-Zehnder interferometer(MZI) [7][8][9][10][11][12][13], Fabry-Perot interferometer (F-P) [14][15][16][17] have been studied extensively. In particular, with the method of Michelson interferometer [18][19][20] to measure temperature becomes a new trend. In 2012, Byeong Ha Lee et al demonstrate a PCF-based Michelson interferometer and the experiment result shows that the sensor's temperature is insensitive [18].…”