Continuous-Wave Fiber Cavity Ringdown Pressure Sensing Based on Frequency-Shifted Interferometry.

Yiwen Ou,Chunfu Cheng,Li Qian,Zehao Chen,Zhangyong Yang,Hui Lv

doi:10.3390/s18041207

Abstract

We present a continuous-wave fiber cavity ringdown (FCRD) pressure-sensing method based on frequency-shifted interferometry (FSI). Compared with traditional CRD or FCRD techniques, this FSI-FCRD scheme deduces pressure by measuring the decay rate of continuous light exiting the fiber ringdown cavity (RDC) in the spatial domain (i.e., the CRD distance), without the requirement for optical pulsation and fast electronics. By using a section of fiber with the buffer layer stripped in the fiber RDC as the sensor head, pressures were measured within the range from 0 to 10.4 MPa. The sensitivity of 0.02356/(km∙MPa) was obtained with a measurement error of 0.1%, and the corresponding pressure resolution was 0.05 MPa. It was found that the measurement sensitivity can be improved by enlarging the interaction length of the sensor head. The results show the proposed sensor has the advantages of simple structure, low cost, high sensitivity, and high stability in pressure detection.

Highlights

The role of pressure sensors is becoming increasingly prominent in the fields of energy, chemical industry, aerospace, transportation, large civil engineering, etc
This is the first time frequency-shifted interferometry (FSI)-fiber cavity ringdown (FCRD) has been used to detect pressure, and the results show that the new type of pressure sensor explored in this work would be a superior alternative to pressure measurement in the aspects of low cost, simple structure, high sensitivity, and high stability
The two interference signals of the Sagnac interferometer were converted into electrical signals and subtracted by a balanced detector (BD) (New Focus) to eliminate the direct current (DC) noise, and the output of the BD was recorded by a DAQ (NI USB-6361)

Summary

Introduction

The role of pressure sensors is becoming increasingly prominent in the fields of energy, chemical industry, aerospace, transportation, large civil engineering, etc. Yang et al reported static ice pressure detection of hydraulic structures based on FCRD technique, and a high sensitivity of 0.0098/(s·KPa) was attained [21] Despite these successes, pulsed light is still needed in the fiber RDC for an observable CRD event in FCRD, as well as in CRD. 0.02356/(km·MPa) with a baseline stability of 0.1% and a resolution of 0.05 MPa, which is better than some results reported by traditional FCRD techniques This is the first time FSI-FCRD has been used to detect pressure, and the results show that the new type of pressure sensor explored in this work would be a superior alternative to pressure measurement in the aspects of low cost, simple structure, high sensitivity, and high stability

Operating Principle

Experiments and Results

Conclusions