Temperature Insensitive Strain Sensor with Asymmetrical Cascading Structure Based on Photonic Crystal Fiber in Chemical Corrosion

Guangwei Fu,Yunpu Li,Jiandong Yang,Weihong Bi,Xinghu Fu,Qifeng Li

doi:10.1155/2017/1489070

Abstract

In this paper, a corroded photonic crystal fiber (PCF) sensor is presented on the basis of core-offset splicing and waist-enlarged fiber taper corroded by hydrofluoric acid (HF). The Mach-Zehnder interference theory is used to analyze the relationship between transmission spectrum and strain. The final results obtained from experiments show that the strain sensor’s sensitivity is about −6.57 pm/με and the linearity is 0.99962 within the range of 0~1000 με, while the sensor is corroded by HF for 35 minutes at room temperature. In the temperature range of 20°C~80°C, the sensor’s sensitivity to temperature is only 1.63 pm/°C, which is insensitive to temperature. Because of its advantage compared to traditional optical fiber sensors, this sensor can avert the cross-sensitive problem when temperature and strain are measured together and has some other advantages including easily fabricated, simple structure and accurate sensitivity. It can be used in many fields, such as industrial production, monitoring, and aerospace.

Highlights

With the development of science and technology, the requirements for the safety monitoring of large-scale buildings and the sensitivity of high precision instruments are getting higher and higher
Corrosion-type photonic crystal fiber (PCF) sensor is prepared by core-offset splicing SMF and PCF firstly and excessive splicing PCF and SMF on fusion splicer
A sensor with PCF fusion length of 20 mm, offset of 7 μm, and taper diameter of 160 mm is corroded in hydrofluoric acid (HF) for 35 min and is washed by distilled water to clean the residual HF on sensor

Summary

Introduction

With the development of science and technology, the requirements for the safety monitoring of large-scale buildings and the sensitivity of high precision instruments are getting higher and higher. Osuch et al [8] ever reported a sensor using linearly chirped tapered fiber Bragg gratings to measure the strain. Noh et al [4] applied photonic crystal fiber to a Sagnac birefringence loop and got a sensitivity of 1.91 pm/με. All the sensors mentioned above have the problems that the sensitivity is not very high and the simultaneous measurement of the two parameters is cross-sensitive. In order to improve strain sensitivity of the sensor, a corrosion-type strain sensor of core-offset splicing and waist-enlarged photonic crystal fiber [10] (co&we-PCF) is presented. The sensor is prepared by corroding a section of the optical fiber between the two joints, core-offset joint, and excessive fusion joint, stretched in HF solution.

Theory Analysis

Experimental Results

Conclusion