Sensing Characteristics of Fiber Fabry-Perot Sensors Based on Polymer Materials

Zheng-Da Liu,Yanjun Fu,Sheng-Peng Wan,Hau-Ping Chan,Jinhui Yuan,Juan Liu,Mengyu Wang,Qiang Wu,Xingdao He,Bin Liu

doi:10.1109/access.2020.3025330

Abstract

A simple optic-fiber Fabry-Perot (FP) sensing technique was proposed and experimentally investigated by using polymer material to connect the ends of two singlemode fibers. Four different polymer materials (benzocyclobutene (BCB), UV88 (Relentless, China), Loctite3525 (HenKel, Germany), and NOA68 (Norland, USA)) filling the FP cavity were used to comparatively study the sensing performance of temperature, strain and refractive index. The result shows that the FP sensor with BCB has excellent repeatability with good linear response to temperature in a wide range from room temperature to 250 °C, which is much larger than that of other three materials (<; 90 °C), while UV88 with a cost of less than 1/10 of the other three polymer materials has the best sensitivity to strain and temperature. In addition, the FP sensor was firstly applied to measure ultraviolet (UV) light intensity. The test results demonstrate that the proposed FP sensor structure has a good linear response and repeatability to UV intensity for all four polymer materials, and Loctite3525 has the highest sensitivity (0.0087 nm/(mw/cm 2 )) and the best repeatability among the four polymer materials.

Highlights

An optical fiber Fabry-Perot (FP) sensor is a type of interference sensor [1], which can be used for sensing of temperature [2]–[6], strain [7]–[10], refractive index (RI) [11]–[13], pressure [14]–[16], magnetic field [17], [18], sound pressure [19] and so on
For BCB which waterproof performance is excellent, we found that the reflection spectrum has no significant shift with increasing of surrounding RI [shown in Figs. 8(d) and (h)], the FP structure with BCB has residual sensitivity to RI, which can be used to avoid the problem of cross-sensitivity between temperature and refractive index in temperature sensing applications
A simple and low-cost optical fiber FP sensor structure was proposed by filling polymer materials (UV88, Locatite3525, NOA68 and BCB) between the ends of two singlemode fiber (SMF)

Summary

INTRODUCTION

An optical fiber Fabry-Perot (FP) sensor is a type of interference sensor [1], which can be used for sensing of temperature [2]–[6], strain [7]–[10], refractive index (RI) [11]–[13], pressure [14]–[16], magnetic field [17], [18], sound pressure [19] and so on. In the case of UV sensing, narrow band gap semiconductors Si and GaAs are widely used to sense UV intensity Their UV sensitivity is relatively low [30], and the semiconductor material is normally sensitive to infrared and visible light and cause cross-effects [31]–[33]. A new application for UV sensing with the FP sensor was proposed, and experimental results showed that it has a good sensitivity and linear response to UV intensity without cross-sensitivity to visible light

THEORETICAL ANALYSIS

CONCLUSION