Large dynamic range pressure sensor based on two semicircle-holes microstructured fiber

Zhengyong Liu,Lin Htein,Hwa-Yaw Tam,Kin-Tak Lau,Kang-Kuen Lee

doi:10.1038/s41598-017-18245-6

Abstract

This paper presents a sensitive and large dynamic range pressure sensor based on a novel birefringence microstructured optical fiber (MOF) deployed in a Sagnac interferometer configuration. The MOF has two large semicircle holes in the cladding and a rectangular strut with germanium-doped core in the center. The fiber structure permits surrounding pressure to induce large effective index difference between the two polarized modes. The calculated and measured group birefringence of the fiber are 1.49 × 10−4, 1.23 × 10−4, respectively, at the wavelength of 1550 nm. Experimental results shown that the pressure sensitivity of the sensor varied from 45,000 pm/MPa to 50,000 pm/MPa, and minimum detectable pressure of 80 Pa and dynamic range of better than 116 dB could be achieved with the novel fiber sensor. The proposed sensor could be used in harsh environment and is an ideal candidate for downhole applications where high pressure measurement at elevated temperature up to 250 °C is needed.

Highlights

Microstructured optical fibers (MOFs) possess many advantages in sensing applications because of the flexibility in modifying their mechanical and optical properties, tailored for different applications
Pressure sensor constructed with the novel MOF in a Sagnac interferometer configuration exhibited pressure sensitivity up to 50,000 pm/MPa, which is more than 10 times higher than any reported pressure sensors based in SI configuration
In contrast to other types of side hole fiber where the long axis of elliptical core is parallel to the fiber symmetry axis[25], the long axis of the elliptical core of the two semicircle holes MOF (TSH-MOF) is perpendicular to the fiber symmetry axis

Summary

Introduction

Microstructured optical fibers (MOFs) possess many advantages in sensing applications because of the flexibility in modifying their mechanical and optical properties, tailored for different applications. Even This type of miniature pressure sensors is commercially available from FISO Technologies Inc. and are designed for medical applications owing to the high sensitivity in small pressure range. Such extrinsic sensors cannot sustain high pressure as diaphragm could be damaged and the performance highly depends on the sensor fabrication process and diaphragm materials. Optical fiber sensors based on fused silica have been demonstrated to withstand very high pressure and measured pressure up to 200 MPa was reported[12,24]. Such optical fiber sensor would need to be able to measure pressure as small as

Methods

Results

Conclusion