Simultaneous measurement of temperature and pressure with cascaded extrinsic Fabry–Perot interferometer and intrinsic Fabry–Perot interferometer sensors

Yinan Zhang,Lei Yuan,Hai Xiao,Xinwei Lan,Jie Huang

doi:10.1117/1.oe.53.6.067101

Abstract

This paper presents an approach for simultaneous measurement of temperature and pressure using miniaturized fiber inline sensors. The approach utilizes the cascaded optical fiber inline intrinsic Fabry–Perot interferometer and extrinsic Fabry–Perot interferometer as temperature and pressure sensing elements, respectively. A CO2 laser was used to create a loss between them to balance their reflection power levels. The multiplexed signals were demodulated using a Fast Fourier transform-based wavelength tracking method. Experimental results showed that the sensing system could measure temperature and pressure unambiguously in a pressure range of 0 to 6.895×105 Pa and a temperature range from 20°C to 700°C.

Highlights

Pressure and temperature are two important parameters in the well and reservoir down-hole monitoring
We reported a miniature, all-fiber intrinsic Fabry–Perot interferometer (IFPI) and extrinsic Fabry–Perot interferometer (EFPI) hybrid sensor suitable for simultaneous measurement of temperature and pressure
The IFPI was primarily sensitive to temperature but insensitive to pressure variations

Summary

Introduction

Pressure and temperature are two important parameters in the well and reservoir down-hole monitoring. Continuous, and real-time data of pressure and temperature helps in oil and reservoir management.[1] Sensors with dual-parameter sensing capability and survivability in the down-hole harsh environment are highly necessary in such applications. Fiber-optic sensors, with advantages such as small size, low loss, high sensitivity, resistance to harsh environments, and multiplexing capability, are good candidates for pressure and temperature down-hole monitoring. This article presents a new method for dual-parameter sensing using the cascaded intrinsic Fabry–Perot interferometer (IFPI) and extrinsic Fabry–Perot interferometer (EFPI) sensors. These sensors are fabricated using a femtosecond (fs) laser. The EFPI is positioned at the fiber tip and consists of an fs laser thinned silica diaphragm and a sealed air cavity

Sensor Fabrication

Sensor Principle

Signal Processing

Experimental Results

Conclusion