Investigation by simulation of the highest sensitivity interferometric pressure sensor at the end of a micro-structured optical fiber

Abstract

One of the most prevalent techniques used in the construction of optical fiber-based pressure sensors is Fabry–Perot interferometry. This work presents a variety of interferometric sensors based on this feature. To achieve this, we used chemical etching (HF) to create conical cavities at the ends of the optical fibers single mode fiber (SMF) and graded index (GRIN) fiber, where the first gold (Au) deposition allows us to create half-mirrors. So the interface (core/Au) represents the first reflective surface. After filling each micro-cavity with a quantity of polydimethylsiloxane (PDMS) type polymer to form a flexible micro-lens, and proceeding to a second deposition of gold (Au), we got the second reflective surface (PDMS/Au). The sensor with the highest sensitivity to pressure and temperature, namely 0.065 nm/KPa and 0.24 nm/°C, was obtained for a micro-cavity length of 35 μm, a diameter of 60 μm, and a micro-lens thickness of 20 μm, respectively. Analysis and simulation were performed using COMSOL Multiphysics to develop the sensor.