Fiber-optic Fabry-Perot pressure sensor based on sapphire direct bonding for high-temperature applications.

Abstract

In this study, a fiber-optic Fabry-Perot (FP) high-temperature pressure sensor based on sapphire direct bonding is proposed and experimentally demonstrated. The sensor is fabricated by direct bonding of two-layer sapphire wafers, including a pressure diaphragm wafer and a cavity-etched wafer. The sensor is composed of a sensor head that contains a vacuum-sealed cavity arranged as an FP cavity and a multimode optical fiber. The external pressure can be measured by detecting the change in FP cavity length in the sensor. Experimental results demonstrate the sensing capabilities for pressures from 20kPa to 700kPa up to 800°C.