Miniature Fiber-Optic Temperature-Pressure Sensor Enabled by Dual Parallel Fabry-Pérot Cavities

As science and industry advance at a rapid pace, the requirement for synchronized monitoring of several parameters is increasing. In response, a miniature temperature-pressure sensor (110 μm in diameter and 100 μm in length) has been proposed and optimized. This sensor uses dual parallel fiber Fabry-Pérot (FP) cavities, formed inside a cup-shaped silicon pillar created using deep reactive ion etching (DRIE) technology. A multi-core optical fiber is attached to the silicon pillar to facilitate signal propagation. One FP interferometer is established within a fully enclosed air cavity, acting as a pressure sensor. The other FP cavity, located in the silicon cup wall, functions as a thermometer and compensator due to its temperature response properties. The sensor achieves a temperature sensitivity of 94.47 pm/°C within a temperature range of 40 °C and a pressure sensitivity of -4.33 pm/kPa in the hydraulic pressure range of 100 kPa to 1000 kPa. Additionally, the sensor provides a temperature resolution of 0.0058 °C and a pressure resolution of 1.36 kPa. The sensor’s mass production potential, thanks to DRIE technology, along with its high reliability and repeatability, makes it an excellent candidate for the development of microsensors.