Range Tunable Optical Fiber Micro-Fabry–Pérot Interferometer for Pressure Sensing

We propose and demonstrate a pressure sensor based on an air cavity formed by the end face of single-mode fiber and a barium titanate microsphere surface. The distance between the fiber end and the microsphere surface can be easily adjusted to allow tuning of the measurement range. In the experiment, the measurement range achieved is from 0-0.1 to 0-1 MPa, and the pressure sensitivities obtained are between 3.23 and 4.10 nm/MPa. The sensor exhibits a low-temperature cross-sensitivity of less than ~1 kPa/°C and has the potential to be used in a gas refractive index measurement.