An all-silica fiber-optic Fabry-Perot etalon air pressure sensor

This paper presents an all-silica akinetic fiber-optic air pressure sensor based on a rigid fiber-coupled Fabry-Perot etalon (FPE) with a transparent central opening. The sensing principle relies on measuring pressure-induced refractive index changes of the gas within the FP cavity. The sensor comprises a lead-in fiber, in-fiber collimator, and an open micro-cavity formed by a square glass tube, all assembled via hydroxide-catalysis bonding (HCB) for polymer-free, room-temperature bonding and high-precision alignment. Experimental results demonstrate a high pressure sensitivity of 8.09 nm/kPa and resolution of 12.36 Pa. The all-silica design enables reliable operation from 20 ºC to 600 ºC, exhibiting low temperature sensitivity (0.36 nm/ºC) and minimal pressure error (0.04 kPa/ºC), attributed to matched thermal expansion coefficients and the inorganic HCB-formed silicate network. A 10-hour stability test shows no more than 1.5 nm cavity length fluctuation (0.19 kPa), confirming long-term reliability. This sensor’s high sensitivity, thermal stability, and robust performance highlight its potential for altitude and airspeed applications.