Adiabatic fiber microtaper with incorporated an air-gap microcavity fiber Fabry-Pérot interferometer

This study demonstrates an adiabatic fiber microtaper with incorporated an air-gap microcavity fiber-Fabry-Pérot-interferometer to perform superior sensing characteristics. Optical interference fringes with good fringes contrast within bandwidth of 1250–1650 nm are performed experimentally. A highly spectral sensitivity of peak power with +3.65 dB/ °C (+9759 dB/RIU) is achieved when the device is operated under a fundamental-mode-cutoff (FMC) condition. By measuring peak power of the fringe, one can determine the temperature (T) or refractive index of environment. The proposed hybrid sensor is further applied to measure high T (∼1000 °C) of surrounding in non-FMC condition that obtains a good linearity of spectral response.