Alcohol-filled side-hole fiber Sagnac interferometer for temperature measurement

A temperature sensor with an alcohol-filled side-hole fiber (SHF) based Sagnac interferometer is first proposed and experimentally demonstrated. Due to the temperature-dependent refractive index of the alcohol liquid filled in the air holes of the SHF, interference pattern of the Sagnac interferometer shifts with temperature variation. Sensitivity of 86.8 pm/°C is achieved, which is about eight times higher than that of a fiber Bragg grating sensor.