LAUSR

The birefringence properties of two types of side‐hole fibers have been numerically studied, based on which a Sagnac fiber interferometer employing ethanol‐filled side‐hole fibers is proposed and experimentally demonstrated for high‐sensitive temperature measurement. Thanks to highly temperature‐sensitive refractive index of ethanol infiltrated in the air holes of side‐hole fibers, high‐sensitive temperature measurement could be realized by monitoring fiber‐birefringence‐induced resonance wavelength shift of the fiber Sagnac interferometer in response to environmental temperature variation. Experimental results show that within a temperature range of 26°C to 54°C, there exists some critical temperature point around 40°C, on both sides of which the resonance dips exhibit inverse temperature‐dependent shift behaviors. A temperature sensitivity of 1.10 nm/°C is experimentally achieved for our proposed side‐hole fiber Sagnac interferometer.