High-sensitivity fiber refractive index sensor formed by sandwiching a thinned taper between two abrupt tapers

摘要

A fiber refractive index (RI) sensor based on a Mach-Zehnder interferometer (MZI) formed by sandwiching a thinned taper between two abrupt tapers. The abrupt tapers and the thinned taper are easily fabricated by a commercial fiber fusion splicer and a homemade tapering machine, respectively. The sensor has been experimentally demonstrated for RI sensing by monitoring its spectral shifts. The experimental results show that the sensor with a thinner taper has higher sensitivity due to the strong evanescent field interaction. A sensitivity of 3808.4 nm/RIU (refractive index unit) is obtained, which is about 100 times higher than that of the conventional taper-based MZI sensors.