Microfiber Sagnac Interferometer for Sensing Applications

In this paper we propose an optical fiber-based refractive index and temperature sensor using an MNF (micro/nano fiber) inserted in a Sagnac loop interferometer [1]. A portion of the PMF is tapered into a micro/nano dimension to increase the interactions between a guided signal and the surrounding environment. Experimental tests have demonstrated low response to temperature and high sensitivity to refractive index change of a liquid surrounding the MNF. It has been shown that the sensitivity of the setup under test to temperature decreases when a longer MNF is used. The maximum sensitivity for a refractive index achieved equals to 1068nm/RIU, which was obtained by a 4.7-mm long MNF with a diameter of 30 mu m.