Novel NCF-FBG Interferometer for Simultaneous Measurement of Refractive Index and Temperature

A simple and compact interferometer structure based on no-core fiber (NCF) and fiber Bragg grating (FBG) is proposed for simultaneous measurement of surrounding refractive index (SRI) and temperature. Two methods of measurement may be used here: 1) the sensing information can be analyzed by the wavelengths shift of the NCF-based interferometer and one arbitrarily FBG-reflected modes, or 2) they can be solely extracted through both wavelength and power of each FBG reflected mode. Moreover, experimental results indicate that the SRI sensitivity of the FBG reflected core mode is up to 160.23 dB/RIU at a range from 1.3330 to 1.3780, which is the highest value to our knowledge.