Microgroove Based Optical Fiber Refractive Index Sensor

In this paper, an all-fiber novel fabricated Mach-Zehnder interferometer (MZI) based on refractive index (RI) sensor is presented and simulated. This RI sensor is composed of a single-mode fiber (SMF) with a core diameter of 9 mu m and a multimode fiber (MMF) with a core diameter of 105 mu m. The microgroove can be etched by femtosecond laser or ground by grinding machine technology. It greatly reduces the limitations of structure fabrication. The RI response of this sensor is obtained by beam propagation method. In the range of 1.33-1.334 RIU, the RI sensitivity is -10373 nm/RIU and the linearity is 99.98% by wavelength demodulation. The intensity demodulation shows a nonlinear trend, and the sensitivity increases with the increase of RI. The maximum RI sensitivity is -9614 dB/RIU, and the fitting is 98.69%. The structure has the advantages of simple manufacture, high sensitivity and good linearity. It is very suitable for the practical applications of RI sensing with high sensitivity.