Optical Fiber Refractometer Based on a Long-Period Grating Inscribed in a Fiber Loop Mirror

An optical fiber refractometer based on a long-period grating (LPG) and a polarization maintaining fiber (PMF) in a fiber loop mirror (FLM) was presented. It is found that the transmitted optical intensity from the loop mirror will be changed with the variation of the ambient refractive index (RI). Experiment results show that maximum sensitivity of 103.2dB/RIU has been achieved within the RI range of 1.38-1.45.