Simple Fresnel Reflection-Based Optical Fiber Sensor for Multipoint Refractive Index Measurement Using an AWG

A simple Fresnel reflection-based optical fiber refractometer for simultaneous multipoint measurement based on an arrayed-waveguide grating (AWG) is proposed. The AWG is used as a demultiplexing unit and different channel fibers of the AWG work as different sensor heads. Every channel light divided by the AWG is marked with a different central wavelength, and its reflection from its fiber-solution interface is used to measure the RI of the inserted solution. By using the AWG unit, a simple and compact structure sensor for multipoint sensing is achieved. Experiment results show that the sensor works well and the average sensitivity is ~ 01.9 dB/RIU for refractive indices, in the range of 1.33-1.42.