Multi-point fiber refractometer using Fresnel reflection and a coherent optical frequency-domain multiplexing technique.

We demonstrate a simple multi-point refractometer based on the coherent optical frequency-domain multiplexing technique. As local refractive index sensors, interferometers of different lengths formed between cleaved fiber tips and reference weak reflectors are employed. Referent reflectors were fabricated by splicing into lead SMF-28 fiber a very short section of hollow optical fiber using a standard fiber splicer and a cleaver with an optical microscope.

Overlapped fiber-optic Michelson interferometers for simultaneous refractive index measurement at two sensing points.

We present a fiber refractometer based on the implementation of overlapped Michelson interferometers; the refractometer allows simultaneous refractive index measurement at two sensing points for samples discrimination. The fiber refractometer uses the Fresnel reflection in each fiber tip of the overlapped interferometers to generate the interference signal. Experimental results, implementing the two sensing points, for discrimination between non-contaminated and contaminated distilled water are presented.