Design and development of a high sensitive low cost fiber optic refractometer

Abstract

A simple and low-cost fiber optic refractometer has been designed and demonstrated. The sensor is configured by etching a short region of a standard single-mode circularly bent fiber. Circularly bent three fiber loops are etched in equal lengths and arranged parallel to each other. The working principle of the sensor is by detecting the evanescent field modulation with respect to the change in ambient refractive index. In the present study glycerin solution with various concentrations, possessing different refractive indices is chosen as the ambient. Bent and etched optical fiber sensors have increased sensing capabilities but they are very much prone to fracture and breakage. The proposed sensor is stable showing very less tendency towards any breakage or fracture. The sensitivity of the sensor is tested for glycerin with different concentrations. It is evident from the experimental results that with the increase of glycerin concentration the output intensity of the sensor is decreased linearly. The proposed sensor may find applications in detecting various chemical species and biochemical applications. Keywords: Refractometer, Evanescent fiber optic sensor, Single- mode fiber