Non-conventional Method of Determination of Refractive Index using Fiber Optic U-shaped Glass Sensor in the Study of Certain Biological Fluids

Abstract

Uniform U-shaped glass probe based extrinsic optical fiber refractive index sensors have tremendously received attention in the research and development across the world in the recent past. The U-bent probe as an extrinsic element in the design of optical fiber sensors provides the enhancement in the sensitivity at higher orders in the investigation of refractive index of various liquids including certain biological fluids. In the present work, the U-shaped probe with definite dimensions connected between a source of 660nm and a bench mark light detector, becomes a clad removed part of the sensor and acts as the sensing zone of the sensor. By immersing the glass rod into liquid mixtures of various indices of refraction, the power reaching the detector was recorded corresponding to the refractive index of liquid mixtures. Plotting the graph by taking refractive index on X-axis and power output on Y-axis a calibrated curve was drawn, which can be used to determine refractive index of various liquids including certain biological fluids. This method of measuring refractive index of liquids is a novel and nonconventional, which was completely different from the conventional methods which were popular in recent times of determination of refractive index of liquids.