Uniform u-shaped glass rod based fiber optic refractometer: Influence of temperature on refractive index of liquids

The influence of temperature on the refractive index of liquids using a uniform U-Shaped glass probe based fiber optic evanescent wave absorption sensor is investigated experimentally. The extrinsic optical fiber sensor having high sensitivity and a linear dynamic range is proposed in the present paper. The U-Shaped uniform glass probe is used to achieve high sensitivity and while the linear dynamic response is obtained by preventing the surface reactivity of the solute molecules of the absorbing fluid with the silica glass rod. Two PCS fibers are connected to both ends of the U shaped glass rod. The other end of the input fiber is connected a light source of 630nm wavelength and output fiber is connected to a power detector. Light from the source is launched into the input fiber and the power reaching the detector is recorded. The changes in the power levels are noted from the variations in intensity reaching the detector due to the influence of the temperature on the refractive index of active medium surrounding the sensing probe. The sensor can be easily constructed and a great deal of repeatability and reproducibility has been obtained in the experimentation.