Simultaneous Interrogation of Refractive Index at Various Temperatures Employing a Passive Fiber Optic U-Shaped Sensor Using a Tunable Light Source

Abstract

 Fiber optic sensors have become more popular over the conventional sensors like mechanical sensors, chemical sensors, electrical sensors and bio-medical sensors etc, due to their advantages with reference to sensitivity, size, weight, cost, safety and security, reliability, longevity and flexibility in implementation and so on and so forth, for the last three and half decades since their inception around 1970. An advanced sensor for detecting changes in chemical parameters comprises a sensing U-shaped glass rod as core surrounded by a sensitive cladding, the absorption coefficient which various due to the changes in chemical parameters, when applied as the cladding and a pair of two transmissive optical fibers having a core surrounded by an insensitive cladding for connecting to a remote light source and a detector. The changes in the output optical power with respect to the changes in the concentration of the liquid cladding i.e. Toluene and tert-Butanol surrounding the U-shaped glass rod used to determine the refractive index simultaneously at the operating wavelengths of 630nm, 660nm, 820nm and 850nm, by employing a tunable light source at different temperatures.