Leaky Radiation Mode Based Intensity Modulated Extrinsic PCS Fiber Refractometer Operating at the Dynamic Range of 20oC to 60oC

  • Dr. S. Venkateswara Rao, S. Srinivasulu


The loss of light radiation from optical fibers can be exploited to construct various kinds of sensors, with different geometries to measure several environmental parameters such as pressure, temperature, liquid level, liquid refractive index, liquid pH, antibodies, electric current, rotation, displacement, acceleration, acoustic, electric and magnetic fields, etc. In the present paper a refractive index sensor operating at the dynamic temperature range of 20oC to 60oC based on the process of leaky radiation at the region of sensing is described. A sensing zone is created in the sensor by joining a U-shaped glass rod having dimensions compatible with the fibers was used, between a light source operating at the wavelength of 660nm and a benchmark optical power meter. Light transmitting through the optical fiber was observed to be leaked in the form of leaky radiation, when the U-shaped glass rod immersed into a liquid mixture of refractive index less than the refractive index of the glass rod. The amount of leaky radiation modes of transmitted light is directly related to the refractive index of liquid mixture into which the glass probe is immersed. The variation of light reaching the detector was found to change as well with temperature of the liquid mixture, when maintained at different temperatures. The work was carried by varying the length of sensing zone by increasing the depth of immersion of U-shaped glass rod into the liquid mixture prepared with the combination of Toluene and Acetic acid, taking at different proportion, making the total volume is equivalent to 20ml.