The use of tapered fibers in an intensity based single mode temperature sensor

In this paper a single mode fiber optic sensor for monitoring temperature changes has been modeled, built and evaluated. The fiber optic sensor has been developed using a biconically tapered single-mode optical fiber. The tapered fiber is mounted in a groove cut within a polymer rod and straight clamped at the rod edges. The sensor is activated by heating it at a reference temperature according to the desired range of the sensor. The induced bending is the effect produced by expansion or contraction of the polymer rod. The activation temperature and the taper dimensions play a key role in the performance of the designed sensor. For the same taper length, a larger activation temperature determines a higher total loss in the taper. Additionally, a decrease in the taper length over the same temperature range with the same activation temperature will establish an increase in the total loss of the taper. The experimental and simulated results showed a good consistency in the fabrication of the designed sensors. The main features of the designed fiber optic sensor are good repeatability, wide dynamic range, low weight, small size and low cost.