High-Sensitivity Temperature Sensor Based on Photosensitive Polymer-Filled Silica Capillary Tube

A highly sensitive fiber-optic extrinsic Fabry-Perot interferometer (EFPI) is designed and demonstrated experimentally. The EFPI is composed of two sections of single mode fiber (SMF), a segment of silica capillary tube (SCT), an air cavity, and cured polymer which is filled in the SCT. The sensing part of structure of proposed EFPI is the air cavity, and the cured polymer has a modulating effect on the air cavity. Due to the high thermal expansion coefficient (TEC) of the polymer, the sensor exhibits a high sensitivity to temperature. Experimental results show that the temperature sensitivity of the proposed sensor reaches -2.88 nm/°C with a perfect linearity of 99.88%. Therefore, the proposed sensor with high-sensitivity, ease of fabrication and low cost is favorable to be used in high-accuracy temperature measurement.