Sensing Characteristics of Fiber Fabry-Perot Sensors Based on Polymer Materials

A simple optic-fiber Fabry-Perot (FP) sensing technique was proposed and experimentally investigated by using polymer material to connect the ends of two singlemode fibers. Four different polymer materials (benzocyclobutene (BCB), UV88 (Relentless, China), Loctite3525 (HenKel, Germany), and NOA68 (Norland, USA)) filling the FP cavity were used to comparatively study the sensing performance of temperature, strain and refractive index. The result shows that the FP sensor with BCB has excellent repeatability with good linear response to temperature in a wide range from room temperature to 250 degrees C, which is much larger than that of other three materials (<90 degrees C), while UV88 with a cost of less than 1/10 of the other three polymer materials has the best sensitivity to strain and temperature. In addition, the FP sensor was firstly applied to measure ultraviolet (UV) light intensity. The test results demonstrate that the proposed FP sensor structure has a good linear response and repeatability to UV intensity for all four polymer materials, and Loctite3525 has the highest sensitivity (0.0087 nm/(mw/cm(2))) and the best repeatability among the four polymer materials.