기능성 폴리머가 코팅 된 광섬유 끝단을 사용하는 광섬유 센서 연구

Abstract

In this study, we propose a simple optical fiber sensor having a functional polymer-coated fiber-end surface. The reflected light from the surface of an optical fiber end was interfered with by light from the surface of the coated material. This produces an interference pattern in the spectral domain. The main idea behind the optical fiber sensor is based on the multi-reflection interference phenomenon that occurs in the optical thin film layer. We propose two fiber sensors an ultraviolet (UV) light sensor and a temperature sensor that employ a multi-reflection interference scheme that works in conjunction with optical fibers. For the UV light sensor, an azobenzene polymer is used as a UV light responsive material coated on the end surface of a single mode fiber. The UV light changes the reflective index and volume of the polymer material. It also changes the optical path length of light propagating through the coated material. Because the phase of the interference pattern is linearly proportional to the optical path length, the UV-induced phase change of the pattern provides information about the UV light. For the temperature sensor, an optical adhesive is used as a functional polymer to measure the phase change of the interference pattern with the changing temperature. The proposed fiber sensors can be applied to many industrial fields that detect UV rays and measure temperature. In addition, the sensing scheme of the multi-reflection interference can be used for various sensors such as those for pressure, radiative power, and humidity in combination with polymers responsive to physical quantities.