A fiber-optic temperature sensor based on optical thin films

Abstract

This contribution proposes a novel fiber-optic sensor developed for temperature measurement based on optical thin films. The sensing element is the optical multi-layer thin film coated at the fiber end. The sensor exploits the displacement of the optical cut-off edge occurring in optical thin films under the influence of temperature variation as a result of temperature-induced reflectivity shifting of cut-off edge at the same wavelength. The structure of the sensor and the measurement principle are described. The accuracy of the sensor can be improved by choosing the material of high refractive index temperature coefficient. The sensor has been tested operate from room temperature to 100 degrees centigrade. It shows good repetition in this sensor. The sensor also demonstrated good stability during extended temperature cycling tests.