A wide temperature tunable fibre laser using a chirped grating and a type IIA fibre Bragg grating

Abstract

A fibre laser sensor has been developed to operate over a wide temperature range from room temperature to 440 °C, where the laser cavity has been formed using a combination of a chirped grating and a type IIA fibre Bragg grating (FBG), enclosing a length of erbium doped fibre as the active gain medium. A FBG stabilized 1480 nm laser diode was employed as the pump source to achieve laser oscillation associated with the type IIA Bragg grating wavelength on the wavelength band around 1550 nm. The broadband-chirped grating was used as one of the cavity end reflectors to achieve temperature-tunable laser action for sensing applications over a wide range. The sensitivity of the sensor was found to be 13.94 pm °C−1 with a root mean square error of 8.85 °C. The primary advantage of this laser-based sensor over passive optical fibre sensors is the significant improvement in both the signal-to-noise ratio and the narrow linewidth of the laser signal, making it especially well suited to multiplexing situations.