Temperature sensing characteristics of tapered Tm3+-doped fiber amplifiers

We numerically analyze the temperature response of a tapered Tm3+-doped fiber amplifier. The analysis includes a redefinition of the coupled pump and signal propagation equations in order to introduce different longitudinal shapes of the tapered doped fiber and the temperature dependence of the absorption and emission cross sections of the Tm3+ ions under different pump schemes. It was found that the temperature sensitivity of the normalized amplified signal was 2 × 10−3/°C for 1 W of pump power and 3 m of doped fiber length, using a parabolic taper in a co-propagating pump scheme. This sensitivity can be increased by at least 5 times if we adjust the design parameters of the fiber amplifier using fiber lengths shorter than 1 m and pump powers lower than 300 mW. Our results contribute with new information for the development and optimization of tapered fiber amplifiers doped with other rare earths, and novel designs for doped-fiber temperature sensors.