Abstract
We present a numerical model to simulate the influence of thermal effects on the laser output power in holmium-doped fiber amplifiers. It aims to estimate heat generation and output power more precisely, especially crucial for high power operation. The thermo-optical model includes optical effects like pair-induced quenching (PIQ), which heats the fiber, and temperature-dependent parameters like the holmium cross sections. We apply the model to a holmium-doped fiber amplifier, developed by the Fraunhofer Institute for Laser Technology (ILT), in the Interreg project E-TEST. The computed laser efficiency agrees well with the experimental data. For an uncooled active fiber pumped at 1950 nm with 25 W, we compute a rise in fiber temperature of up to 78 K, which results in a temperature-induced decrease in signal power at 2095 nm of more than 14 % to approximately 6 W, compared to the signal power computed with a solely optical simulation.