Thermal analysis of diode-pumped femtosecond-laser-written Pr:LiLuF4 waveguide lasers

In this work we report a thermal stress test executed on high efficiency diode pumped waveguide lasers based on Pr:LiLuF4. 4 . Numerical simulations have been performed to estimate the core temperature. We demonstrated that no modifications in the output power, 275 mW at 604 nm and 310 mW at 721 nm, and in the bulk-level slope efficiency, 40% at 604 nm and 50% at 721 nm, have been observed with an estimated core temperature of 70 degrees C. We also executed stability measurements of the free running laser in thermally severe conditions, demonstrating output power fluctuations of mechanical origin as low as 10% of the peak value.