Heat loads in erbium-doped laser materials

In order to study the feasibility of power scaling in resonantly-pumped Er-doped lasers, the fractional heat loads of several laser materials were measured using direct thermocouple calorimetry under low-power illumination with ∼1550 nm light. A sample of 2% Er:YAG exhibited heat loads (relative to the absorbed power) of less than 5.4%, while samples of 1.1% Er-doped fluorophosphate glasses showed similar results, with heat loads of less than 5.3%. A fluorophosphate glass codoped with 2.2% Er and 2.5% Yb showed much higher heat loads of 11-14%, and samples of singly Er-doped and Er/Yb-codoped phosphate glasses both showed even higher heat loads in excess of 17%.