Thermal Management in 2.3- μm Semiconductor Disk Lasers: A Finite Element Analysis

Finite element analysis is used to study heat flow in a 2.3-mum semiconductor disk laser (or vertical-external-cavity surface-emitting laser) based on GalnAsSb-AlGaAsSb. An intra-cavity diamond heatspreader is shown to significantly improve thermal management-and hence power scalability-in this laser compared to the substrate thinning approach typically used in semiconductor disk lasers operating around 1 mum. The parameters affecting the performance of an intracavity heat-spreader are studied in the context of a 2.3-mum semiconductor disk laser: the thermal impedance at the interface between the semiconductor gain material and the heatspreader is found to be much more important than the mounting arrangements for the gain-heatspreader composite; power scaling with pump spot radius-increasing the pump power at constant pump intensity-is found to be intrinsically limited; and the pump wavelength is predicted to have less affect on thermal management than might be expected. Direct pumping of the quantum wells is found to significantly reduce the temperature rise per unit pump power.