Thermal behavior and management of membrane external-cavity surface-emitting lasers (MECSELs)

Thermal simulations based on the finite-element method provide an estimation of what the heat management in membrane external-cavity surface-emitting lasers (MECSELs) is capable of: When considering diamond and SiC heat spreaders, double-side cooling (DSC) leads to gain membrane temperatures that are about a factor two lower than with single-side cooling (SSC). For the thermally worse conductive sapphire, the temperature benefit from DSC can be up to four times lower than with SSC. Diamonds as heat spreaders are recommended over SiC if the power for pumping the gain membrane is three times larger, for instance at 30W at a pump beam diameter of 180 μm. Sapphire can be favored over SiC if the pump power is about five times lower, for instance at 2W. Due to the limited lateral heat flow activity of sapphire, a smaller pump beam diameter of 90 μm is suggested. A super-Gaussian pump beam can be used instead of a Gaussian pump beam to lower the gain membrane maximum temperature by a factor of three. Double-side pumping becomes significantly more important as soon as the gain membrane gets thicker than 1 μm.