A solid state laser medium comprising at least one cooling element, i.e. cooling element, in contact with and alternating in series with at least one gain element. At least one cooling element and at least one gain element are joined at an interface having a center point, wherein the interface is physically modified at the interface such that the heat transfer coefficient at the interface decreases radially from the center point of the interface. The modified interface promotes thermal transfer from the gain element in the axial direction, in such a manner as to reduce thermal distortion affecting optical properties of the laser. Concentric radially disposed barriers to heat flow that hinder heat flow in the radial direction may be added within the gain element to further reduce thermal distortion within the laser medium.