A solid state laser comprises a laser element formed from crystalline, ceramic, glass ceramic, glass, or plastic material in the configuration of a rod or slab. The cooling capabilities of the rods or slabs are improved by the provision of internal bores or slots through which a coolant can flow, and/or by the provision of a modified cross-sectional profile whereby the cooling surface is increased and the distance between the interior regions of the rod or slab and the cooling surface is reduced. Alternatively, the cooling capacity of the laser system is improved by providing a rotating arrangement of laser material wherein only specific portions of the laser materials are subjected to pumping while other portions are cooling.