Pump Radiation Transfer Methods

The efficiency in the transfer of radiation from the source to the laser element determines, to a large extent, the overall efficiency of the laser system. The optical design, besides providing good coupling between the source and the absorbing active material, is also responsible for the pump power distribution in the laser element which influences the uniformity, divergence, and optical distortions of the output beam.
In the development of solid-state lasers, many different optical designs have been employed to transfer the radiation from a light source to the active material.
Depending on the shape of the active material and the type of pump source used, one can broadly divide pumping geometries into systems in which the active material is side-pumped, end-pumped, face-pumped, or edge-pumped. Sideor transverse-, and end- or longitudinal-pumping refers to the orientation of the pump beam relative to the direction of the laser beam in the gain medium. Faceand edge-pumped slabs and disks differ in the directions in which waste heat is removed, and in the resulting directions and magnitudes of the thermal gradients relative to pump and output laser beam directions.