Reduction of spatial holeburning in a diode pumped Nd:YAG laser by the use of a composite laser crystal

Diode pumped solid-state lasers using the endpump geometry and proper focusing optics are generally easy to operate in TEM00 mode. However, to obtain single frequency operation steps should be taken to avoid spatial hole burning. Even unidirectional ring lasers may exhibit some spatial hole burning when pumping is applied near high reflectivity mirrors, an effect often termed residual hole burning.

Such residual hole burning may cause the laser to switch to multiple frequency operation at higher pumping levels. A generic ring laser geometry, which minimizes spatial hole burning is described.