Abstract

Diode pumped solid-state lasers using the end-pump 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 shown in Fig. 1. Different designs have been tested to obtain specific properties. The laser crystal is a 7mm long 1.1 % atmNd:YAG crystal with plane parallel end faces. One end face is coated for high reflectivity at the laser line 1064 nm and high transmission for the pump laser frequency at 809 nm. The other face is AR coated. The pump laser is focused to a 200 mm spot size and pumping is applied through the end mirror. A ring cavity with a large angular separation of 13° internal at the end mirror is formed by means of the prism mounted with Brewster’s angle incidence. A curved output mirror forms the third component of the laser.

© 1996 Optical Society of America