Abstract

The extraction of high power diffraction limited beams from CW pumped solid state lasers is of paramount importance for a number of scientific and industrial applications. Nd:YAG has been, up to now, the most widely used material, but it presents two serious drawbacks: a strong thermal lensing that limits the input power stability range and a thermally induced birefringence that prevents the resonator from working with fundamental mode spot sizes greater than about 1 mm even with large diameter rods. Nd:YLF is a good candidate for the generation of high power fundamental mode beams due to its greatly reduced thermal lensing effects and to its natural birefringence, which overwhelms the thermally induced one. However, the results so far reported^[1,2] all refer to lasers with rod diameter smaller or equal to 4 mm. Likewise, the selected operating wavelength has been so far limited to the 1053 line on account of the lower thermal focusing of the Nd:YLF at 1053 nm with respect to 1047 nm.

© 1992 IQEC