Abstract

Diode-pumped solid-state lasers at 2 gm have been demonstrated using Tm³⁺-doped gain media and Tm³⁺-sensitized, Ho³⁺ gain media pumped at 0.79 gm. Both of these lasers have significant drawbacks: the Tm³⁺ systems have high saturation fluence, —50 J/cm², and thus are prone to damage under Q-switched operation, and the sensitized Ho³⁺ lasers have lower saturation fluence but low extraction efficiency under Q- switched operation because of upconver- sion and stored energy partitioning between Tm³⁺ and Ho³⁺. Ho³⁺ lasers pumped at 1.9 gm offer the prospect of improved short-pulse performance relative to the other systems because they have the lower saturation fluence of Ho³⁺ and have no stored energy partitioning. Reduced upconversion is expected and the heat dissipated in the gain medium per unit absorbed pump power is reduced by a factor of three to five based on quantum defect alone. A Ho:YAG laser has been demonstrated previously by intracavity pumping with a Tm:YAG laser at 2.01 girt,¹ and preliminary results using a single GalnAsSb-diode-laser pump source at 1.9 gm have been reported.² Here, we report on power scaling of a 1.9-gm-diode-pumped Ho:YAG laser to the 0.5-W power level.

© 1994 Optical Society of America