Abstract

A normal mode alexandrite laser has been used as a laser diode simulator for pumping a Tm:Ho:YAG laser to investigate performance as a function of pump laser pulsewidth. An end pumped geometry utilizing several 4 mm long Tm:Ho:YAG crystals in a standing wave resonator and various output couplers was used to determine threshold and slope efficiencies. Output coupler reflectivities varied from 0.7 to 0.99, and the pump pulse-width, varied from 200 μs to 650 μs. A maximum slope efficiency in terms of the absorbed energy of 0.4 was observed for all pulse-widths. However, the output coupler reflectivity for which this maximum was achieved was pulse-width dependent. A significant reduction in slope efficiency was observed for the lower reflectivity output couplers. This reduction was more severe for the longer pump pulse-widths and has been attributed to increased upconversion losses. Experimental details and a theoretical discussion will be presented.

© 1992 Optical Society of America