Abstract
Optical pumping of a holmium:yttrium lithium fluoride (Ho:YLF) crystal with a 790-nm continuous-wave diode-laser array has generated 56 mW of 2.1 μm laser radiation with an optical-to-optical conversion slope efficiency of 33% while the crystal temperature is held at 77 K. The lasing threshold occurs at 7 mW of input power, and laser operation continues up to a crystal temperature of 124 K.