Abstract: A conversion efficiency of 42% and slope efficiency of 60% relative to absorbed pump power are obtained from a continuous wave diode-pumped Tm, Ho:YLiF.sub.4 laser at 2 .mu.m with output power of 84 mW at a crystal temperature of 275 K. The emission spectrum is etalon tunable over a range of 7 nm (16.3 cm.sup.-l) centered on 2.067 .mu.m with fine tuning capability of the transition frequency with crystal temperature at a measured rate of -0.03 cm.sup.-1 .K.sup.-1. The effective emission cross-section is measured to be 5.times.10.sup.-21 cm.sup.2. These and other aspects of the laser performance are disclosed in the context of calculated atmospheric absorption characteristics in this spectral region and potential use in remote sensing applications. Single frequency output and frequency stabilization are achieved using an intracavity etalon in conjunction with an external reference etalon.