Abstract

Power-scaling of two-micron solid-state lasers to meet the demands of applications such as LIDAR and mid-infrared generation via nonlinear frequency conversion is an area which has attracted growing interest over recent years. In this paper we describe a simple strategy for achieving high power operation of a Ho:YAG laser. Singly-doped Ho:YAG is an attractive laser material for operation in the two-micron wavelength regime, with lower upconversion losses, and hence a longer effective energy storage time (~8ms) than for Tm-sensitised Ho:YAG. Furthermore, it has an operating wavelength (~2.1µm) which is attractive for LIDAR applications due to its relatively high atmospheric transmission. Unfortunately, Ho:YAG has no absorption band in the 780nm-980nm spectral region and hence cannot be pumped directly with commercially available high-power GaAlAs and InGaAs diode lasers. One solution to this problem is to pump the Ho:YAG laser, in-band, with a diode-pumped Tm laser. Recent work by Budni et al [1] has demonstrated high-power operation of Ho:YAG by direct pumping with diode-pumped Tm:YLF and Tm:YALO lasers. Here we describe an alternative approach for power-scaling of Ho:YAG via intracavity, in-band, pumping in aTm:YAG laser.

© 2000 IEEE