Cryogenic Tm:YAG Laser in the Near Infrared

Thulium laser operation on the ³H₄–³H₆ transition at 823 nm has been demonstrated in bulk Tm:YAG by quasi-continuous-wave pumping with a fiber-coupled diode array at 782 nm. The prior demonstrations of this laser transition have been limited primarily to fluorozirconate glass host materials in waveguide configurations. Population trapping has been identified as an important consideration in the design and operation of lasers on this transition. The use of a crystalline host should enable both high peak and average power operation, and the basic principles discussed in this paper should be extensible to other crystalline hosts and room-temperature operation.