Tunable cw solid state laser action in the 2-μm region

The 2-micron spectral region containing several strong molecular absorption bands such as carbon dioxide and water is reviewed. Tunable CW-laser action from resonantly pumped trivalent thulium is considered. A thulium-laser operating scheme is presented, and attention is given to the laser transition and laser cavity. The tuning range of a CW Tm:YAG laser at room temperature is analyzed, along with its output spectrum. Tunable laser performance in YAG codoped with trivalent thulium and trivalent holmium is investigated, and it is concluded that the output efficiency is better for the codoped laser than for the singly doped Tm(3+) laser in the range of 2.09 - 2.12 micron, but the overall tuning range and efficiency is better for the singly doped laser