Cr:Er:Tm:Ho:yttrium aluminum garnet laser exhibiting dual wavelength lasing at 2.1 and 2.9 μm: Spectroscopy and laser performance

Over 1.0 J of 2.1 μm laser energy and over 0.5 J of 2.9 μm laser energy have been demonstrated in a single flashlamp pumped solid state laser material, specifically Cr:Er:Tm:Ho:YAG. Flashlamp pumped laser operation of Ho:YAG at 2.1 μm and Er:YAG at 2.9 μm in various host materials is well known. We have developed an innovative laser system that operates at each of these wavelengths independently or simultaneously in a single solid state laser material with performance comparable to single wavelength systems Er:YAG and Cr:Tm:Ho:YAG. Variation of the flashlamp pump pulse length provides a method to discriminate between lasing at 2.1 and 2.9 μm. This effect results from Er→Tm→Ho energy transfer, the short lifetime of the upper lasing manifold in Er, the I11/24 manifold, and the relatively long upper laser level lifetime in Ho, the I75 manifold. This simple tuning method of achieving two widely separated wavelengths without the use of optical tuning elements has potential applications in remote sensing and medical lasers.