Frontiers of Mid IR Lasers Based on Transition Metal Doped Chalcogenides
Enabling broad tunability, high peak and average power, ultrashort pulse duration, and all known modes of laser operation transition metal (TM) doped II VI chalcogenides are the materials of choice for direct lasing in the mid IR. The host materials feature broad infrared transparency, high thermal conductivity, low phonon cutoff, low optical losses, and are available as either single crystals or polycrystalline ceramics. Doped with TM ions, these media exhibit a four level energy structure, the absence of excited state absorption, as well as broad absorption and emission bands. Doped single crystals of high optical quality are difficult to grow; however, the advent of postgrowth diffusion doped ceramics has resulted in significant progress in laser development. Here, we summarize recent experimental laser results on Cr and Fe doped II VI chalcogenides providing access to the 1.8 6 mm spectral range with a high >60% efficiency, multi Watt level [140 W in continuous wave (CW) output powers, tunability of >1000 nm, short pulse <16 fs) multi Watt oscillation, and multi Joule output energies in free running and gain switched regimes. We also review recent results on hybrid fiber bulk (Er fiber/Er:YAG, Tm fiber: Ho:YAG/YLF) systems combining high efficiency of CW fiber lasers with high pulse energies of bulk materials and serving as pump sources of gain switched Cr:II VI lasers.
IEEE Journal of Selected Topics in Quantum Electronics