Ultrafast middle-IR lasers and amplifiers based on polycrystalline Cr: ZnS and Cr: ZnSe

Transition-metal-doped II-VI semiconductors possess a unique blend of physical, spectroscopic, optical, and technological parameters. These materials enable high power lasers in important middle-infrared range. Furthermore, they combine superb ultra-fast laser capabilities with high nonlinearity and polycrystalline microstructure, which provides random quasi-phase matching. We developed flexible design of femtosecond polycrystalline Cr: ZnS and Cr: ZnSe lasers and amplifiers in the spectral range 2-3 mu m. We obtained few-opticalcycle pulses with a multi-Watt average power in a very broad range of repetition rates 0.071.2 GHz. We also report on efficient nonlinear frequency conversion directly in the polycrystalline gain elements of ultra-fast lasers and amplifiers including second harmonic generation with sub-Watt power and generation of an octave-spanning middle-infrared supercontinuum. (C) 2017 Optical Society of America.