Diode and fibre pumped Cr 2 þ : ZnS mid-infrared external cavity and microchip lasers

Demonstrations of CW and pulsed microchip lasing in Cr2þ:ZnS and Cr2þ:ZnSe crystals are reported. Slope efficiencies up to 53% with output power up to 150 mW for CW and energy up to 1 mJ for pulsed pumping were achieved. Two compact diode and Er fibre laser directly pumped external cavity Cr2þ: ZnS lasers are also described.