1 Watt femtosecond mid-IR Cr:ZnS laser

A room-temperature Kerr-Lens modelocked (KLM) Cr:ZnS laser generates <70 fs pulses duration (about eight optical cycles) with 5.6 nJ pulse energy and over 100 nm FWHM spectral width at 105-157 MHz repetition rates. The laser produces 1 W average output power at 20% optical efficiency, limited by the available Er: fiber pump. For further pulse energy scaling we also realized the chirped-pulse regime, with 0.8-2 ps pulse durations. The demonstrated applications of such mid-IR source range from extra- and intra-cavity spectroscopy to subharmonic OPO pumping. For environmentally-protected delivery we suggest and realize duration-preserving soliton delivery in a ZBLAN fiber. Further bandwidth increase is demonstrated by 2.0-2.8 mu m supercontinuum generation in a chalcogenide fiber.