NANOSECOND AND PICOSECOND 3-MU-M ERYSGG LASERS USING INAS AS PASSIVE Q-SWITCHERS AND MODE-LOCKERS

Recent results are reported using ultra-thin molecular beam epitaxy (MBE)-grown InAs epilayers on GaAs substrates as passive shutters for 3 mum Er:YSGG lasers (lambda = 2.8 mum). The laser photon energy is 27% higher than the InAs bandgap at 300 K and bleaching occurs due to a band filling effect with a fast recovery time of < 100 ps. Depending on the resonator geometry two modes of operation can be achieved: Q-switched with pulse durations of 35 ns and 5-6 mJ energy (TEM00 mode) and a Q-switched/mode-locked regime with an output in the form of a train of 30 pulses separated by a 4.3 ns interval, 0.25 mJ energy per spike and 30-50 ps pulse duration in a TEM00-mode. The latter are the shortest pulses obtained with this lasing medium to date.