Pulsed 2-micron lasers based on Tm3+-doped monoclinic double tungstate crystals

Abstract

Monoclinic crystals of Tm-doped KLu(WO4)2 were used to demonstrate pulsed laser operation near 2 μm. Passive Qswitching and passive mode-locking were the techniques employed to produce such laser pulses. For passive Qswitching we used an AlGaAs –based diode laser to pump the active elements and Cr:ZnSe and Cr:ZnS crystals as saturable absorbers. For passive mode-locking we used a Ti:sapphire laser as pump source and single-walled carbon nanotubes as saturable absorbers. In the former case, maximum pulse energies of 200 μJ for a pulse duration of 70 ns were achieved at a repetition rate of 3 kHz with Cr:ZnS saturable absorber, while in the latter case, ultrashort pulse durations of ~10 ps were measured with a maximum average power of 240 mW. In both laser regimes the oscillation wavelength was ~1945 nm.