Ultrashort laser: Lasing in MBE GaAs layer with perpendicular-to-film optical excitation and emission

Lasing was observed in a 4.5 μm thick GaAs MBE-grown heterostructure (0.2 μm Al
0.42
Ga
0.58
As, 4.1 μm GaAs, 0.21 μm AlGaAs). The laser was driven by pulses from a mode-locked Ar laser (514.5 nm) with a maximum of 20 W peak power in 100 ps long pulses focused to 25 μm. The lasing occured along the pump axis within a cavity defined by the coated AlGaAs surfaces.