Picosecond pulse generation in optically pumped, ultrashort-cavity, InGaAsP, InP, and InGaAs film lasers

Ultrashort-cavity semiconductor film lasers made with InP, InGaAsP, and InGaAs have generated picosecond pulses over the wavelength range from 0.77 μm to 1.65 μm after optical pumping by an intense, 0.5 ps pulse at 0.625 μm. Each material composition operates over an energy range from just below the bandgap to more than 20 percent above the bandgap. For a given composition, pulse duration increases as wavelength increases; for different compositions, pulse durations increase as the bandgap energy decreases. Pulse durations range from 1.4 ps (for InP) to about 30 ps. Peak power is in the range of 1- 10 W. These unique properties of ultrashort-cavity film lasers are due to the combination of bandfilling caused by the intense photoexcitation and the ultrashort cavity, which provides widely spaced resonances to ensure single mode operation and also produces a short photon lifetime necessary for optical gain switching. The film lasers have a uniform, nearly Gaussian, spatial mode.