Generation of tunable picosecond pulses from a bulk GaAs laser

Tunable picosecond pulses have been generated from a bulk GaAs crystal which supports a gain column 1 cm in length. Using two-photon absorption as the means of excitation, deep penetration of the pump intensity further increases the volume of the gain medium and enables the generation of pulses with peak power in the megawatt range. The output wavelength of the GaAs emission is tunable by changing the temperature of the crystal. A tuning range covering 840-885 nm has been achieved over a temperature range from 97 to 260 K. The variation is approximately linear with a slope of ∼0.26 nm/K. It has also been observed that the intensity of the output is highest when the temperature of the crystal is at its lowest, 97 K in our experiment.