dc-electric-field dependence of THz radiation induced by femtosecond optical excitation of bulk GaAs

Abstract

We report a systematic study of the dc-electric-field dependence of THz radiation from a bulk GaAs sample optically excited by femtosecond pulses. The experimental results reveal that both displacement and transport currents contribute to THz radiation and the relative contributions are shown to be very sensitive to the dc electric field. This observation agrees qualitatively with a simulation based on a fully quantum-mechanical treatment of the transient photoconductive response of GaAs.