OBSERVATION OF COHERENTLY CONTROLLED PHOTOCURRENT IN UNBIASED, BULK GAAS

We demonstrate room temperature coherent generation and control of a d irectional photocurrent in bulk GaAs via simultaneous one- and two-pho ton interband absorption processes using phase-related 1 ps or 175 fs pulses at 0.775 and 1.55 mu m. Electrical currents generated in low-te mperature-grown (LT) and normal bulk GaAs are collected via gold elect rodes. Current densities as high as 3 nA/mu m(2) in LT-GaAs are measur ed for injected carrier densities as low as 10(14) cm(-3) and for peak irradiances of 18 MW cm(-2) (1.550 mu m) and 3 kW cm(-2) (0.775 mu m) .