Rectification and shift currents in GaAs

Abstract

We observe second-order rectification and shift currents in GaAs at 295 K using 150 fs pulses at 1.55 and 0.775 μm, respectively. For the same low pump intensity, 100 MW cm−2, the shift current density is 570 times larger than the rectification current density. At high intensity, the shift current is strongly affected by carrier screening and dephasing and is in phase quadrature with the rectification current. A maximum shift current density of 60 kA cm−2 is inferred for a pump intensity of 500 MW cm−2.