We characterize the manner in which the carrier-envelope phase of ultrashort pulses can control quantum interference of injected photocurrents in low-temperature-grown gallium arsenide. We verify the predicted linear and square-root dependences of the generated current on the average optical powers of the low (nu) and high (2nu) frequency wings of a pulse spectrum, respectively. When scanning the time delay between these two colors, the signal amplitude exhibits a temporal width of 72 fs. The generated signal behaves as an ideal current source for loads below ∼100 kOmega. This behavior allows us to increase the signal detection bandwidth from 25 kHz with a voltage amplifier to 830 kHz by use of a transimpedance amplifier; higher bandwidths are possible. We discuss how transimpedance amplification could also enable the quantum-interference photocurrent signal to be measured by use of materials with longer carrier lifetimes, such as intrinsic GaAs.
© 2005 Optical Society of America
(120.5050) Instrumentation, measurement, and metrology : Phase measurement
(190.5970) Nonlinear optics : Semiconductor nonlinear optics including MQW
(320.7100) Ultrafast optics : Ultrafast measurements
Peter A. Roos, Xiaoqin Li, Jessica A. Pipis, Tara M. Fortier, Steven T. Cundiff, Ravi D. R. Bhat, and John E. Sipe, "Characterization of carrier-envelope phase-sensitive photocurrent injection in a semiconductor," J. Opt. Soc. Am. B 22, 362-368 (2005)