Abstract

While the application of dc and low frequency measurements to a high mobility electron gas is routine, there is a notable absence of high speed, real-time techniques and experiments to study directly dynamical effects e.g. in the quantum Hall regime. Recently, femtosecond laser techniques have been used to generate terahertz electromagnetic transients off semiconductor surfaces [1],[2], thereby producing a new possible source for such transient spectroscopy. The THz radiation propagates in the form of a well defined beam so that the conductance of a heterostructure can be measured on ultrafast timescale in a contactless way via a gated ultrafast photoconductive receiver. This method is directly sensitive to both the amplitude and the phase of the transmitted electric field in probing the induced currents.

© 1993 Optical Society of America