Anomalous optically generated THz beams from metal/GaAs interfaces

Abstract

We report the measurement of optically generated THz radiation from over ten different metal/GaAs interfaces. We observe an anomalous behavior in the THz beams emitted from these interfaces. In contrast to THz radiation generated at normal incidence where the amplitude of the THz signal decreases with increasing metal film thickness, at oblique incidence we observe increased THz emission with increasing metal thickness until reaching a maximum near 80 Å.