Abstract

Recently, terahertz radiation has been observed by femtosecond optical excitation of surface depletion layers of semiconductors [1]. Two physical models have been proposed to explain the origin of this radiation. One of them attributes the THz radiation to the time-dependent transport current [1]. The other proposes that the displacement current generated by instantaneous creation of polarized electron hole pairs causes radiation [2]. In a MQW structure, since carrier transport is prohibited by quantum confinement, THz radiation induced should be caused only by the displacement current [3]. In bulk material, however, the physical picture gets complicated since both the transport and the displacement current exist and contribute to THz radiation.

© 1993 Optical Society of America