Abstract

The generation of terahertz radiation from large-aperture, photoconductors is being pursued by a number of groups. ^1,2 The explanation for the terahertz generation process is still being debated, with two mechanisms under consideration: (1) a current surge picture where the radiation is due to the incoherent transport of the optically created carriers¹ and (2) a coherent mechanism where the radiation results from the inverse Franz Keldysh effect or electric-field-induced optical rectification.² For unbiased semiconductors a strong dependence of the intensity of the generated terahertz pulses on crystallographic orientation provides evidence that the second mechanism contributes to the radiation, especially under conditions of high optical excitation fluence.² In this paper we present, for biased semiconductor emitters, the dependence of the generated terahertz radiation on the cystallographic orientation of the bias field.

© 1993 Optical Society of America