Ultrabroadband terahertz radiation from low-temperature-grown GaAs photoconductive emitters

Terahertz radiation was generated with a biased and asymmetrically excited low-temperature-grown GaAs photoconductive emitter, and characterized with a 20-mum-thick ZnTe crystal using free-space electro-optic sampling. Using a backward collection scheme, we obtained terahertz radiation with frequency components over 30 THz, the highest ever observed for photoconductive emitters. We present spectra over the whole frequency range between 0.3 and 20 THz, demonstrating the use of this source for ultrabroadband THz spectroscopy. (C) 2003 American Institute of Physics.