Ultra-broadband coherent terahertz spectroscopy using asymmetric excitation of photoconductive structures

摘要

We report recent progress in the generation of ultra-broadband (>14.0 THz) coherent terahertz (THz) radiation, with high dynamic signal-to-noise ratio (>1000), using asymmetric excitation of carriers in biased low-temperature-grown GaAs (LT-GaAs) photoconductive structures. The generated ultrashort THz temporal wave form is characterized by both free space electro-optic sampling (using 20-/spl mu/m-thick ZnTe and 150-/spl mu/m-thick GaP crystals) and a LT-GaAs photoconductive receiver. Spectral features originating from optical phonon resonances in the emitter and detector materials are observed in this frequency range. The use of this system to probe dielectric properties of materials is also discussed.