Terahertz time-domain-spectroscopy system based on femtosecond Yb:fiber laser and GaBiAs photoconducting components

We describe a terahertz time-domain-spectroscopy system that is based on photoconductive components fabricated from low-temperature-grown GaBiAs epitaxial layers and activated by femtosecond 1.03 mu m pulses emitted by an Yb:fiber laser. Experiments performed with the laser pulses of different durations have evidenced that the spectral range of the system is limited by the photoexcited carrier lifetime. The optical to terahertz conversion efficiency of the system exceeds 10(-4) with the usable spectral range of about 3 THz in the case of 170 fs excitation pulses. (C) 2010 American Institute of Physics. [doi:10.1063/1.3458826]