GaAsBi Photoconductive Terahertz Detector Sensitivity at Long Excitation Wavelengths.

We report the terahertz frequency radiation detection using photoconductive antennas fabricated from molecular-beam-epitaxy-grown GaAsBi. We have estimated that the detector has the highest sensitivity when illuminated with 1.1- to 1.3-µm-wavelength femtosecond pulses. Electron scattering to higher conduction valleys takes place at shorter wavelengths; thus, we have determined the intervalley separation in the conduction band (0.26–0.29 eV). Though the sensitivity of GaAsBi detector at 1.55 µm decreases by about 40% compared with its maximum value, we have demonstrated a terahertz time domain spectroscopy system based on the femtosecond Er-doped fiber laser using this detector. [ABSTRACT FROM AUTHOR]