Generation and detection of terahertz radiation up to 4.5 THz by low-temperature grown GaAs photoconductive antennas excited at 1560 nm

Generation and detection of terahertz radiation at 1560 nm based on low-temperature grown GaAs photoconductive antennas are demonstrated. The dependence of the DC photo current and terahertz peak amplitude on the illumination power are measured and found to follow a superlinear power law proposed for sequential charge carrier excitation via midgap states. A terahertz time domain spectroscopy system employing low-temperature grown GaAs photoconductive antennas pumped at 1560 nm reaches a bandwidth of 4.5 THz and a peak signal to noise ratio of 29 dB, while the reference measurement at 780 nm reaches 40 dB and a bandwidth of approximately 3 THz