Terahertz generation and detection of 1550-nm-excited LT-GaAs photoconductive antennas

Terahertz generation and detection is the key means to explore terahertz spectrum, one of which is the application of photoconductive antenna. In this study, a low-temperature gallium arsenide (LT-GaAs) epitaxial wafer antenna and an LT-GaAs thin-film antenna were fabricated. The LT-GaAs epitaxial wafer antenna was fabricated using an epitaxial wafer composed of LT-GaAs, AlAs,GaAs, and semi-insulating GaAs. An LT-GaAs thin film was obtained by etching the AlAs layer in the epitaxial wafer and then transferring it to a clean silicon wafer to fabricate the LT-GaAs thin-film antenna. The LT-GaAs epitaxial wafer and thin-film antennas were used as the generation and detection antennas, respectively. The two antennas were directly aligned at a distance of 2 mm from each other and placed into a self-made measurement system for detection. A THz spectrum of approximately 2.5 THz was obtained under 1550-nm laser excitation, thus verifying the antenna performance.