Improved characteristics of a terahertz set-up built with an emitter and a detector made on proton-bombarded GaAs photoconductive materials

We report the coherent generation and detection of terahertz radiation from antenna-type devices made by using proton-bombarded GaAs photoconductive materials. Our combined emitter/detector set-up allows us to obtain a large bandwidth going from 0.1 up to 2 THz. We compare the performance of antenna emitters fabricated using mono- and multi-energy proton implantation in semi-insulating GaAs. Improved emission of terahertz radiation with a comparable bandwidth has been obtained using multi-energy proton implantation. Our results show that creating more defects in the optical absorption region gives rise to higher damage threshold biasing and larger saturation optical pumping power levels.