Detection of up to 60 THz with an LT-GaAs photoconductive antenna

Summary form only given. The photoconductive (PC) antenna gated with ultrashort optical pulses played an important role to initiate the recent development of the terahertz (THz) opto-electronics. Owing to its high efficiency and good signal-to-noise ratio (SNR), the PC antenna has been used for the generation and detection of the coherent THz electromagnetic transients. However, the bandwidth of the PC antenna has been considered to be limited due to the finite carrier lifetime of antenna substrate semiconductors. The reported bandwidth of the PC antenna has been attained up to 7 THz. Therefore, recent interest in the broadband coherent detection higher than 10 THz has shifted to the electro-optic (EO) sampling technique. We report on the further expansion of the detectable bandwidth of the PC antenna. A broadband radiation was generated by using EO crystals as the emitter, and was detected with the PC antenna gated with 15-fs laser. The detected frequency extended to 60 THz. This is the highest frequency detected with a PC antenna so far reported.