The spectral response of a low-temperature-grown GaAs photoconductive (PC)
antenna is compared with that of the electro-optic sampling technique for t
he frequency region up to 40 THz. The spectral response of the PC antenna f
or broadband detection is found to be determined by the temporal profile of
the number of photocarriers injected by ultrashort optical gate pulses. (C
) 2001 American Institute of Physics.