Gigahertz modulation of tunable terahertz radiation from photomixers driven at telecom wavelengths

Here, we report the gigahertz-rate modulation of a tunable terahertz carrier. Terahertz radiation, tunable from 300 GHz to 1.2 THz, is generated by mixing two telecom lasers with an offset frequency in an ultrafast In0.53Ga0.47As photoconductive device coupled to a broadband antenna. The microwave modulation applied to the telecom lasers is directly transferred to the terahertz carrier. A maximum modulation rate of 20 GHz has been achieved, and the bandwidth is independent of the carrier frequency.