An ultra-wide bandwidth photomixer with down conversion at terahertz frequency

We report on the development of an-ultra-broad band photoconductive detector, based on low-temperature-grown GaAs, vertically-integrated with terahertz spiral antennas. Velocity overshoot was expected in the photo-response facing the dramatic decrease in conversion efficiency due to a very short carrier lifetime. Photomixing experiments with two optical 0.8 /spl mu/m laser beating shows a 3-dB bandwidth of 700 GHz with radiation power at terahertz frequency of 0.1 /spl mu/W under moderate optical pumping and bias voltages. Preliminary results are also reported at long wavelengths taking advantage of the sub-gap absorption tail for non-annealed samples.