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 μm laser beating shows a 3-dB bandwidth of 700 GHz with radiation power at terahertz frequency of 0.1 μW 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.