Enhanced terahertz emission from photoconductive antenna with ohmic contact electrodes biased by out-of-phase voltages

Terahertz emission power is one of the main obstacles for photoconductive antenna applications. In conventional photoconductive antennas, the electrical field distributes in a narrow area near to the anode, which limits the emission efficiency. A SI-GaAs antenna with AuGeNi ohmic contact electrodes was prepared by the present authors´ improved fabrication technology, and the electrical field distributes more evenly when one electrode was biased by a DC square wave pulse or two electrodes were biased by two DC square wave pulses with opposed phases. Compared with the conventional antennas, the terahertz emission efficiency of the antenna was improved by one order when biased by the out-of-phase voltages and illuminating the whole antenna gap to suppress the carrier screening and radiation screening.