Abstract

We describe a photoconducting antenna array, a novel optoelectronic device for optically generating and electrically steering a sub-millimeter wave. An array of 32 photoconducting antennas, formed by a pattern of parallel electrodes, was deposited on semi-insulating GaAs. The voltage applied to the electrodes varied sinusoidally across the 3.2 mm array. Under optical illumination, the strengths of the photocurrent elements between adjacent electrodes also had a sinusoidal distribution and the array radiated a sub-millimeter wave. To produce directional radiation, the array was illuminated with a train of four optical pulses spaced 2 picoseconds apart. The array emitted a burst of radiation at 500 GHz which could be electrically steered in free space by varying the period of the sinusoidal bias on the electrodes. For the array used, the estimated radiation width was 10 degrees. When the array was illuminated with a single optical pulse, it generated broadband radiation. In this case the spatial bias pattern on the electrodes was mapped into the temporal waveform of the radiated field. When a sinusoidal bias pattern was applied to the electrodes, the wavelength of the radiation detected in the far field could be scanned from millimeter-wave to microwave frequencies by changing the bias period.

© 1990 Optical Society of America