High-Intensity THz Radiation From a Large Interdigitated Array Photoconductive Emitter.

We report on the performance of photoconductive THz emitters based on an interdigitated metal-semiconductor-metal finger structure. In every second period of this structure optical excitation is inhibited. Thus carrier acceleration is unidirectional over the whole device area and the emitted THz radiation interferes constructively in the far field. Excitation with amplified laser pulses leads to THz amplitudes of 6 kV/cm. Saturation of the emission due to screening of the bias field was observed for excitation densities in the 1018 cm−3 range. However, since the emitter concept is scalable to large areas, the THz emitter offers large potential for further increase of the emitted THz field amplitude. [ABSTRACT FROM AUTHOR]