Electrode width dependent performance of THz photoconductive emitters

Strip line geometries are important for modern large area photoconductive terahertz (THz) emitters with interdigitated electrode designs. Strip line structures with varying electrode widths have been studied for photoconductive terahertz emission. The amplitude of the emitted THz pulse depends linearly on the electrode width if the width is much smaller than the THz wavelength, whereas for wider electrodes, the THz emission shows saturation-like behavior with respect to the electrode width. Strip line width acts as antenna length in such emitters. Narrower strip line structures (less than 20 µm) acts as a short dipole antenna and hence gives a linear dependence of the radiated THz field on the strip line width.