[[abstract]]Terahertz (THz) electric pulses generated by nonuniform illumination excitation in a nearly filled-gap configuration were observed. In this scheme, the excitation beam is focused to a spotsize only slightly smaller than the spacing between the transmission lines and is located symmetrically within the gap. With 100 fs laser pulses excitation on sliding-contact photoconductive switches fabricated on low-temperature-grown GaAs, electric pulse correlation with 190±20 fs full width at half maximum, which corresponds to a 3 dB bandwidth of 1.1 THz, was observed. Moreover, electric pulses with three times larger peak amplitude than those generated with filled-gap illumination from In coplanar striplines were observed. Bias, wavelength, and pump power dependencies were investigated.
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