Abstract:We reported the observation of intense ultrashort electric pulses generated by a novel nearly-filled-gap nonuniform illumination (NFGNI) excitation scheme. This NFGNI scheme differs from conventional nonuniform illumination in that 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 NFGNI of 100 fs laser pulses on sliding-contact photoconductive switches (PCS) fabricated on low-temperature-grown (LT-) GaAs, electric pulse correlation with 187 fs FWHM, which corresponds to a 3dB bandwidth of 1.1 THz, was observed. To our knowledge, these are the shortest electric pulses ever reported in the literature. Moreover, these electric pulses were found three times stronger than those generated with filled-gap illumination. Bias, wavelength, and pump power dependencies are discussed.