Capacitance free generation and detection of subpicosecond electrical pulses on coplanar transmission lines

By reanalyzing an earlier experiment to generate subpicosecond pulses using photoconductive switches (M.B. Ketchen, et al., Appl. Phys. Lett., vol.48, pp.751-753, 1986), it is shown that to first order, the sliding-contact generation site has no capacitance. This conclusion is further supported by a double sliding-contact experiment where, to first order, neither the generation nor the detection site has any capacitance. This result removes the parasitic capacitance of the electrical circuit as one of the major difficulties to short electrical pulse generation using photoconductive switches.>