Propagation characteristics of picosecond electrical transients on coplanar striplines

Using a cryogenic electro-optic sampling technique, we have studied the transient propagation characteristics of superconducting and normal indium lines in the picosecond regime. Transient dispersion effects, including increased rise time and increased pulse width, the introduction of ringing on the waveform, and a novel ‘‘pulse sharpening’’ were observed. A model that takes into consideration the effects of modal dispersion and superconducting complex conductivity was established, and an algorithm was developed that accurately describes all of the experimental findings.