Optically-based testing of circuits and devices

Summary form only given. The progress of two of the principal optically based techniques for the testing of circuits and devices-electrooptic and photoconductive sampling-was discussed. The various embodiments of the optically based measurement techniques have bandwidths that approach or exceed 1 THz. They have been used to perform network analysis for the small-signal characterization of HEMTs (high electron mobility transistors) and other high-frequency devices, acquiring S-parameters up to frequencies greater than 100 GHz. Furthermore, since single-picosecond-risetime step functions with significant voltage amplitudes can be routinely generated using short laser pulses, large-signal switching measurements have also been made using optical methods.<>