Non-contact electro-optic sampling system in subpicosecond regime

An advanced external electrooptic sampling system is developed for use in high-speed electronic devices and circuit characterization of the subpicosecond regime. The system is designed on the basis of an electromagnetic field analysis, which clarifies system performance parameters such as sensitivity, temporal resolution, and invasiveness. One of the novel features of the system is sophisticated probe positioning over the circuit surface. An absolute distance accuracy of less than 1 μm and a resolution of less than 0.5 μm are realized, and measurement accuracy and reproducibility are improved. Another important feature is the precise positioning of multioptical beams without changing their optical path lengths, which enables accurate delay measurement of internal circuit nodes. A temporal resolution of less than 0.4 ps, a spatial resolution of 1 μm, and a voltage sensitivity of less than 1 mV/√Hz are achieved with this system. Generation and measurement of subpicosecond electrical pulses from a pulse-forming device are also demonstrated