Ultrafast optics establishes metrological standards in high-frequency electronics

A measurement system is reported that allows for the complete characterization of high-speed oscilloscopes. The measurements are based on ultrafast optical methods, which are used to generate picosecond electrical pulses with photoconductive switches as test signals. The properties of the test pulses are determined by the electro-optic sampling method, which provides traceability to the unit of length and, hence, to the unit of time. The photoconductive switches combined with the electro-optic sampling system represent a primary standard in electrical pulse metrology. With the well-characterized pulses from this standard, the complex transfer function, the impulse and step response, as well as the intrinsic risetime of high-speed oscilloscopes are determined. Risetimes of 6-7 ps can be measured with an expanded uncertainty of 1.2 ps.