Ultrafast magneto-optic sampling of picosecond current pulses

We report the demonstration of a magneto-optic sampling technique that allows for the detection of picosecond electrical pulses propagating down a microstrip transmission line. A unique feature of the method is that it directly measures the current in ultrashort electrical pulses. The technique is based on time-resolved detection of the magneto-optic Faraday effect in a Bi-substituted yttrium-iron-garnet (Bi-YIG) film. The detailed magnetic response is found to be in excellent agreement with the Bloch-Bloembergen equations. The bandwidth of the sampling system has been demonstrated to scale with the ferromagnetic resonance frequency up to 82.3 GHz, with a potential for increase towards 1 THz. (C) 1996 American Institute of Physics.