We have observed optical birefringence in liquids induced by single-cycle terahertz pulses with field strengths exceeding 100 kV/cm. The induced change in polarization is proportional to the square of the terahertz electric field. The time-dependent terahertz Kerr signal is composed of a fast electronic response that follows the individual cycles of the electric field and a slow exponential response associated with molecular orientation.
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This work was supported in part by ONR Grant. No. .
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