Terahertz Kerr effect

TL;DR

This paper reports the observation of optical birefringence in liquids induced by intense single-cycle THz pulses, revealing both electronic and molecular orientation responses to the electric field.

Contribution

It demonstrates the first measurement of THz-induced birefringence in liquids, distinguishing electronic and molecular orientation effects with high field strengths.

Findings

Optical birefringence proportional to square of THz field

Fast electronic response following THz cycles

Slow molecular orientation response

Abstract

We have observed optical birefringence in liquids induced by single-cycle THz pulses with field strengths exceeding 100 kV/cm. The induced change in polarization is proportional to the square of the THz electric field. The time-dependent THz 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.