Abstract

We report on a novel phenomenon: an intense circularly polarized infrared laser pulse induces a transient chirality in an achiral transparent dielectric. In contrast to the well-known optical Faraday effect in atomic vapours [1], this effect occurs far from resonant transitions—we consider the case where a uniaxial dielectric crystal (sapphire) is transparent to light. We show how the build-up and decay of the induced chirality can be probed with an ultrashort linearly polarized ultraviolet pulse that is shorter than the infrared pulse. By simulating electron dynamics in three spatial dimensions, while working in a basis of Kohn-Sham orbitals, we show that the nonlinear interaction significantly changes the polarization direction and the ellipticity of the propagated probe pulse for pump fields as strong as 𝐹_IR~1 V/Å. In this parameter regime, nonperturbative phenomena become important. Such effects include interband tunnelling and the Franz-Keldysh effect, which are responsible for complex electron dynamics and essentially noninstantaneous polarization response [2,3].

© 2017 IEEE