Ultrafast optical Faraday effect in transparent solids

We predict a strong-field ultrafast optical Faraday effect, where a circularly polarized ultrashort optical pulse induces transient chirality in an achiral transparent dielectric. This effect is attractive for time-resolved measurements because it gives access to the non-instantaneity of the nonlinear medium response, and also because it represents relaxation of time-reversal symmetry by all-optical means. We propose probing the induced transient chirality with a weak linearly polarized ultraviolet pulse that is shorter than the near-infrared pump pulse. The predicted effects are ultrafast: the induced chirality vanishes for probe delays exceeding the duration of the near-infrared pulse. This opens up possibilities for applications in ultrafast circular-polarization modulators and analyzers.