Subcycle-resolved probe retardation in strong-field pumped dielectrics.

The response of a bulk dielectric to an intense few-cycle laser pulse is not solely determined by the pulse envelope, but also by ultrafast processes occurring during each optical cycle. Here, a method is presented for measuring the retardation of a probe pulse in a strong-field pumped, bulk dielectric with subcycle resolution in the pump-probe delay. Comparisons to model calculations show that the measurement is sensitive to the timing of the electronic Kerr response.