Carrier transport after ultrashort-pulse laser excitation in dielectric materials leads to 10MVm−1 electric fields: Transient birefringence and emission of terahertz radiation

Charge-carrier transport is investigated theoretically in a high-band-gap dielectric material excited by intense ultrashort laser pulses. Simulations of fused silica reveal that the photo-Dember effect causes a 107Vm-1 electric field to build up inside the material. It is shown that this electric field can induce a significant transient optical anisotropy in the dielectric, which may help reconcile earlier reports of an ultrafast onset of birefringence in highly excited fused silica. The time-dependent electric field will also lead to emission of a broadband THz pulse propagating out from and along the dielectric surface.