THz study of field screening: 10 fs-100 fs regime

Here, we present the first THz study of field screening on such a time scale by using a 10 fs laser, and a correlation technique. We prove for the first time that both the polarisation and the acceleration ofthe electron-hole pairs by the dc electric field contribute to THz emission. We show that the polarization contribution has a speed comparable to the optical pulse duration, while the transport contribution at early times is determined by the ballistic acceleration of the electron hole pairs