Light-Field-Controlled PHz Currents in Metals

Abstract Oriented electric currents in metals are routinely driven by applying an external electric potential. Although the response of electrons to the external electric fields occurs within attoseconds, conventional electronics do not utilize this speed potential. Ultrafast laser technology, which delivers laser pulses with controlled shapes of electric fields that switch direction at PHz frequencies, opens new perspectives for driving electric currents in metals. Here, we demonstrate an interaction of light with nm-thick metallic layers, that leads to a generation of PHz-bandwidth electric currents, providing evidence that currents in metals can be optically controlled. We show that the implantation of metallic layers into a dielectric matrix leads up to 40 times increase of the sensitivity in contrast to bare dielectric, decreasing the intensity threshold for the lightwave electronics. We establish a link between electronic and optical properties by identifying an empirical relationship between the index of nonlinear susceptibility X(3) and the generated current. We provide an intraband-motion model elucidating the origin of the measured current.