Lightfast optical current in dielectric by Plasmonically induced local field

摘要

Recently, ultrafast strong field induced optical current in SiO_2 dielectric medium has demonstrated. By foaming laser intensity more than 10~(13) W·cm~(-2) in the dielectric material, the optical current was generated in a dielectric gap without any DC bias. This phenomenon is affected by the strength electric field of incident laser field and the generated electrons follow the speed of optical frequency enabling lightfast electronics in the future. In this study, we especially adopted nanoplasmonic field to trigger and control current flow in a nanometer spatial resolution. Nanoplasmonic field enables to manipulate light field in nanoscale domain. By using nanoplasmonic field, optically induced current flow can be selectively controlled by characteristic of nanoplasmonic nanostructure. For the first demonstration, saw tooth like 2-D nano Au pattern was numerically and experimentally investigated to boost up the laser intensity of incident 4.5 fs laser pulse with minimum field distortion and broadening. The intensity enhancement factor of plasmonic field at the saw tooth tip was ～40, enabling Wannier-Stark effect with incidence intensity level of only 10~(11)W·cm~(-2) in the TiO_2 substrate. The carrier envelope phase of laser pulse is controlled to measure ultrafast optical current generation in dielectric medium by plasmonically induced strong near-field. This will be the basis for developing practical lightfast optical electronics in the future.