Spatiotemporal manipulation of localized plasmon modes within nano-femto scale using femtosecond chirped pulses

Arbitrarily control of electromagnetic field in femto-nano spatiotemporal scale can be realized by illuminating metallic nanoparticle with well-defined femtosecond laser pulse, which is at heart of current ambitious research endeavors in nanophotonics. However, the quantitative relation of the behavior of localized field with the incident laser pulse hasn’t yet been revealed. Here, active switching of localized near field is achieved by single chirped laser pulse in asymmetric Au nanocross system within the pulse duration using Finite Differential Time Domain algorithm. Temporal interval of energy switching between the two poles of nanocross is determined by the chirp of the laser pulse According to the temporal evolution, we found that field enhancement is asymmetric for positively and negatively chirped pulses as the consequence of the imbalance response of the plasmonic field around resonant frequency. It is demonstrated that under the excitation pulse of specific spectrum, field enhancement can also be effectively modulated by chirped laser pulse, providing a new degree of freedom for manipulating the dynamics of localized surface plasmons in nanoparticle.