Nonlinear magneto-optical transversal Kerr effect in magneto-plasmonic nanosandwiches

Abstract

Optical properties of a planar array of composite Au/Co/Au magnetic plasmonic nanosandwiches of 60 and 110 nm in diameter are studied using linear absorption and optical second harmonic generation (SHG) technique. Linear absorption spectrum reveals a peak centered at about 2.1 eV, which is associated with the excitation of localized surface plasmon in Au/Co/Au nanosandwiches. The nonlinear-optical experiments are performed using the fundamental radiation of YAG: Nd3+ laser at 1064 nm, so that the SHG radiation corresponds to the resonant plasmon line. It is shown that in spite of spatial inhomogeneity of such an ensemble, the SHG response in the nanosandwiches of the diameter 110 nm is presumably polarized and specular, i.e. substantially coherent. At the same time, for nanosandwiches with the diameter of 60 nm the SHG signal is observed in the form of the hyper-Rayleigh scattering. Plasmon-assisted effects in nonlinear-optical response of nanosandwiches reveal themselves by different relative amplitude and phase of odd in magnetization component of the SHG field as compared with those in plasmon-free continuous trilayer structure.