Enhanced nonreciprocal effects in magnetoplasmonic systems supporting simultaneously localized and propagating plasmons.

R Kekesi,G Armelles,F García-Pérez,D Martín-Becerra,D Meneses-Rodríguez,A Cebollada

doi:10.1364/oe.23.008128

Abstract

Perforated magnetoplasmonic Au/Co/Au multilayers support both localized and propagating surface plasmon resonances. The presence of holes produces an enhancement of the magnetic field modulation of the propagating surface plasmon wavevector with respect to the isostructural continuous film in the spectral region corresponding to the hole associated localized plasmon resonance. This is due to the increased electromagnetic field in the surrounding area of the resonant hole, and the subsequent additional contribution to the magnetic modulation of the continuous film. This novel concept that gives rise to enhanced magnetic field induced nonreciprocal effects can be of interest in the development of innovative platforms for sensing applications, optical isolators and modulators.

Highlights

A system whose optical response is different for counter-propagating light–beams is called nonreciprocal [1]
We show extinction (1-T) spectra of both continuous and membrane layers. As it can be seen, the effect of incorporating holes into the continuous layer is twofold, with the logical increase of the transmittance and the appearance of a dip around 1.3 eV which is due to localized surface plasmons (LSP) associated to the holes [29]
We have shown that in magnetoplasmonic membranes, supporting MO active localized (LSP) and propagative Surface Plasmon (SP) (SPP) modes, an enhancement of magnetic field induced nonreciprocity effects occurs

Summary

Introduction

A system whose optical response is different for counter-propagating light–beams is called nonreciprocal [1]. It was found that the interaction between localized and propagating plasmon modes gave rise to a reduction of the SP magnetic modulation In this case, two aspects contributed in a negative way to the plasmon modulation: the elements that are responsible for the generation of the localized and propagating modes were spatially separated and one of them (the Au disks) was not MO active. Two aspects contributed in a negative way to the plasmon modulation: the elements that are responsible for the generation of the localized and propagating modes were spatially separated and one of them (the Au disks) was not MO active To circumvent these two drawbacks, in the present work we propose the use of a nanoperforated Au/Co/Au continuous film ( on, membrane). We will show how in the spectral region where the hole associated plasmon resonance is excited, and as a consequence of the hole resonance enhanced EM field, there is an additional contribution to the magnetic plasmon modulation with respect to the equivalent continuous film, opening novel routes for the development of nonreciprocal architectures based on modified continuous magnetoplasmonic films

Structure fabrication and characterization

Results and discussion

Conclusions