Surface-plasmon-polariton-driven narrow-linewidth magneto-optics in Ni nanodisk arrays

• Published in: Nanophotonics (Berlin, Germany) Vol. 9; no. 1; pp. 113 - 121
• Main Authors: Freire-Fernández, Francisco, Kataja, Mikko, van Dijken, Sebastiaan
• Format: Journal Article
• Language: English
• Published: Berlin De Gruyter 01.01.2020; Walter de Gruyter GmbH
• Subjects: Arrays; Bilayers; Free electrons; Kerr effects; Kerr magnetooptical effect; Lattice parameters; magneto-optical Kerr effect; Magneto-optics; magnetoplasmonics; nanoparticle array; Optical communication; Optics; Polaritons; Reference systems; Resonance; Silicon dioxide; surface lattice resonance; surface plasmon polariton; Thickness
• ISSN: 2192-8606; 2192-8614
• DOI: 10.1515/nanoph-2019-0331

The field of magnetoplasmonics exploits interactions between light and magnetic matter at the nanoscale for light manipulation and resonant magneto-optics. One of the great challenges of this field is overcoming optical losses in magnetic metals. Here, we exploit surface plasmon polaritons (SPPs) excited at the interface of an SiO /Au bilayer to induce strong magneto-optical responses on the Ni nanodisks of a periodic array. Using a reference system made of Au nanodisks, we show that optical losses in Ni hardly broaden the linewidth of SPP-driven magneto-optical signals. Loss mitigation is attained because the free electrons in the Ni nanodisks are driven into forced oscillations away from their plasmon resonance. By varying the SiO layer thickness and lattice constant of the Ni nanodisk array, we demonstrate tailoring of intense magneto-optical Kerr effects with a spectral linewidth down to ~25 nm. Our results provide important hints on how to circumvent optical losses and enhance magneto-optical signals via the design of off-resonance magnetoplasmonic driving mechanisms.