Extraordinary Magneto-Optical Effects and Transmission through Metal-Dielectric Plasmonic Systems

We predict theoretically a significant enhancement of the magneto-optical Faraday and Kerr effects in the bilayer systems of a metallic film perforated with subwavelength hole arrays and a uniform dielectric film magnetized perpendicular to its plane. Calculations, based on a rigorous coupled-wave analysis of Maxwell’s equations, demonstrate that in such structures the Faraday effect spectrum has several resonance peaks in the near-infrared range, some of them coinciding with transmittance peaks, providing simultaneous large Faraday rotation enhanced by an order of magnitude and high transmittance of about 35%.

Figure 1

Spectra of the optical transmittance [solid line in (a)], Faraday rotation [dashed line in (a) and solid line in (b)], and ellipticity [dashed line in (b)], Kerr rotation [solid line in (c)] and ellipticity [dashed line on (c)] of the bilayer system of perforated Au-film of thickness 68 nm and uniform Bi:YIG film of thickness 118 nm; $d=750\mathrm{nm}$, $r=395\mathrm{nm}$.

Figure 2

Faraday rotation (dashed line) and transmittance (solid line) versus the thickness $h$ of the magnetic layer. Geometrical parameters of the Au-BiYIG film are the same as in Fig. 1; $\lambda =963\mathrm{nm}$. Dotted line represents the Faraday rotation for the same single magnetic layer placed in optically matched surrounding medium.