Coenhancement of optical transmission and Faraday effect with magnetic plasmonic nanopillars

Abstract Coenhancement of optical transmission and the Faraday effect are always the goals to pursue for photoelectric devices, while the current research almost concentrated on the properties based on gratings and photonic crystal structures. Nanopillars (NPs) are structures with a relatively simple preparation that have been widely used in many fields, where the Faraday effect has been rarely studied. In this work, a Faraday rotator in the wavelength range of 500–800 nm is proposed based on bismuth–iron garnet (BIG) with magnetic plasmonic NPs structure, in which the hemispherical shaped silver covered on top and silica used as the substrate for enhancement effect. Through this rotator, two peak values for both Faraday rotation angle and transmittance can be achieved, no matter what the wavelength changes are. The transmittance, Faraday rotation angle, and figure of merit (FOM) can be controlled by tuning the thickness and lattice constant of the BIG NPs, the radius of the silver hemisphere, and the external magnetic field. Furthermore, the physics mechanism of the large Faraday effect and extraordinary optical transmission is explained by employing the electric field distribution diagrams. Finally, the optimized FOM simply can be raised to 0.9, achieving well overall performance in the visible light range. The results have certain values for achieving simpler and better performance of magneto-optical devices under visible wavelength range, such as optical isolators and magneto-optical sensors.