Enhanced Faraday effect by magneto-plasmonic structure design composed of bismuth-iron garnet

In this work, a magneto-plasmonic structure Faraday rotator based on bismuth-iron garnet with opened metal microstructure is proposed, through changing the opening angle, aperture size, and thickness of the bismuth-iron garnet, and the performance of Faraday rotation and transmittance are investigated in the mid-infrared wavelength band. The optimal performance of the double-opened toroidal magneto-plasmonic structure was obtained, in which a wider spectral range and a larger Faraday rotation angle can be achieved compared to the bare film and the unopened Faraday rotator. The maximum enhancement factor of big Faraday rotation and larger figure of merit are also obtained. And in making changes to the bismuth iron garnet thickness, more stable data can be obtained in the spectral range. In addition, the electric field diagrams at the intersection of different materials are presented, and the physical mechanism of the Faraday rotation effect is explained. Compared to periodic arrays of plasmas, the structures designed in this paper can produce greater extraordinary optical transmission effects, offering promising prospects for some magneto-optical device applications such as optoisolators.