Broadband Faraday Rotation Enhancement in Magneto-Plasmonic Quasi-Crystalline Structure

Magneto-plasmonic nanostructures integrating plasmonics and magneto-optics offer a unique method to control light through magnetic fields. The Faraday effect in magneto-optical materials leads to the rotation of the polarization plane of light, which is particularly advantageous for optical isolators and plays a critical role in optical systems. However, available magneto-optical materials exhibit a weak Faraday effect in the visible to near-infrared frequency range, resulting in bulky Faraday isolators. Here, we report a broadband enhancement in the Faraday rotation in a Plasmonic quasi-crystalline (PIQC) structure comprising a patterned gold layer on top of the ferromagnetic thin films. The enhancement primarily results from the excitation of surface plasmon polaritons (SPP) that propagate at the interface between gold and garnet in the PIQC structure.