Terahertz faraday rotation of iron film enhanced by slot antennas

Abstract

The magneto-optic effects are enhanced in structures with periodicity and ferromagnetic materials. The magneto-optic effect refers to changes in the optical characteristics of a substance when influenced by an external magnetic field. The Faraday effect, one of the magneto-optical effects, refers to the shift in the polarization axis of linear polarization wave due to an external magnetic field applied to a material. Based on these attempts, this thesis explores the terahertz transmission characteristics and magneto- optical effects by varying the gap size of slot antennas. Slot antennas, rectangular structures with a gap width on a metallic film, are known to show strong resonance at certain frequency and sensitivity to the dielectric environment in transmission properties. Slot antennas were fabricated using photolithography and electron beam lithography. The slot antennas exhibited decreased transmission when exposed to a magnetic field and observed maximum Faraday rotation near the resonance frequency were noted. The tendency of this phenomenon becomes larger with smaller antenna's gap. With well-controlled quality of the ferromagnetic material and antenna structure, this scheme is expected to demonstrate substantial Faraday rotation within a specific frequency range.