Abstract-Terahertz composite plasmonic slabs based on double-layer metallic gratings

Dejun Liu, Lin Chen, Xiaohu Wu, and Feng Liu

Sketch of the composite plasmonic slab (CPS). The slab consists of double-layer metal gratings and a dielectric film. (a) The side view of the CPS. (b) The 3D model of the CPS. (c) The image of the experimental sample of a single-layer metal (copper) grating.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-28-12-18212

One composite plasmonic slab with a broad bandgap (40%) is experimentally and numerically demonstrated in the terahertz (THz) region. The composite slab consists of double-layer metallic gratings and a dielectric film, which supports two resonant modes. Electric field vectors and charge distributions proved that the low-frequency resonant mode originates from the symmetric plasmonic mode, while the high-frequency resonant mode is induced by the hybrid mode of plasmonic and dielectric modes. Compared with the double-layer metallic grating, the inserted dielectric film significantly enhances the transmission of the transverse magnetic (TM) waves and induces Fano resonances. The near-field coupling between metal gratings and dielectric film can be manipulated by changing the thickness and the refractive index of dielectric films. We further demonstrated that the plasmonic bandgap can be manipulated by tuning the grating width. These results suggest that this composite plasmonic slab is promising in terahertz integrated components development such as a filter, polarizer, or sensor.

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Terahertz composite plasmonic slabs based on double-layer metallic gratings

Dejun Liu, Lin Chen, Feng Liu

https://arxiv.org/abs/2003.04113

A composite plasmonic slab based on double-layer metallic gratings and a dielectric film is experimentally and numerically demonstrated in terahertz (THz) regions, which can support two resonance modes and then form a broad bandgap (40%). As compared to the double-layer metal grating, the dielectric film in composite THz slabs significantly enhances the transmission of the transverse magnetic (TM) mode. Electric field vector proved that the low-frequency resonance mode originates from the symmetric plasmonic mode and the high-frequency resonance mode is induced by the hybrid mode of plasmonic and dielectric modes. The inherently near field coupling between metal gratings and dielectric film has been analyzed by changing the structural parameters. We further demonstrate that by tuning the metallic grating width, the plasmonic bandgap can be manipulated. These results suggest that this composite plasmonic slab has great potential for use as a filter, polarizer, and sensor in THz regions.