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

Area of Science:

• Physics
• Materials Science
• Electrical Engineering

Background:

• Terahertz (THz) technology requires advanced optical components for integrated circuits.
• Plasmonic structures offer unique light-matter interactions in the THz spectrum.
• Developing components with tunable bandgaps and enhanced transmission is crucial.

Purpose of the Study:

• To experimentally and numerically demonstrate a composite plasmonic slab for THz applications.
• To investigate the resonant modes and transmission characteristics of the proposed structure.
• To explore the tunability of the plasmonic bandgap and Fano resonances.

Main Methods:

• Fabrication and characterization of a composite plasmonic slab with double-layer metallic gratings and a dielectric film.
• Numerical simulations using electric field vectors and charge distributions to analyze resonant modes.
• Experimental measurements of transverse magnetic (TM) wave transmission and Fano resonances.

Main Results:

• A composite plasmonic slab with a broad 40% bandgap in the THz region was achieved.
• Two resonant modes (symmetric plasmonic and hybrid plasmonic-dielectric) were identified.
• The dielectric film significantly enhanced TM wave transmission and induced Fano resonances.
• Tunable near-field coupling, bandgap, and Fano resonances were demonstrated by altering dielectric and grating parameters.

Conclusions:

• The composite plasmonic slab exhibits promising performance for THz applications.
• The structure's tunability makes it suitable for developing advanced THz integrated components.
• Potential applications include THz filters, polarizers, and sensors.