Interparticle-Coupled Metasurface for Infrared Plasmonic Absorption

Abstract

Plasmonic metasurfaces operating in the long-wavelength infrared region (LWIR) are primarily employed for bio-sensing and imaging applications. The key factor affecting the capability of LWIR metasurfaces is absorption efficiency, whereas significant advances have been made to attain higher absorption intensities, using metal-insulator-metal (MIM) stack structures, which require a complex nanofabrication process and repetition of the patterning process to develop each layer. This study experimentally demonstrates the integration of metasurfaces with plasmonic resonators. The metasurfaces and plasmonic resonators are developed through electron beam lithography (EBL) on the same plane of the Silicon substrate. The fabricated prototype has broad incident angle stability at a bandwidth of $2\mu \text{m}$ with near-perfect absorption at $8\mu \text{m}$ resonance wavelength when characterized through the Attenuated Total Reflectance - Fourier Transforms Infrared Spectroscopy (ATR-FTIR) setup. The metasurface device achieves tunable resonance behavior when the incident angles reach up to 70°. The proposed integration of metasurface with plasmonic resonators are well-suited for enhanced biosensing applications with metasurface devices.

Keywords

• Absorption
• electron beam lithography
• metasurface
• optical characterization
• plasmonic coupling