Near-Infrared Perfect Absorption and Refractive Index Sensing Enabled by Split Ring Nanostructures.

Area of Science:

• Nanotechnology
• Plasmonics
• Optical Metamaterials

Background:

• Plasmonic nanostructures are crucial for narrowband perfect absorbers.
• Applications include biosensing and environmental detection.
• Metal-insulator-metal (MIM) multilayers offer tunable optical properties.

Purpose of the Study:

• Investigate arrayed split ring nanostructures in MIM multilayers.
• Achieve high light absorption in the near-infrared (NIR) spectral range.
• Evaluate sensing capabilities for biosensing and environmental detection.

Main Methods:

• Fabrication of arrayed split ring nanostructures in MIM multilayers.
• Characterization of optical absorption spectra.
• Analysis of electric and magnetic field resonances.
• Tuning of resonant peak via structural parameters (dielectric thickness, period, split ring geometry).
• Sensitivity measurements using bio-analytes with varying refractive indices.

Main Results:

• Maximum light absorption of 99.94% achieved in the NIR spectral range.
• High absorption attributed to Fabry-Pérot cavity resonance and strong field confinement.
• Resonant peak tunability demonstrated by structural parameter engineering.
• High sensing sensitivity achieved: 326 nm/RIU (visible) and 504 nm/RIU (NIR).

Conclusions:

• The designed MIM nanostructure functions as an efficient narrowband perfect absorber.
• The nanostructure exhibits excellent tunability for specific wavelength targeting.
• Demonstrated high sensitivity makes it a promising candidate for advanced biosensors and environmental detection systems.