Silicon-based asymmetric dimer-resonator grating for narrowband perfect absorption and sensing

Area of Science:

• Photonics and Nanotechnology
• Optical Metamaterials
• Infrared Spectroscopy

Background:

• Developing efficient narrowband absorbers is crucial for optical sensing and spectral filtering.
• Silicon-based nanostructures offer tunable optical properties for advanced photonic devices.
• Existing absorbers often lack the required sharpness and sensitivity for precise measurements.

Purpose of the Study:

• To design and demonstrate an ultra-narrowband absorber platform based on asymmetric silicon dimer-resonators.
• To achieve high absorptivity (>99%) within the 3000–4000 nm infrared range.
• To evaluate the platform's performance for optical sensing applications, focusing on sensitivity and figure of merit (FOM).

Main Methods:

• Utilizing asymmetric silicon-based dimer-resonators in a grating configuration.
• Investigating strong scattering coupling and magnetic resonances for enhanced absorption.
• Analyzing the effects of polarization and incident angles on absorption characteristics.

Main Results:

• Achieved two ultra-narrowband absorption peaks with >99% absorptivity at 3468 nm and 3562 nm.
• Demonstrated high sensitivity factors for optical sensing: S = 3193 nm/RIU (FOM = 532) and S = 3120 nm/RIU (FOM = 390).
• Confirmed tunability of absorption intensity and wavelengths via polarization and incident angles.

Conclusions:

• The proposed silicon-based resonant scheme enables ultra-sharp perfect absorption.
• The platform exhibits high performance in optical sensing, suitable for refractive index detection.
• Potential applications include biosensing, spectral filtering, and other fields requiring precise optical manipulation.