From Dark to Bright: First-Order Perturbation Theory with Analytical Mode Normalization for Plasmonic Nanoantenna...

Area of Science:

• Photonics
• Plasmonics
• Optical metamaterials

Background:

• Photonic resonances in periodic structures are sensitive to the surrounding environment.
• Understanding and quantifying this sensitivity is crucial for developing novel optical sensors.
• Existing methods may not fully capture the behavior of different plasmonic modes under refractive index changes.

Purpose of the Study:

• To develop a first-order perturbation theory for calculating frequency shifts and linewidth changes of photonic resonances.
• To extend analytical mode normalization to periodic structures for accurate calculations.
• To apply the theory to quantify the sensitivity of dipolar and quadrupolar plasmonic modes.

Main Methods:

• Utilized a first-order perturbation theory based on resonant state expansion.
• Extended analytical mode normalization techniques for application to periodic structures.
• Calculated sensitivity by determining maximum frequency shift and optimal sensing volume for specific plasmonic modes.

Main Results:

• Successfully calculated frequency shifts and linewidth changes for photonic resonances in 1D and 2D periodic structures.
• Quantified the sensitivity of bright dipolar and darker quadrupolar plasmonic modes.
• Identified optimal sensing volumes for maximizing sensitivity.

Conclusions:

• The developed perturbation theory provides an accurate method for analyzing photonic resonance shifts in periodic structures.
• The theory enables quantitative assessment of plasmonic mode sensitivity for refractive index sensing.
• This work offers a framework for designing highly sensitive optical sensing devices.