Robust numerical evaluation of circular dichroism from chiral medium/nanostructure coupled systems using the...

Area of Science:

• Plasmonics
• Computational electromagnetics
• Chiroptics

Background:

• Circular dichroism (CD) signals from chiral molecules are enhanced by plasmonic nanostructures.
• Finite element method (FEM) is widely used for simulating CD enhancement.
• Existing FEM calculations suffer from numerical artifacts due to improper space discretization, hindering accurate CD simulations.

Purpose of the Study:

• To introduce a new meshing rule for FEM to improve numerical accuracy in CD simulations.
• To suppress unwanted numerical artifacts in CD calculations.
• To enable reliable enhancement of CD signals from chiral molecules using plasmonic nanostructures.

Main Methods:

• Developed a novel meshing rule for FEM simulations.
• Implemented a mirror-symmetric mesh configuration.
• Applied the meshing scheme to a nanostructure/chiral molecule coupled system.

Main Results:

• The new meshing rule significantly improves the numerical accuracy of CD simulations.
• Mirror-symmetric meshing suppresses numerical artifacts by canceling them out in opposite circularly polarized waves.
• Demonstrated significant CD signal enhancement in a coupled nanostructure/chiral molecule system.

Conclusions:

• The developed meshing scheme effectively addresses numerical artifacts in FEM-based CD simulations.
• This method allows for accurate discrimination between small CD signals and numerical errors.
• The approach is directly applicable to simulations of natural chiral molecules with weak chiroptical responses.