Adaptive Perfectly Matched Layer for Wood's anomalies in diffraction gratings.

Area of Science:

• Electromagnetics and Optics
• Computational Physics

Background:

• Diffraction grating modeling is crucial for optical device design.
• Wood's anomalies, occurring near grazing angles, pose challenges for numerical simulations.
• Classical Perfectly Matched Layers (PML) have limitations in absorbing these specific diffracted orders.

Purpose of the Study:

• To develop and validate an Adaptive Perfectly Matched Layer (APML) for enhanced diffraction grating modeling.
• To address the challenge of efficiently absorbing diffracted orders near grazing angles (Wood's anomalies).
• To compare the performance of APML against classical PML in numerical simulations.

Main Methods:

• Implementation of an Adaptive Perfectly Matched Layer (APML) using coordinate stretching tailored to incident fields and grating parameters.
• Utilizing a finite element method (FEM) scheme for numerical implementation.
• Applying the APML to model a dielectric slit grating and comparing results with classical PML.

Main Results:

• The APML demonstrates efficient absorption of diffracted orders, particularly near grazing angles where Wood's anomalies occur.
• Numerical simulations show superior performance of APML compared to classical PML with constant stretching.
• The adaptive nature of APML allows for better handling of complex electromagnetic phenomena in gratings.

Conclusions:

• The proposed APML is an effective advancement for diffraction grating modeling, especially for phenomena like Wood's anomalies.
• APML offers a more robust and accurate solution than traditional PML for specific challenging cases.
• This method enhances the capability of finite element method (FEM) simulations in computational electromagnetics.