Accurate characterization of complex Bloch modes in optical chain waveguides using real-valued computations

Area of Science:

• Photonics and Nanophotonics
• Computational Electromagnetics
• Materials Science

Background:

• Optical chain waveguides with complex geometries and materials pose challenges for Bloch mode analysis.
• Existing methods often require iterative complex root estimation, limiting accuracy and efficiency.

Purpose of the Study:

• To develop a highly accurate and easy-to-implement method for characterizing complex Bloch modes in 3D optical waveguides.
• To address limitations in computational resources for analyzing complex geometries.

Main Methods:

• Combines commercial electromagnetic (EM) solver results with analytical post-processing.
• Utilizes real-valued computations to determine the complex Bloch wavevector.
• Introduces a single unit-cell technique for efficient meshing of 3D geometries.

Main Results:

• Achieves superior accuracy in Bloch wavevector calculation, even with radiation and material losses.
• Demonstrates excellent agreement with existing numerical and experimental data in plasmonic and dielectric case studies.
• The single unit-cell technique allows for dense meshing within limited computational resources.

Conclusions:

• The proposed method offers a robust, general, and accurate approach for Bloch mode characterization.
• It is highly beneficial for the study of various waveguide-based nanophotonic components.
• Simplifies analysis of complex 3D layered structures with dispersive negative-epsilon materials.