Three-dimensional analysis of subwavelength diffractive optical elements with the finite-difference time-domain...

Area of Science:

• Optics and Photonics
• Computational Electromagnetics
• Nanophotonics

Background:

• Subwavelength diffractive optical elements (DOEs) offer advanced light manipulation capabilities.
• Accurate simulation of these nanoscale devices is crucial for their design and application.
• Existing methods may not fully capture the complexities of 3D subwavelength structures.

Purpose of the Study:

• To develop and apply efficient three-dimensional (3D) finite-difference time-domain (FDTD) methods for analyzing subwavelength DOEs.
• To leverage the inherent properties of DOEs, such as symmetry, to enhance computational efficiency.
• To validate the developed 3D FDTD methods through experimental comparison.

Main Methods:

• Development of efficient 3D FDTD algorithms tailored for DOE analysis.
• Implementation of symmetry exploitation (e.g., axisymmetric methods) to reduce computational load.
• Experimental validation of an axisymmetric FDTD method against theoretical predictions or measurements.
• Application of the validated 3D FDTD method to various subwavelength structures.

Main Results:

• Demonstration of efficient and accurate 3D FDTD analysis for subwavelength DOEs.
• Successful validation of the general 3D FDTD method using an experimentally verified axisymmetric approach.
• Analysis of subwavelength gratings and lenses, including those lacking rotational symmetry.
• Characterization of a 2x2 subwavelength focusing array generator.

Conclusions:

• The developed 3D FDTD methods provide a powerful tool for the accurate simulation of subwavelength DOEs.
• Exploiting symmetry significantly enhances the efficiency of FDTD simulations for relevant DOE geometries.
• The validated methods are applicable to a wide range of subwavelength optical components, facilitating their design and optimization.