Topology-optimized metasurfaces: impact of initial geometric layout

Area of Science:

• Metasurface Engineering
• Nanophotonics
• Computational Design

Background:

• Topology optimization is an inverse design method for creating high-performance metasurface devices.
• Selecting appropriate initial geometries is essential for successful optimization within a local design phase space.

Purpose of the Study:

• To investigate the influence of initial geometric layouts on the performance of topology-optimized large-angle metagrating deflectors.
• To determine if conventional metasurface designs are suitable initial layouts for achieving ultra-high efficiency.

Main Methods:

• Utilized topology optimization for designing metagrating deflectors.
• Compared device performance using conventional dielectric nanopost initial layouts versus random initial layouts.
• Conducted numerical experiments to evaluate device efficiencies.

Main Results:

• Metagrating deflectors with conventional initial layouts achieved efficiencies around 65%.
• Metagrating deflectors with random initial layouts reached ultra-high efficiencies up to 94%.
• Conventional metasurface designs as initial layouts may limit the achievable efficiency for large-angle devices.

Conclusions:

• The choice of initial geometric layout critically impacts the performance of topology-optimized metasurfaces.
• Non-trivial and random initial topologies are required for achieving ultra-high efficiencies in large-angle metagrating deflectors.
• Future metasurface designs should explore diverse and complex initial geometries for enhanced performance.