Micro-dimensional oscillation-based optimization for a dielectric metalens in the mid-infrared

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Metasurfaces and miniaturized optical devices have seen significant advancements.
• Metalenses, a key application of metasurfaces, are under extensive research for improved focusing capabilities.

Purpose of the Study:

• To enhance the focusing performance of initial Pancharatnam-Berry (PB) phase metalenses.
• To optimize nanopillar geometric parameters using a novel micro-dimensional oscillation concept.

Main Methods:

• A grouping iteration strategy was employed to divide the large-scale optimization space into overlapping groups.
• An improved genetic-simulated annealing (IGSA) algorithm, featuring adaptive probabilities, was used for optimizing each group.
• Micro-dimensional oscillation was introduced to refine nanopillar geometry.

Main Results:

• The maximum field intensity of the central hot spot increased by approximately 8% compared to the initial metalens.
• Side lobe intensity remained nearly constant, while the central hot spot was amplified.
• The optimization strategy reduced loss rate and computational effort.

Conclusions:

• The proposed optimization method significantly improves metalens focusing performance.
• The enhanced central hot spot and stable side lobes offer potential for high imaging contrast applications.
• This research contributes to the development of advanced integrated and miniaturized optical devices.