Spherical Phase Metalenses: Intrinsic Suppression of Spherical Aberration via Equiphase Surface Modulation

TL;DR

This paper introduces a spherical phase profile for metalenses that intrinsically suppresses spherical aberration, enabling wide-aperture, diffraction-limited focusing with improved performance over traditional hyperbolic designs.

Contribution

The authors develop a spherical wavefront-based phase profile that prevents spherical aberration, providing a scalable framework for designing high-performance, wide-aperture metalenses.

Findings

Spherical phase reduces FWHM by 7.3% compared to hyperbolic designs.

Peak intensity increases by 20.4% with spherical phase.

Spherical phase maintains consistent focusing across different radii.

Abstract

Recent progress in large-scale metasurfaces requires phase profiles beyond traditional hyperbolic designs. We show hyperbolic phase distributions cause spherical aberration from mismatched light propagation geometry and unrealistic phase assumptions. By analyzing metalens fundamentals via isophase surfaces, we develop a spherical phase profile based on spherical wavefront theory. This method prevents spherical aberration, essential for wide-aperture metalenses. Simulations prove superior focusing: spherical phase reduces FWHM by 7.3% and increases peak intensity by 20.4% versus hyperbolic designs at 31.46 micron radius. Spherical phase maintains consistent focusing across radii, while hyperbolic phase shows strong correlation (R squared = 0.95) with aberration. We also propose a normal vector tracing metric to measure design aberrations. This work establishes a scalable framework for diffraction-limited metalenses.