Systematic Performance Analysis of a Propagation‐Type Metalens Under Practical Fabrication Imperfections

Metalenses based on dielectric metasurfaces have emerged as a powerful platform for realizing compact and multifunctional optical systems. However, the optical performance of practical devices is influenced by fabrication imperfections inherent to nanomanufacturing processes, which cause deviations from ideal design parameters. In this work, we establish a quantitative framework that connects fabrication‐induced geometric errors to system‐level focusing performance through a statistical phase‐error model. Using TiO 2 nanopillars on an indium tin oxide substrate as a representative unit cell, three dominant fabrication imperfections—uniform size deviation, sidewall inclination, and corner rounding—are analyzed via full‐wave simulations at 532 nm. Phase deviations were modeled by Gaussian functions to describe their statistical behavior. Random phase disturbances generated from the combined distribution were applied to the metalens. Simulations indicate that typical fabrication errors cause only minor efficiency loss, while the focal position and spot shape remain almost unchanged. Furthermore, this study provides a generalizable statistical approach for predicting and optimizing metasurface performance under realistic manufacturing conditions.