Creating an Ultra-High Numerical Aperature Metalens at Visible Wavelengths

“Ansys Lumerical’s finite-difference time-domain (FDTD) simulation software was the ideal tool to reach our research goals into metalens design quickly and with confidence. It offers unprecedented accuracy, providing simulation results that closely match measured results and the performance needed for our optimization platform."

— Haowen Liang, Lead Investigator / Sun Yat-Sen University

Research Summary

The State Key Laboratory of Optoelectronic Materials & Technology at Sun Yat-sen University set out to develop a metalens with ultrahigh numerical aperture (NA) when front-immersed in oil, enabling subwavelength imaging with higher resolution. A novel hybrid optimization algorithm (HOA) finds optimal designs by iteratively simulating with the finite-difference time-domain (FDTD) method to determine transmission rate and absorption.

The goal of the research was to develop a better metalens with a higher NA and demonstrate that this could be achieved automatically via an optimization platform.

Results

After performing optimization using their HOA platform, the group at Sun Yat-Sen manufactured their design via patterning in a negative resist by electron beam lithography (EBL) and etched by inductively coupled plasma (ICP). The comparison between the measured and simulated results of the normalized intensity distribution of the focal spot in air. The optimization solution based on Ansys Lumerical FDTD resulted in a metalens design with measurements that closely match simulation results regarding focused spot size and efficiency.