Wavefront analysis of subwavelength dielectric metalenses

We report the wavefront analysis in subwavelength dielectric metalenses. Experimentally, Shack-Hartmann wavefront sensor systems were employed to obtain lens aberrations and they were compared with theoretical calculations using Finite-difference Time-domain (FDTD) simulation. We were able to compute modal coefficients with Zernike functions implemented in Matlab. The measured and simulated wavefronts from metalenses were expressed as a sum of Zernike modes, typically 36 modes including the main 6 coefficients: defocus, vertical and obliques astigmatisms, vertical and horizontal comas, and spherical aberration. To assess the quality of the results, we reconstructed to wavefront data from the computed Zernike coefficients and compared to the originals as well. These results give us more confidence and accurate information about the effectiveness for practical use of metalenses.