Design of broadband near-infrared metalens with polarization-insensitive arbitrarily controlled dispersion

Metalenses are compact, lightweight, and can effectively modulate the optical field at the subwavelength scale. The favorable properties help reduce the size and complexity of optical systems, and therefore, these devices may partially replace traditional optical elements. The major challenge in the practical use of metalenses is the chromatic dispersion. Herein, a square prism was used as the unit structure, and the phase and chromatic dispersions were considered simultaneously. The particle swarm optimization algorithm was used to find an appropriate phase compensation. The dispersion freely controlled across the broad spectral range of 1300–2100 nm was realized in the polarization-insensitive mode. In achromatic mode, the average focusing efficiency in this band was 45.55 % (56.85 % without considering transmittance), and the maximum focusing efficiency was 57.94 % (67.47 % without considering transmittance). Moreover, this study employed the point spread function of the metalens for simulated imaging to validate the imaging performance. The metalens can achieve achromatic imaging within a 36° field of view with a maximum image resolution of up to 641 lp/mm. These properties enable broad application prospects for metalenses to achieve broadband and miniaturization within the near-infrared band.