Dammann metasurface route to overcoming the uniformity defects in two-dimensional beam multipliers.

Dammann gratings-beam-shaping optical elements acting as beam multipliers with equal-power beams-are a key element in three-dimensional imaging based on structured light and beam combiners for high-power laser applications. However, two-dimensional Dammann grating structures suffer from a significant reduction in the uniformity among the diffraction orders. Here, we report Dammann metasurfaces based on the geometric phase as the structure realization for the target phase profile, which outperform the capabilities of Dammann gratings by overcoming the uniformity defects in their two-dimensional diffraction patterns. We showed that two-dimensional Dammann metasurfaces exhibit high uniformity and diffraction efficiency, in contrast to Dammann gratings, by overcoming the uniformity defects via a robust and highly precise phase imprint. Moreover, Dammann metasurfaces outperform their grating counterparts by exhibiting a polarization-independent response and a broadband operation. This study reveals that by providing physics-driven solutions, metasurfaces can outperform the capabilities of their bulk optics counterparts while facilitating virtually flat, ultrathin, and lightweight optics.