In recent years, metasurfaces have attracted significant attention due to their ability to control many degrees of freedom of an incoming beam, including phase, amplitude, polarization, and dispersion. Many device demonstrations followed, opening opportunities in a wide range of applications such as imaging, polarization optics, sensing, augmented and virtual reality systems, and telecommunications. Despite such broad interest, transitioning from proof-of-principle demonstrations to high-efficiency, practical devices has been extraordinarily challenging in many areas, especially those involving complex functions such as polarization insensitivity, dealing with complex input and output wavefronts in high-numerical-aperture systems, manipulating multiple wavelengths, etc.
This challenge is rooted in the fundamental physics governing the interaction of light and structured surfaces. It has become clear that engineering complex nonlocal coupling between neighboring meta-atoms is key to achieving high efficiencies. A succession of inverse-designed metasurfaces based on topology optimization has opened a route to deal with the physics but unfortunately, this approach leads to complex, difficult to manufacture structures.
The collaboration between Corning and Harvard proposes an alternative inverse design method that simultaneously deals with nonlocal behavior and rigorously controls the complexity of the structure. While maintaining the generality of the input-output field manipulations, this method allows only smooth boundary deformations of meta-atoms, avoiding appearances of sharp features, holes, small gaps or small features, ensuring compatibility with the fabrication process. The paper includes the theoretical formulation and various numerical and experimental demonstrations of meta-gratings and meta-lenses. The results provide a path towards practical and high-efficiency metasurfaces, representing a step forward in making practical devices for a broader range of applications.
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References
DOI
Original Source URL
https://doi.org/10.1038/s41377-024-01629-5
Funding information
This work was supported by Corning.
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