Calculating phase profiles of advanced metasurface-based optical systems

What is it about?

This study introduces a simple yet powerful geometric approach—the string method—for designing optical systems based on metasurfaces, such as metalenses and light concentrators. Traditionally, calculating the phase profiles that control how metasurfaces manipulate light requires solving complex equations. The string method provides an intuitive shortcut: it represents light paths as “strings” of equal optical length and uses this geometric analogy to determine the ideal phase profile for each metasurface. Using this approach, the research demonstrates how to design both imaging and non-imaging systems, including single and double metalenses, as well as metasurface concentrators that collect or focus light efficiently. The method can also be extended to systems with multiple metasurfaces, enabling the development of compact, high-performance optical devices—from smartphone cameras and microscopes to solar concentrators and optical sensors.

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Photo by Galactic Nikita on Unsplash

Photo by Galactic Nikita on Unsplash

Why is it important?

The string method simplifies one of the most challenging steps in metasurface optics: obtaining the phase profile that dictates how light is bent, focused, or distributed. By offering a mathematically simple yet physically accurate solution, it makes metasurface design faster, more intuitive, and accessible to a wider range of researchers and engineers. This geometric method is not only a practical tool but also a conceptual bridge between classical optics and the emerging field of metaoptics. It can serve as the first step for optimizing complex systems—correcting aberrations, minimizing chromatic effects, and designing multi-element metasurface assemblies. Ultimately, it provides a universal framework for designing the next generation of compact, integrated optical systems.

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