Metasurfaces are nanostructured thin films designed to manipulate the phase, amplitude and polarization of light. Metalenses, a type of metasurface that focuses light like a lens, can focus all wavelengths to specific locations.
By customizing the geometric design of a metasurface’s nanostructures, Sisler et al. designed a metalens that could exhibit multiple functions at once. In doing so, they were not only able to focus different colors to different spots but could also fine tune that focus, opening the possibility for applications in spectroscopy or microscopy techniques.
“By showing that we can achieve very unique functionalities based on dispersion engineering, we can improve and increase the applications of metalenses in different fields,” said author Jared Sisler.
Using their dispersion engineering method, the authors were able to achieve customized focal length shifts at blue and red wavelengths. The method gives the user control over whether the focal length shift exhibits achromatic, refractive or diffractive behavior.
“The ability to design, at will, how a lens responds to different wavelengths, something impossible with existing lens technologies, will have a major impact in science and applications” said author Federico Capasso.
A major benefit of these metalenses is that they are mass producible.
“Fast manufacturing of metalenses is the most important next step,” said author Wei Ting Chen. “This can be realized with deep ultraviolet lithography or roll-to-roll nanoimprint.”
Source: “Controlling dispersion in multifunctional metasurfaces,” by Jared Sisler, Wei Ting Chen, Alexander Y. Zhu, and Federico Capasso, APL Photonics (2020). The article can be accessed at https://doi.org/10.1063/1.5142637.