Metasurface lenses promise to replace bulk optical components with thin layers of structured media, that can be mass-produced, and integrated with other photonic and electronic components. Unfortunately, their thin size typically limits their operating bandwidth, leading to unfavourable trade-offs between aperture size, focal length, efficiency and bandwidth. An alternative approach is to create a metasurface where the performance is carefully matched at several discrete wavelengths. This approach is suitable for applications for which the incident wavelengths are known in advance. However, when white light is incident upon such a system, significant chromatic aberration will result. In an article recently published in Photonics Research
, Li et al. from Nanjing University overcome this issue by integrating a multi-wavelength metasurface lens with a matched bandpass filter. By rejecting all wavelengths outside of the carefully optimized red, green and blue bands, the authors greatly suppress chromatic aberrations, and demonstrate imaging with their lens under white light illumination from a halogen source.
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