Metasurfaces provide a new basis for recasting optical components into thin planar elements, easy to optically align and control aberrations, leading to a major reduction in footprint, system complexity and cost as well as the introduction of new optical functions.1, 2, 3. Their planarity allows for fabrication routes directly in line with conventional processes of the mature integrated circuit (IC) industry.1 I foresee great technological and scientific penetration of CMOS compatible metasurface-based optical components, ranging from metalenses4-6 to novel polarization optics7, 8. Camera modules for high volume applications, such as cell phones, will be the greatest beneficiaries. The technology required to mass produce metasurfaces dates back to the early 1990s, when the feature sizes of semiconductor manufacturing became smaller than the wavelength of light, advancing in stride with Moore’s law. This provides the possibility of unifying two industries: semiconductor manufacturing and lens-making, whereby the same technology used to make computer chips is used to make metalenses and other optical components, based on metasurfaces. A major obstacle for this to happen had to be overcome. With metasurfaces, the data describing large designs are faced with the challenge of enormous file sizes due to having millions or billions of individual microscopic metaelements (necessitated by the subwavelength size criterion) described over macroscopically large device areas. This extremely high data density over large areas generates unmanageably large total file sizes, limiting the fabrication of optical components such as metalenses to sizes no larger than a few millimeters. Using our new scalable metasurface layout compression algorithm (METAC) that exponentially reduces design file sizes (by 3 orders of magnitude for a centimeter diameter lens) and stepper photolithography, we have recently shown the design and fabrication of metalenses with extremely large areas, up to centimeters in diameter and beyond.9 Finally I envision a future of digital optics based on metasurfaces with increased density of optical components and functionalities per metasurface; it is tempting to speculate that an empirical law might govern its growth, akin to Moore’s Law for digital electronics.
References: 1. F. Capasso, Nanophotonics DOI: 10.1515/nanoph-2018-0004 (2018) 2. N. Yu et al. Science 334, 333 (2011) 3. N. Yu and F. Capasso Nature Materials 13, 139 (2014) 4. M. Khorasaninejad et al. Science 352, 1190 (2016) 5. M. Khorasaninejad and F. Capasso, Science 358, 8100 (2017) 6. W-T. Chen et al. Nature Nanotechnology (2018) doi:10.1038/s41565-017-0034-6 7. J. P. B. Mueller et al. Physical Review Letters 118, 113901 (2017) 8. J. P. B. Mueller et al. Optica 3, 42 (2016) 9. A. She et al. Optics Express 26, 1573 (2018)