The ability to control the behaviour of light using nanometric devices has opened the door to a whole new field of research and innovative applications. Photonics has become a key technology for a wide variety of fields. The study and development of metamaterials – artificial materials composed of elementary building blocks arranged at sub-wavelength distances – represented a major step forward in the field of nanotechnology. These structures make it possible to precisely control the interaction between light and matter, offering properties that cannot be obtained with conventional materials.
In this category, metasurfaces have been the most extensively studied. By carefully crafting these artificial surfaces, it is possible to obtain arbitrarily change the phase, amplitude, polarization, and direction of a wave front, implementing the same functionalities of traditional optical components but using ultra-thin structures that can potentially be very easily integrated into a multitude of systems. Even more interestingly, with these nanostructured surfaces, it is also possible to obtain behaviours that are impossible or very difficult to achieve with traditional optical elements, such as aberration-free lenses.
Y. Liu, Y. Liu, J. Zhang, X. L. Roux, E. Cassan, D. Marris-Morini, L. Vivien, C. Alonso-Ramos, and D. Melati, ‘Broadband behavior of quadratic metalenses with a wide field of view’, Opt. Express, OE, vol. 30, no. 22, pp. 39860–39867, Oct. 2022, doi: 10.1364/OE.466321.