2, Nanjing University, Nanjing, , China
3, National Taiwan University, Taipei, , Taiwan
Metasurfaces have shown great abilities on controlling light properties on demand at a subwavelength resolution . They therefore are very promising for the development of flat optical components. However, the building blocks of metasurfaces usual exhibit strong dispersion effect, which results in chromatic aberration apparently [2-4]. For addressing this issue, we come out a design principle by incorporating geometric phase with integrated-resonant unit elements for realizing specific phase compensation at corresponding spatial position . The basic building blocks of the metasurface are gold nano-rods and their assemblies. The metal-dielectric-metal structural configuration is implemented to access a cavity-like resonance for the improvement of working efficiency. As a proof of concept, two reflective achromatic metasurface devices (focusing metalens and beam deflector) are demonstrated for circularly-polarized incident light. They are capable of eliminating the chromatic effect over an ultra-broad continuous bandwidth in near-infrared (from 1200 nm to 1680 nm). To our best knowledge, this is the state-of-the-art demonstration for realizing truly achromatic devices with flat optical metasurfaces. The working wavelength can be further pushed to the visible spectrum through replacing the metallic structures by high-index dielectric unit-elements . Our design principle paves a way to flexibly engineer the phase dispersion, benefitting the development of feasible application for full-color imaging systems and detections, just named a few.
1. H.-H. Hsiao, C. H. Chu, and D. P. Tsai, "Fundamentals and applications of metasurfaces," Small Methods 1, 1600064 (2017).
2. P. Wang, N. Mohammad, and R. Menon, "Chromatic-aberration-corrected diffractive lenses for ultra-broadband focusing," Sci. Rep. 6, 21545 (2016).
3. E. Arbabi, A. Arbabi, S. M. Kamali, Y. Horie, and A. Faraon, "Controlling the sign of chromatic dispersion in diffractive optics with dielectric metasurfaces," Optica 4, 625-632 (2017).
4. P. C. Wu, W.-Y. Tsai, W. T. Chen, Y.-W. Huang, T.-Y. Chen, J.-W. Chen, C. Y. Liao, C. H. Chu, G. Sun, and D. P. Tsai, "Versatile polarization generation with an aluminum plasmonic metasurface," Nano Lett. 17, 445-452 (2017).
5. S. Wang, P. C. Wu, V.-C. Su, Y.-C. Lai, C. Hung Chu, J.-W. Chen, S.-H. Lu, J. Chen, B. Xu, C.-H. Kuan, T. Li, S. Zhu, and D. P. Tsai, "Broadband achromatic optical metasurface devices," Nat. Commun. 8, 187 (2017).
6. B. H. Chen, P. C. Wu, V.-C. Su, Y.-C. Lai, C. H. Chu, I. C. Lee, J.-W. Chen, Y. H. Chen, Y.-C. Lan, C.-H. Kuan, and D. P. Tsai, "GaN metalens for pixel-level full-color routing at visible light," Nano Lett. 17, 6345-6352 (2017).