Chinese Optics Letters, 2021, 19 (2): 023601, Published Online: Feb. 4, 2021
Doublet achromatic metalens for broadband optical retroreflector Download: 913次
Abstract
A retroreflector that reflects light along its incident direction has found numerous applications in photonics, but the available metasurface schemes suffer from the issue of narrow bandwidth and/or a single angle of incidence. Here, a retroreflector using double layers of achromatic gradient metasurfaces is reported, which can realize retroreflection over a continuous range of incidence angles within a wide spectral band. The first metasurface serves as a transmissive achromatic lens that performs a broadband spatial Fourier transform and its inverse, while the second metasurface works as a reflective achromatic lens that undergoes wavelength- and position-dependent phase dispersions. Using this design strategy, a near-infrared retroreflector comprised of silicon nanopillars with the cross sections of square pillars and square holes is numerically demonstrated, providing a high-performance retroreflection for polarization-independent incident light waves over a continuous range of incidence angles from 0° to 16° within an extremely broad wavelength range between 1.35 and 1.95 m. The scheme herein can offer a design strategy of broadband retroreflectors and impact numerous photonics applications.
Ming Deng, Tangxuan Ren, Jian Wang, Lin Chen. Doublet achromatic metalens for broadband optical retroreflector[J]. Chinese Optics Letters, 2021, 19(2): 023601.