Research on broadband achromatic metalenses

Abstract

<p indent=0mm>Nowadays, metasurfaces can be made into various classical and non-classical devices due to their plentiful physical connotation and application value. To optimize the design method of broadband continuous achromatism, we rely on the geometric phase and resonance phase of the metasurface to realize the separation of the wavelength-independent basic phase and the wavelength-dependent chromatic aberration phase in the optical device, and design the achromatic reflection focusing mirror and reflector in the near-infrared band. Next, we use the GaN nanopillars and its inverse structure which is transparent under visible light to prepare an achromatic metalens in the visible light frequency band, and for the first time achieve full-color imaging and video shooting based on metalenses. Faced with the problem that the numerical aperture and the clear aperture cannot be large at the same time, we bring in the system of metalens array, which not only obtains the improvement of the imaging effect, but also realizes the light field imaging, which greatly enriches the imaging of the metalens content and function. Recently, by integrating a metalens array with a nonlinear crystal, we demonstrate a 100-path spontaneous parametric down-conversion photon-pair source in a 10 × 10 array, which shows promise for high-dimensional entanglement and multiphoton-state generation. This quantum light source can realize both high-dimensional entanglement and multiphotons. The metalens has introduced new systems and new physical effects in the fields of optical imaging and quantum optics.