Broadband continuous achromatic and super-dispersive metalens in near-infrared band

For a long time, dispersion is always an important issue in optics. In recent decades, metasurfaces with the excellent optical field manipulating performance have provided a new solution to realize dispersion management. However, existing strategies usually rely on numerous simulations to select appropriate nanostructures, which are not intuitive and time-consuming. Here, we theoretically analyzed the dispersion controlling mechanism of nanostructured metasurfaces based on the effective refractive index theory. By simultaneously controlling the basic phase and the phase–frequency slope, phase profiles of the dispersion-tailored metalens can be reproduced. Adopting this strategy, continuous achromatic and super-dispersive cylindrical metalenses were designed using a transmissive dielectric metasurface with simple nanostrips. Simulated result shows that, in the near-infrared band from 1200 to 1600 nm, the chromatic dispersion can be reduced to less than a quarter of the regular one for the achromatic metalens, while it has about two times increase for the super-dispersive metalens. In addition, the two different types of metalenses have high efficiency of above 60% and narrow full width at half maximum near the diffraction limit over the 400 nm near-infrared band. These extraordinary properties offer a broad application prospect for the metalens in the field of highly integrated imaging, multispectral detection, tomography, etc.