Fig. 8
From: Recent advancements of metalenses for functional imaging
Chromatic aberration compensation lens: a SEM image of fabricated achromatic metalens with NA = 0.106. (top left) Entire metalens (scale bar: 10 μm), and (top middle and right) magnified view of inset of 1st image (scale bar: 500 nm). (bottom) Experimental light intensity profile according to incident light at each wavelength. White dashed lines indicate the focal plane. Reproduced with permission [99] (Copyright 2018, Springer Nature). b (top left) Achromatic metalens using CP light. (top right) MgO meta-atom with height H, width W, and length L on a uniform periodic P \(\times\) P substrate. (bottom left) Unit cell of simple metalens and hybrid metalens. θ is the angle that satisfies the phase according to the geometric PB phase method. (bottom right) top view of simple and hybrid metalenses with radius R. Reproduced with permission [134] (Copyright 2021, Springer Nature). c Schematic of an achromatic metalens that satisfies Eq. (4). The metalens is designed such that wavepackets from different locations can reach the focus simultaneously. Yellow line indicates a spherical wavefront. Reproduced with permission [135] (Copyright 2018, Springer Nature). d Schematic of a multilayer dielectric metalens operating at multiple wavelengths. Each layer provides a required hyperbolic phase profile for each different wavelength. Reproduced with permission [136] (Copyright 2018, American Chemical Society). e (left) Schematic of hybrid metalens that combines a phase plate and metalens to compensate for chromatic aberration while improving focusing efficiency. (right) Unit cell of hybrid metalens. Reproduced with permission [137] (Copyright 2020, Springer Nature). f Hybrid achromatic metalens (scale: cm). (left) Chromatic aberration correction and (right) spherical aberration correction. Reproduced with permission [138] (Copyright 2021, Optica Publishing Group). g Schematic of a dual-layer achromatic metalens (DAML). Planoconvex metalens, planoconcave metalens, and cross-section of DAML. Reproduced with permission [139] (Copyright 2020, Optica Publishing Group)