Fig. 4
From: Recent advancements of metalenses for functional imaging
Multifunctional and tunable metalenses. Multifunctional metalenses: a Measured normalized intensity distribution on xz-plane of varifocal metalens. θ represents polarization angle of incident light. Reproduced with permission [63] (Copyright 2019, American Chemical Society). b Schematic of nonlinear intensity multifunctional metalens. (inset) Transmission electron microscopy image of metallic quantum wells (scale bar = 5 nm). c Captured images for incident light intensity of (top) 5 GW/cm2 and (bottom) 20 GW/cm2 (scale bar = 200 μm). (b) and (c) are reproduced with permission [117] (Copyright 2022, Wiley-VCH). d Interleaving method for multiplexing multiple OAM modes in metalens. Reproduced with permission [118] (Copyright 2022, Springer Nature). Tunable metalenses: e Imaging experiment results of varifocal metalens for varying applied voltages. Voltages of 0 and 6 V produced clear images at distances of 692 and 732 μm, respectively (scale bar = 10 μm). Reproduced with permission [64] (Copyright 2018, American Chemical Society). f Experimental intensity profile of bifocal metalens on xz-plane for (top) LCP and (bottom) RCP incident light. Reproduced with permission [119] (Copyright 2021, Wiley-VCH). g Stretching condition of graphene-oxide-based metalens. This metalens is stretched uniformly, and the stretch ratio is 1.1 times. Reproduced with permission [120] (Copyright 2021, American Chemical Society). h Focal length change of GSST-based metalens. This metalens has different focal lengths in amorphous and crystalline states. i Measured focal spot profiles for (left) amorphous and (right) crystalline states. (inset) Captured images of focal spots. h and i are reproduced with permission [121] (Copyright 2021, Springer Nature)