Fig. 10
From: Recent advancements of metalenses for functional imaging
Spectrometer using metasurface: a Schematic of a conventional spectrometer. b Schematic of compact spectrometer using metasurface, and phase profile of metasurface compensating for monochromatic aberration. c (left) Structure of unit cell, and (top right and bottom) simulated phase according to TE and TM polarization, where the black curve represents Dx-Dy with the same phase for TE and TM polarization. d Intensity distribution when light with wavelength difference of 1.25 nm is incident with TE and TM polarization. a-d are reproduced with permission [156] (Copyright 2018, Springer Nature). e Schematic of a doublet metalens for on-axis and off-axis incidence, where the spot size is small owing to monochromatic aberration compensation (scale bar: 2 μm). Reproduced with permission [157] (Copyright 2016, Springer Nature). f (left) SEM image of fabricated metalens, and schematic of fabricated device with four separate metalenses. (right) R and L refer to the helicity of light focused by each metalens, and 1 and 2 indicate the parameters used for the lens design (scale bar: 5 mm). g Compact spectrometer that combines a metalens and a CMOS camera. f and g are reproduced with permission [158] (Copyright 2017, AIP Publishing)