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Compact Aberration‐Corrected Spectrometers in the Visible Using Dispersion‐Tailored Metasurfaces
Author(s) -
Zhu Alexander Y.,
Chen Wei Ting,
Sisler Jared,
Yousef Kerolos M. A.,
Lee Eric,
Huang YaoWei,
Qiu ChengWei,
Capasso Federico
Publication year - 2019
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.201801144
Subject(s) - optics , cardinal point , spectrometer , dispersion (optics) , planar , materials science , focal length , spectral resolution , resolution (logic) , physics , lens (geology) , computer science , spectral line , computer graphics (images) , astronomy , artificial intelligence
The spectral resolution and range of conventional spectrometers are typically limited by optical aberrations of their focusing elements, mainly due to chromatically induced astigmatism and an intrinsically curved focal plane. Traditional approaches to overcome this challenge require additional optical components which introduce significant bulk and design complexity to the system and prevent easy integration with portable devices. Here a single planar off‐axis focusing metalens consisting of subwavelength TiO 2 nanofins whose focal spots lie along a plane and undergo minimal focal spot broadening for almost 200 nm across the visible spectrum is demonstrated. This allows us to achieve a miniature aberration‐corrected spectrometer with nanometer spectral resolution, while having a beam propagation distance of only 4 cm to the camera plane. This is achieved by dispersion engineering: tailoring the phase, group delay (GD) and GD dispersion of the metalens. This approach is general and can also be used to introduce customized functionalities to the metalens such as a linear dispersion in the frequency domain with minimal additional overhead.