Decoupling optical function and geometrical form using conformal flexible dielectric metasurfaces

Abstract

Physical geometry and optical properties of objects are correlated: cylinders focus light to a line, spheres to a point and arbitrarily shaped objects introduce optical aberrations. Multi-functional components with decoupled geometrical form and optical function are needed when specific optical functionalities must be provided while the shapes are dictated by other considerations like ergonomics, aerodynamics or aesthetics. Here we demonstrate an approach for decoupling optical properties of objects from their physical shape using thin and flexible dielectric metasurfaces which conform to objects' surface and change their optical properties. The conformal metasurfaces are composed of silicon nano-posts embedded in a polymer substrate that locally modify near-infrared (λ=915 nm) optical wavefronts. As proof of concept, we show that cylindrical lenses covered with metasurfaces can be transformed to function as aspherical lenses focusing light to a point. The conformal metasurface concept is highly versatile for developing arbitrarily shaped multi-functional optical devices.

Multiwavelength polarization-insensitive lenses based on dielectric metasurfaces with meta-molecules

“…The posts' height can be chosen such that at a certain wavelength the whole 2π phase shift is covered, while keeping the transmission amplitude high. Each nanopost has multiple resonances that are excited and contribute to the scattered field with various strengths [32]. Since many resonances play an important role in the response of nanoposts, we find that explaining their response based on these resonances does not provide an intuitive understanding of their operation.…”

“…2(a), center] was chosen, because Research Article it has more parameters to control the phases at two wavelengths almost independently. Due to the weak coupling between the nanoposts [10], they behave like individual scatterers with large cross-section, as shown in our previous works [10,11,32]. As molecules consisting of multiple atoms form the units for more complex materials, we call these unit cells with multiple meta-atoms meta-molecules.…”

“…Since many resonances play an important role in the response of nanoposts, we find that explaining their response based on these resonances does not provide an intuitive understanding of their operation. Instead, these nanoposts can be better understood as truncated multimode waveguides [32,33]. To design a metasurface that works at two different wavelengths, a unit cell consisting of four different nanoposts [ Fig.…”

Reconfigurable systems for multifunctional electronics

“…As a proof of concept, a convex glass cylinder covered by a metasurface can function as an aspherical lens to focus light to a point. 66 When the frequency enters the light regime, the scaling law that the resonant frequency scales inversely with the characteristic dimension of the structure breaks down, because the kinetic energy and inertia of electron cannot be neglected as those in low frequency regimes. The localized surface plasmon resonance (LSPR) in each unit cell and the interaction of LSPR between cells affect resonance and thus the absorption of light, as thoroughly discussed in several review papers.…”

Design of mechanically robust metasurface lenses for RGB colors

“…In this letter, aimed to solve these problems, we propose a general approach to design a solid metasurface lens working for multiple colors, which in principle could be extended for any frequency regime. Low index dielectric claddings for metasurface devices have been explored before to acquire scalability and flexibility 29,30,[47][48][49][50][51] . But the effect of their structural features to the device performance has been rarely discussed.…”