Scalable, ultra-resistant structural colors based on network metamaterials

Abstract

Structural colors have drawn wide attention for their potential as a future printing technology for various applications, ranging from biomimetic tissues to adaptive camouflage materials. However, an efficient approach to realize robust colors with a scalable fabrication technique is still lacking, hampering the realization of practical applications with this platform. Here, we develop a new approach based on large-scale network metamaterials that combine dealloyed subwavelength structures at the nanoscale with lossless, ultra-thin dielectric coatings. By using theory and experiments, we show how subwavelength dielectric coatings control a mechanism of resonant light coupling with epsilon-near-zero regions generated in the metallic network, generating the formation of saturated structural colors that cover a wide portion of the spectrum. Ellipsometry measurements support the efficient observation of these colors, even at angles of 70°. The network-like architecture of these nanomaterials allows for high mechanical resistance, which is quantified in a series of nano-scratch tests. With such remarkable properties, these metastructures represent a robust design technology for real-world, large-scale commercial applications.

Waveguide modes in Weyl semimetals with tilted dirac cones

“…Depending on the polarization of the EM wave relative to the crystalline axes, a WS can be tuned to exhibit a metallic or insulating type of EM response, as described by its permittivity tensor . This is reflected in the real parts of the appropriate components of changing sign, or vanishing altogether, as occurs in epsilon-near-zero (ENZ) materials [37][38][39][40][41][42][43][44][45][46][47][48][49]. Various peculiar effects can arise in materials exhibiting an ENZ response [46], including light tunneling, vanishing group velocity, and perfect absorption [43].…”

Flexible, Large‐Area Covert Polarization Display Based on Ultrathin Lossy Nanocolumns on a Metal Film

“…The reported experimental demonstrations are mainly achieved by elaborate processes (using e‐beam lithography or focused ion beam lithography) to define arrays of nanopatterns, however, practical use of such processes is restricted to overall lateral dimensions of less than a few millimeters. For realistic applications occurring in many aspects of daily life (including quick response (QR) codes, banknotes, identity cards, medicine, and consumer goods), cost, throughput, areal coverage, and flexibility/conformability are important considerations . Angular robustness is also one of the key factors for the successful recognition of encrypted information printed on curved or complex surfaces .…”

Near-Field Coupling and Mode Competition in Multiple Anapole Systems

“…We performed fully-dispersive three-dimensional FDTD simulations using our home-made simulator NANOCPP [24][25][26][27][28][29]. In our simulations, the computational domain was organized as follows: the z-aligned nanodisks were placed at the centre of a 2 µm × 2 µm × 1 µm box, with uniaxial perfectly matched layer (UPML) boundary conditions emulating an open system [30].…”