21‐4: Plasmonic Nanostructures Array with Correlated Disorder for Augmented Reality

Abstract

Augmented reality makes life easier for users in different domains like education, industry, and medicine. Head-up displays (HUD), used in the automotive domain, can be seen as one early development of augmented reality systems. HUD consists in reflecting a colored display on a transparent glass plate which indicates driving relevant information to the driver. In order to reduce display consumption and/or to obtain sufficient contrast in case of sunny weather, it is necessary to increase the plate reflectance at image color wavelengths. More precisely, the challenge is to develop a plate with simultaneously high reflectance, high angular tolerance and high transparency, providing a clear reflected picture and a clear view of the landscape behind the plate. Among different technologies, localized plasmonics, based on noble metal nanoparticles (NPs) resonances, enables local modification of colors and versatile HUD plate designs [1,2]. Usually, designs of resonant NPs arrays are performed considering periodic layout, more suitable for current numerical tools. However, disordered arrangement presents several advantages: attenuated light diffraction, possible low cost and large scale fabrication, versatile design. (a) (b) (c) (d) Fig. 1. Fabricated samples: (a) SEM images of the square lattice (left) and correlated disorder (right) NPs arrangements. Backlit photography of the sample with pairs of "Sq" and "Rd" arrays with 200nm (Sq) and 216nm (Rd) average interparticle distances and different ellipses diameters (formatted as "a x b" given in nm). (b) Reflectance and transmittance spectra for Sq and Rd arrays with identical NPs and both polarizations. (c,d) Reflectance and transmittance peaks spectral positions of all arrays and different angles for both polarizations.Here we first experimentally show that subwavelength period square lattice NPs arrays present similar reflection and transmission properties to the corresponding disordered ones with the same spatial density, regardless of the resonance wavelength, the polarization (p or s) and the angle of the incident light (Fig. 1). The resonance peaks are tuned by modifying the size of the NPs. The reflectance maxima follow the plasmonic resonance intensity, dependent on the wavelength. The targeted color in this work is amber, corresponding to 590nm wavelength. NPs resonant at 590nm are considered in the following. Then, by decreasing the NPs spatial density to increase the plate transparency, possible diffraction orders and surface lattice