Session Chair: Romain Quidant, The Institute of Photonic Sciences
10:30am - 11:00am Keynote
Robust Structural Colors with Disordered Metasurfaces
Harvard University, United States
We develop a new approach based on large scale network metasurfaces, which combine de-alloyed subwavelength structures at the nanoscale with loss-less, ultra-thin dielectrics coatings. By using theory and experiments, we show how sub-wavelength dielectric coatings control a mechanism of resonant light coupling with epsilon-near-zero (ENZ) regions generated in the metallic network, manifesting the formation of saturated structural colors that cover a wide portion of the spectrum. Ellipsometry measurements demonstrate the efficient observation of these colors even at angles of 70 degrees. 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.
Collaborations with Henning Galinski, Andrea Fratalocchi, Gael Favraud, Hao Dong, Juan S. Totero Gongora, Gregory Favaro, Max Dobeli, Ralph Spolenak are gratefully acknowledged. This work was supported by AFOSR contract FA9550-12-1-0289
 H. Galinski, et al. Light: Science & Applications (2017) 6, e16233; doi: 10.1038/lsa.2016.233.
11:00am - 11:30am Invited
Vivid and High Resolution Color Printing with Resonant Nanostructures
1Singapore University of Technology and Design, Singapore; 2Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore
Nanostructured materials are appealing substitutes for dyes because they can produce colors that do not photobleach, achieve unprecedented resolution in printing, and simplify the printing of colors by removing sequential inking steps. Initial demonstrations of color prints with plasmonic nanostructures of silver, gold, and aluminum have identified several comparative advantages over other types of color generating schemes, e.g. dyes and diffractive structures. However, the remaining drawback of plasmonic nanostructured color has been the limited color gamut that lead to poor saturation and vividness. As resistive losses in metal prevent high Q-factor resonances in these nanostructures, replacing metal with high index dielectrics could broaden the achievable color gamut. In this talk we will provide a review of the recent progress in plasmonic color printing and discuss the promise of dielectric nanostructures in CMOS compatible high resolution and vivid color printing.
11:30am - 12:00pm Invited
Enhanced Light Matter Interaction with Silicon Nanostructures
Aix-Marseille University, National Center for Scientific Research (CNRS), Centrale Marseille, Institute Fresnel, France
In the visible or NIR spectrum, subwavelength sized particles composed of semi-conductors can resonantly interact with light . Interestingly, they feature electric and magnetic resonances that make them ideal candidates to design novel light nanocavities with strong Purcell enhancements  or to boost the chirality of light emitted by chiral emitters .
We fabricated sets of silicon nanogap antennas with 20 nm and 30 nm gaps that maximize the field inside the gap. We followed two techniques to measure the fluorescence enhancement, namely the fluorescence burst analysis and fluorescence correlation spectroscopy. In both cases, we measured fluorescent enhancements above 200 fold . This fluorescence enhancement is accompagnied by a 3600 fold decrease of the detection volume that allowed us to detect individual molecules at micromolar concentration .
The resonant interaction between silicon particles and light provides structural colours. By controlling the size of the particles, one can modify the scattering spectrum and the resulting structural colour. Based on this concept, we fabricated all-dielectric metasurfaces to imprint coloured images on a surface . We coated a silicon film on a silica substrate and we etched silicon particles of different diameters. By combining dark field spectroscopy and numerical anlysis, we retrieved the RGB parameters of each silicon particle size. We highlighted the interest of this tehcnique by imprinting a Mondrian’s painting at a 1 :1200° scale by using silicon particles only . Arrays of optically resonant dielectric particles are also interesting to conceive spectral filters for image sensors.
 A. I. Kuznetsov et al., Science 354, aag2472 (2016)
 X. Zambrana-Puyalto et al., Phys. Rev. B 91, 195422 (2015)
 X. Zambrana-Puyalto et al., Nanoscale 8, 10441-10452 (2016)
 R. Regmi al., Nano Lett. 16, 5143−5151 (2016)
 J. Proust et al., ACS Nano 10, 7761–7767 (2016)