title: Optical Response of Silver Nanoneedles on a Mirror.
abstract: Plasmonic properties of metal nanostructures are appealing due to their potential to enhance photovoltaics or sensing performance. Our aim was to identify the plasmonic characteristics of silver nanoneedles on a reflective layer in the polarized optical response. Experimental ellipsometry results are complemented by finite-difference time-domain (FDTD) calculations. Plasmon resonances on the nanoneedles can indeed be observed in the polarized optical response. This study reveals the details of the complex antenna-like behaviour of the nanoneedles which gives an agreement between experiment and FDTD simulation. The simulations show that the plasmon resonances lead to an effective negative refractive index, originating from the negative refractive index of the nanoneedles in combination with its supporting substrate, i.e. a mirror. This original study of a complex plasmonic system by ellipsometry and FDTD has great relevance for applications, making use of intricate light matter interaction.
authors.affiliation: Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands.
authors.forename: Arjan
authors.initials: A
authors.lastname: Keeman
authors.affiliation: Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: E Stefan
authors.initials: ES
authors.lastname: Kooij
authors.affiliation: Nanophotonics-Physics of Devices, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands.
authors.forename: Dick
authors.initials: D
authors.lastname: van Dam
authors.affiliation: Solar Energy, Energy Research Center of the Netherlands (ECN), High Tech Campus Building 5, 5656 AE Eindhoven, The Netherlands ; Department of Applied Physics, Plasma & Materials Processing, Eindhoven University of Technology (TU/e), P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Ruud E I
authors.initials: RE
authors.lastname: Schropp
authors.affiliation: Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands ; Nanophotonics-Physics of Devices, Debye Institute for Nanomaterials Science, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands.
authors.forename: Marcel
authors.initials: M
authors.lastname: Di Vece
keywords: Ellipsometry; FDTD; Nanoneedle; Silver