Nanohybrids investigation by waveguide SNOM illumination mode Nayla El-Kork n , Paul Moretti, Bernard Jacquier Universite´ de Lyon, F-69622 Universite´ Lyon 1. Domaine Scientifique de la Doua, Bˆ atiment Alfred Kastler, 10 rue Ada Byron, 69622 Villeurbanne cedex-France. Laboratoire de Physico Chimie des Mate´riaux luminescents, CNRS UMR 5620, France article info Article history: Received 23 August 2010 Received in revised form 17 March 2011 Accepted 24 March 2011 Available online 14 April 2011 Keywords: Optical waveguides Nanohybrids Near field optical microscopy Guided mode evanescent wave excitation abstract We demonstrate how optical waveguides can serve as a high resolution illumination source to image hybrid nano-objects in near field optical microscopy. Nanohybrid particles deposited on the surface of glass waveguides are imaged in terms of topography, scattering and fluorescence. & 2011 Elsevier B.V. All rights reserved. 1. Introduction The use of evanescent waves in optical analysis devices, imaging microscopy and sensors has a unique advantage over other methods, since it relies on the wave’s unique localized nature. Such a property permits a better selection and efficient illumination of dispersed objects on a surface in addition to an enhanced sensitivity. This is particularly true for guided wave configurations, where the photonic density can reach very high values. Imaging devices or miniaturized sensors relying on this principle are being developed both commercially and in scientific laboratories [1]. Indeed, the demand for evanescent wave micro- nano-sensors has significantly increased in the last few years, with the strong development of nanotechnology in fields such as medical and biological sciences. In that sense, the evanescent field of a propagating mode can be used as an illumination source for the excitation of attached elements on the surface of the sensor [2,3]. Besides, the same principle is also applied in total internal reflection microscopy (TIRF) or reverse symmetry waveguide sensing [4]. Waveguide optical sensors also form an excellent tool for the investigation of surface-bound molecules. In this case, the fluorescing material to which the studied analyte is attached is brought into the evanescent field of a waveguide mode, whose specific wavelength corresponds to one which is in the excitation region of the fluorescence dye; the emitted fluorescence photons can then be used to construct an image, which provides the needed information about the analyte [5]. Near field optical microscopy is a powerful tool allowing the visualization of physical or biological objects with sub-wavelength resolution [6]. Coupling between evanescent waves and near field optical Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jlumin Journal of Luminescence Fig. 1. Absorption (blue line) and normalized emission spectra of hybrid nano- particles in solution (green line), and dispersed on a glass plate (red line); the inset shows the structure of a nanoparticle (a 3D cross-section is pictured; particles are usually of spherical shape). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) 0022-2313/$ - see front matter & 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jlumin.2011.03.053 n Corresponding author. Present address: Khalifa University of Science, Technology and Research—Sharjah Campus P.O. Box 573 Sharjah UAE. Tel.: þ971 5 67 89 25 17; fax: þ971 6 56 11 789. E-mail addresses: nayla.elkork@kusar.ac.ae (N. El-Kork), paul.moretti@wanadoo.fr (P. Moretti), jacquier@pcml.univ-lyon1.fr (B. Jacquier). Journal of Luminescence 131 (2011) 2224–2229