Abstract
3D-Photonic crystals (opals) based on polystyrene (PS) colloidal nanospheres are being characterized by scanning near-field optical microscopy (SNOM). These crystals offer a huge potential for controlling both the spontaneous emission of embedded light sources and the propagation of light itself. In a first stage, we are primarily interested in the light transmission and reflection by this kind of structures at different wavelengths. Three different kind of opals are studied in this work exhibiting fee structure with 583, 834 and 907 nm of lattice parameter in the [lll]-plane which induce photonic band-gaps centred at 980, 1470 and 1600 nm respectively. The far-field transmission has been also measured for opals with different thicknesses (from 7 up to 70 PS-sphere layers). The absorption at such gap increases with the number of PS-sphere layers by a factor e each eight layers, approximately. The near-field transmission and reflection have been studied at different wavelengths by a tuning fork based SNOM in constant gap operation mode [1]. The optical SNOM images can be acquired simultaneously with topography ones, as shown in the figure, which enables their comparison [2]. Several wavelengths have been selected for the study of each opal corresponding to the first and second order band-gap and its vicinities. The topography, reflection, and transmission images are compared where we can conclude that the reflectance images are correlated with the surface ordering of the PS-spheres while in transmission images such correlation depends on the excitation wavelength (not show). On the other hand, reflection and transmission images present identical sing of the optical contrast produced by the surface spheres. This fact reveals the photonic nature of effects since a sign inversion is expected on topographical features.
© 2007 IEEE
PDF ArticleMore Like This
Wico C.L. Hopman, Kees O. van der Werf, and René M. de Ridder
IWF7 Integrated Photonics and Nanophotonics Research and Applications (IPR) 2007
Philip J. Harding, Tijmen G. Euser, and Willem L. Vos
CK_28 The European Conference on Lasers and Electro-Optics (CLEO/Europe) 2007
T. Merz and R.W. Kessler
6631_33 European Conference on Biomedical Optics (ECBO) 2007