Regensburg 2004 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 12: Poster I

HL 12.25: Poster

Montag, 8. März 2004, 16:30–19:00, Poster A

Light scattering in thin opal films — •Sergei Romanov — Institute of Materials Science and Department of Electrical and Information Engineering, University of Wuppertal, 42097 Wuppertal, Germany

Reflectance and transmission are conventionally used to measure light interaction with photonic crystals (PhCs), whereas the light scattered off the incidence direction is neglected. In this work the scattering was used as an independent tool to study the light propagation in slightly disordered three-dimensional PhCs. In such crystals the regime of weak scattering is realised, when scattered photons experience only one collision along their paths, i.e. they mimic light emitted by an internal light source.

The intensity of light scattered by thin opal films in forward and backward configurations was studied as a function of wavelength and direction. It was shown that diffraction-related minima of forward scattered light do not depend on the actual lightpath, but correspond to directions of the incidence and detection with respect to (111) planes. Angle diagrams of the scattered light were assigned to the resonant scattering, moreover, they show a modulation by shadows of respective bandgaps. Oppositely, the backscattering appears more effective at bandedges of the Bragg gap.

As an example, the light scattering was used to characterise the light propagation across the PhC heterojunction.