Regensburg 2007 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 18: Photonic crystals I
HL 18.6: Talk
Tuesday, March 27, 2007, 12:00–12:15, H13
Strong Circular Dichroism from Chiral 3D Photonic Crystals — •Michael Thiel1, Manuel Decker2, Martin Wegener1, Stefan Linden2, and Georg v. Freymann2 — 1Institut für Angewandte Physik, Universität Karlsruhe (TH), Wolfgang-Gaede-Straße 1, D-76131 Karlsruhe — 2Institut für Nanotechnologie, Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft, D-76021 Karlsruhe
Chiral photonic crystals allow for photonic stop bands for circularly polarized light connected with pronounced circular dichroism[1] which can potentially be used for applications, e.g., as compact *thin-film* optical diodes[2]. We have fabricated high-quality polymeric 3D spiral photonic crystals[3] via direct laser writing[4]. The measured transmittance spectra of these low-index contrast structures reveal spectral regions where the transmittance is below 5 % for one circular polarization and larger than 95 % for the other -- for just eight lattice constants along the propagation direction[1]. These polarization stop bands occur if the pitch of the light spiral matches the pitch of the dielectric spiral. As expected from the symmetry, the transmittance spectra are closely similar if both the sense of rotation of the dielectric spirals and that of the incident light field are changed simultaneously. Our experimental results agree well with theory. Additionally, we present a novel chiral 3D layer-by-layer structure as an alternative to the discussed circular dichroitic 3D spiral photonic crystals.
[1]*M. Thiel et. al., Adv. Mater., in press (2006). [2]*J. Hwang et. al., Nature Mater., 4, 383 (2005). [3]*K. K. Seet et. al., Adv. Mater., 17, 541 (2005). [4]*M. Deubel et. al., Nature Mater., 3, 444 (2004).