Berlin 2014 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 61: Photonics II
Q 61.4: Vortrag
Freitag, 21. März 2014, 14:45–15:00, UDL HS3038
Group Theory of Circular-Polarisation Effects in Chiral Photonic Crystals with Four-Fold Rotation Axes — •Matthias Saba1, Mark D. Turner2, Min Gu2, Klaus Mecke1, and Gerd E. Schröder-Turk1 — 1Theor. Physik, Friedrich-Alexander Universität Erlangen-Nürnberg, Germany — 2CUDOS & Centre for Micro-Photonics, Swinburne University of Technology, Australia
We use group or representation theory and scattering matrix calculations to derive analytical results for the band structure topology and the scattering parameters, applicable to any chiral photonic crystal with body-centered cubic symmetry I432 for circularly-polarised incident light. We demonstrate in particular that all bands along the cubic [100] direction can be identified with the irreducible representations E±, A and B of the C4 point group. E+ and E− modes represent the only non-interacting transmission channels for plane waves of right (E−) and left (E+) circular polarization, respectively. Scattering matrix calculations provide explicit relationships for the transmission and reflectance amplitudes through a finite slab which guarantee equal transmission rates for both polarisations and vanishing ellipticity below a critical frequency, yet allowing for finite rotation of the polarisation plane. All results are verified numerically for the so-called 8-srs geometry, consisting of eight interwoven equal-handed dielectric Gyroid networks embedded in air. The combination of vanishing losses, vanishing ellipticity, near-perfect transmission and optical activity comparable to that of metallic meta-materials makes this geometry an attractive design for nanofabricated photonic materials.