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HL: Halbleiterphysik

HL 26: II-VI semiconductors II

HL 26.4: Talk

Tuesday, March 28, 2006, 16:00–16:15, POT 51

Whispering gallery modes in hexagonal nanocavities – theory vs. experiment. — •Thomas Nobis, Andreas Rahm, Michael Lorenz, and Marius Grundmann — Universität Leipzig, Fakultät für Physik und Geowissenschaften, Linnéstraße 5, D-04103 Leipzig

Concerning nano-photonics, zinc oxide (ZnO) nanostructures are frequently envisioned as resonator cavities in future optical devices, such as nanolasers. Thus, a precise understanding of their optical modes is strongly necessary. In this work we analyzed the lateral optical modes, so-called whispering gallery modes (WGMs), of ZnO nanopillars grown by pulsed laser deposition with diameters around 800 nm. The regular hexagonal cross-section of the pillars naturally defines a two-dimensional (2D) dielectric cavity with the light circulating inside being totally internally reflected. Our analysis includes detailed numerical simulations of hexagonal WGMs solving the 2D Helmholtz-equation with respect to resonant wave numbers, line widths, mode patterns, polarization, mode degeneracy and spectral dispersion. Utilizing our numerical results we are able to simulate characteristic resonance lines of individual ZnO nanopillars in perfect agreement with the experiment [1]. As a result we can extract the birefringence of single pillars out of their WGM spectrum. Hence, the whispering gallery effect has been utilized to detect optical constants of nano-sized samples.

[1] Th. Nobis and M. Grundmann, Phys. Rev. A, in press