Berlin 2008 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 53: Optical properties

HL 53.11: Talk

Friday, February 29, 2008, 13:15–13:30, EW 201

Three-dimensionally Confined Optical Modes in Microtube Bottle Resonators — •Hagen Rehberg, Christian Strelow, Christoph M. Schultz, Holger Welsch, Christian Heyn, Detlef Heitmann, and Tobias Kipp — Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg

We report on three-dimensional confinement of optical modes in microtube ring resonators induced by a radius modulation. Our microtubes are fabricated by the use of the self-rolling mechanism of thin strained bilayers. The radius modulation is caused by local additional windings forming two rings around the tube. Spatially resolved micro-photoluminescence measurements show modes which are axially confined between the rings. We observe axial field distributions which resemble standing waves in an optical bottle with intensity enhancements at the classical turning points. The confining mechanism is discussed in terms of a squeezing of the tube by the additional rings. Calculations using an adiabatic approximation define a quasi-potential for the slow propagation along the tube axis. This quasi-potential induced by the fast propagation around the tube axis depends strongly on the radius of the tube. Correlations of both calculations and measurements give an insight into the actual size and form of the radius modulation. The reported technique of radius modulation allows a tailoring of the mode energies and to realize a two-port device which can be used as an optical filter. We acknowledge financial support by the Deutsche Forschungsgemeinschaft via SFB 508 and GrK 1286 "Functional Metal-Semiconductor Hybrid Systems".