Hannover 2010 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 67: Photonics IV

Q 67.1: Vortrag

Freitag, 12. März 2010, 14:00–14:15, F 128

Controlling the optical properties of single molecules by optical confinement in a tunable microresonator (exchanged with Q 55.36) — •Raphael Gutbrod, Alexey Chizhik, Anna Chizhik, Dmitry Khoptyar, Sebastian Bär, and Alfred J. Meixner — Institute of Physical and Theoretical Chemistry, University of Tübingen

Optical single-mode microresonators are structures which confine light to a small region in the range of half a wavelength. The broadband fluorescence emission and the decay lifetimes of single molecules are altered by the optical mode structure. In the tunable microresonator we present here, the resonator length can be changed reversibly with piezoelectric elements to a distinct position corresponding to a specific emission wavelength. The local mode structure of the electromagnetic field is changed at this position which results in a redistribution of the fluorescence and a modification of the lifetime for the same single molecule. The results obtained are in good agreement with the semi-classical model we developed for a better understanding of the coupling mechanisms between a single molecule and the cavity. The radiative coupling of the molecule to the electromagnetic field is also determined by the orientation of its transition dipole moment. Focusing a radially polarized doughnut mode laser beam (cylindrical vector beam) via a high NA into such a resonator leads to an inhomogeneous field distribution. By comparing the excitation pattern of a molecule with the calculated vector field distribution, we can determine the position or 3D-orientation of this molecule with high accuracy.