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Q: Fachverband Quantenoptik und Photonik
Q 62: Poster: Quantum Optics and Photonics III
Q 62.49: Poster
Donnerstag, 26. März 2015, 17:00–19:00, C/Foyer
Transverse Mode Coupling and Diffraction Loss in Fibre-Based Microcavities — •Julia Benedikter1,2, Thomas Hümmer1,2, Matthias Mader1,2, Theodor W. Hänsch1,2, and David Hunger1,2 — 1Ludwig-Maximilians-Universität München, Schellingstr. 4, 80799 München — 2Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching
Fibre-based Fabry-Pérot resonators provide very small mode volumes and high finesse in a tuneable and accessible geometry [1, 2]. This makes them attractive for various applications ranging from cold atom and ion experiments to cavity optomechanics and cavity-enhanced single photon sources. In contrast to macroscopic cavities, the mirrors are not spherical, but rather have a nearly Gaussian profile originating from the laser machining process used to shape the fibre surface. We find that non-spherical mirror shape and finite mirror size lead to loss, mode deformation, and frequency shifting at particular mirror separations. For long cavities, diffraction loss limits the useful mirror separation to values below the expected stability range. Using scanning cavity microscopy, we observe spatially localised coupling resonances, owing to a variation of the mirror properties. We attribute these findings to resonant coupling between different transverse modes of the cavity and show that a model based on resonant state expansion [3] taking into account the measured mirror profile can reproduce the measurements.
[1] Hunger et al., NJP 12, 065038 (2010)
[2] Hunger et al., AIP Advances 2, 012119 (2012)
[3] Kleckner et al., PRA 81, 043814 (2010)