| In recent years there has been increasing interest in embedding nanocrystal quantum dots into microcavities, whether to get Purcell-enhanced emission, or to reach the lasing threshold. For these purposes spherical resonators have the outstanding ability to confine light in three dimensions with comparatively high quality factors Q. However, the incoupling of excitation into such structures, including a selective excitation of different regions, is often a problem. We report on a newly developed technique, the hydrophobic spreading, to prepare hemispherical resonators with different diameters on a distributed Bragg reflector. The planar, and for excitation wavelength transparent DBR-side allows a selectively excitation, making this type of cavity a favourable new resonator. By embedding semiconductor nanocrystal quantum dots, we achieve a highly efficient incoupling of their emission into Whispering-Gallery modes. The occurring modes are described with a two-dimensional model and assigned to the experimental data. |
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