Hemispherical resonators with embedded nanocrystal quantum rod emitters

We report a technique to prepare hemispherical resonators on a distributed Bragg reflector (DBR). This so-called hydrophobic spreading allows the creation of hemispherical structures with diameters ranging from 5 to 50 μm. By embedding semiconductor nanocrystal quantum rods (NQRs) into these structures, we achieve a coupling of their emission into whispering-gallery modes. Although the NQR-emission is confined in three dimensions, the DBR is transparent for the excitation, allowing selective excitation of different regions of the hemisphere. Employing a two-dimensional model to approximately describe relevant modes, we are able to estimate the refractive index and diameters of the hemispheres from spectral data.