Photons confined in 3D-microcavities doped with quantum dots

Abstract

Summary form only given. We present the concept of a hollow microsphere to realize an efficient coupling between 3D-confined cavity modes and quantized electronic states of semiconductor quantum dots. We demonstrate both experimentally and theoretically that photons emitted from semiconductor nanocrystals placed inside a thin surface shell of a high-quality spherical microcavity efficiently couple to distinct, spectrally well separated high-Q whispering gallery modes (WGM) while cavity modes of higher radial quantum numbers n>1 are suppressed. The observed cavity modes are in the red-orange spectral range and exhibit a cavity finesse Q up to 4000 at T=300 K (Q is defined here as the ratio between resonance energy and linewidth of a cavity mode). The electrodynamic coupling of a radiative dipole to the WGM mode of a dielectric sphere has been investigated as a function of position and orientation of the dipole within the sphere by using the multiple multipole theory.