Nanocrystal-doped polymer spheres as building blocks for coupled resonator optical waveguides

Abstract

We investigate the coherent cavity-field coupling in chains of polystyrene microspheres doped with CdSe nanocrystals. The coupled cavity emission is studied by imaging spectroscopy and polarization-sensitive mode mapping. The spatial dependence and polarization nature of coupled and uncoupled cavity states are discussed for applications as building blocks in coupled resonator optical waveguides. When coherent photon states are formed in the coupled cavities, the symmetric field distribution of a single microsphere evolves into a directional emission pattern with strongest modifications along the axes of the coupled cavity system. For weak coherent cavity coupling, the coupled modes show almost vanishing field intensity along the axis. In case of weak coupling still cavity modes can be observed for which the single sphere Q-factor is maintained which is promising for applications in coupled resonator optical waveguides.