Photoluminescence mapping of coupled and detuned states in photonic molecules

We study the coupling of cavities embedded in a photonic crystal waveguide and report the clear signature of a strongly coupled system using photoluminescence microscopy. In particular, we are able to spatially map the profile of the antisymmetric (antibonding) and symmetric (bonding) modes of a pair of coupled cavities (photonic molecule) defined by the local modulation of the waveguide width. The mode localization observed in either cavity due to structural disorder are reproduced numerically by nm shift in the waveguide modulation.