  We study the coupling of cavities defined by the local modulation of the
waveguide width using confocal photoluminescence microscopy. We are able to
spatially map the profile of the antisymmetric (antibonding) and symmetric
(bonding) modes of a pair of strongly coupled cavities(photonic molecule) and
follow the coupled cavity system from the strong coupling to the weak coupling
regime in the presence of structural disorder. The effect of disorder on this
photonic molecule is also investigated numerically with a finite-difference
time-domain method and a semi-analytical approach, which enables us to quantify
the light localization observed in either cavity as a function of detuning.
