  We study the effects of disorder on the coupling strength of coupled photonic
crystal slab cavities by considering fully-3D electromagnetic calculations.
Specifically, we investigate two coupled L3 cavities at 30{\deg} and 60{\deg}
configurations, where the coupling strength J (or photon hopping) is extracted
from the simulations in the presence of disorder. We found that the relative
fluctuations of the photon hopping are more sensitive to disorder effects than
the corresponding fluctuations in the eigenfrequencies of the coupled cavities.
Furthermore, for the typical range of disorder in state-of-the-art devices, the
J fluctuations are found to increase linearly as a function of the disorder
amplitude. This allows to set upper bounds to the amplitude of fabrication
imperfections, for which the coupling predicted by design can still be
expected, on average, in a fabricated device.
