  Rotation-induced splitting of the otherwise degenerate photonic bands is
predicted for a two-dimensional photonic crystal made of evanescently coupled
microcavities. The symmetry-broken energy splitting is similar to the Zeeman
splitting of atomic levels or electron's (hole's) magnetic moment sublevels in
an external magnetic field. The orbital motion of photons in periodic photonic
lattice of microcavities is shown to enhance significantly such Coriolis-Zeeman
splitting as compared to a solitary microcavity [D.L. Boiko, Optics Express 2,
397 (1998)]. The equation of motion suggests that nonstationary rotation
induces quantum transitions between photonic states and, furthermore, that such
transitions will serve as a source of nonstationary gravitational field.
