We report angle and polarization resolved reflectivity from stronglyphotonic fcc crystals consisting of air spheres in titania. For a 30range of angles of incidence, multiple peaks with distinct polarizationdependence are observed that clearly reveal avoided crossing behavior.Calculated photonic dispersion curves show that the multiple peaksresult from band repulsion of Bloch states due to simultaneous Braggdiffraction by (111) and (200) planes. Our results demonstrate thatmany-wave coupling leads to substantial deviations from simple Braggdiffraction, with significantly flattened bands, a requirement for theappearance of complete photonic band gaps.

H. M. van Driel and W. L. Vos

2000

10/2000

Phys. Rev. B

62

9872-9875