We found that self-determining collimated light is generated in a photonic crystal fabricated
on silicon. The divergence of the collimated beam is insensitive to that of the incident beam
and much smaller than the divergence that would be generated in conventional Gaussian
optics. The incident-angle dependence of the self-collimated light propagation including
lens-like divergent propagation was interpreted in terms of the highly modulated dispersion
surfaces with inflection points, where the curvature changes from downward to upward …