Patent ID: 8035891

Claim:
A photonic bandgap fiber comprising: a core, a cladding that surrounds the core, and a plurality of high refractive index portions disposed within the cladding; wherein the plurality of high refractive index portions has a refractive index higher than a refractive index of the cladding and are provided in the cladding forming a triangular lattice structure with a lattice constant Λ, wherein a refractive index of the core is higher than the refractive index of the cladding and lower than the refractive index of the plurality of high refractive index portions, and wherein a coupling length between the core and a plurality of high refractive index portions that is closest to the core is longer than a coupling length between adjacent high refractive index portions, for wavelengths of light for which the propagation of light in the core is suppressed.