Patent ID: 7831121

Claim:
An extended triangular lattice type photonic bandgap fiber, comprising: a cladding and, a capillary core, wherein the cladding comprises a plurality of holes disposed within a silica glass portion in a longitudinal direction of the fiber and arranged in an extended triangular lattice shape, wherein each of the plurality of holes has a hexagonal cross-section and a thickness of walls interposed between the plurality of holes is w b ; the capillary core comprises a plurality of holes arranged in a triangular lattice shape, wherein each of the plurality of holes has a hexagonal cross-section and a thickness of walls interposed between the plurality of holes is w c ; wherein the holes in the capillary core have a smaller cross sectional area than the holes in the cladding; wherein the holes in the cladding and in the core extend in the direction of propagation of light in the capillary core; and wherein w b <w c .