US Patent 7593611 Photonic band gap fiber and method of producing the same

A photonic band gap fiber is provided having multiple air holes in a silica portion extending in the longitudinal direction of the fiber. The fiber includes a cladding containing an air hole periodic structure in an extended triangular lattice configuration, wherein first rows each having a number of air holes at a first pitch are arranged alternately in the cross section of the fiber with multiple second rows of air holes each with multiple air holes at a second pitch which is twice the first pitch. The fiber further includes an air hole core.