Polarization-maintaining optical waveguide and absolutely - individual polarization optical waveguide

摘要

A polarization preserving optical fiber and an absolute single polarization optical fiber capable of transmission over a long distance with the polarization condition of a signal light kept preserved. The polarization preserving optical fiber comprises a core unit (11), a photonic crystal structure clad (12) and a jacket unit (13). The photonic crystal structure clad (12) is divided into four divided portions (12a, 12b, 12c, 12d) divided by broken lines extending from the center toward the outer periphery. The diameter (d2) of lattice holes (14a, 14c) in the vicinity of the core unit (11) out of a plurality of lattice holes provided by a pair of divided portions (12a) and (12c) facing each other across the core unit (11) is larger than the diameter (d1) of a lattice holes provided by the other pair of facing divided portions (12b, 12d) and larger than a lattice interval (Λ).