POLARIZATION MAINTAINING OPTICAL FIBER AND OPTICAL FIBER FOR ABSOLUTE SINGLE POLARIZATION

摘要

PROBLEM TO BE SOLVED: To provide a polarization maintaining optical fiber and an optical fiber for absolute single polarization which enable long-distance transmission while maintaining the polarization state of signal light. SOLUTION: The polarization maintaining optical fiber is constituted of a core part 11, a photonic crystal structure clad 12, and a jacket part 13. The photonic crystal structure clad 12 is divided into four split parts 12a, 12b, 12c, and 12d divided by broken lines extended from the center to the outer periphery. A diameter d2 of grid holes 14a and 14c in the vicinity of the core part 11 out of a plurality of grid holes which the pair of split parts 12a and 12c facing each other with the core part 11 between them have is made longer than a diameter d1 of grid holes which the other pair of split parts 12b and 12d facing each other have. The diameter d2 which the split parts 12a and 12c have is made longer than a grid intervalΛ.