“…Since the effective index of the holey cladding depends on the air hole arrangement and the wavelength, PCFs bring unique properties not seen in conventional optical fibers. [1][2][3][4] Hence, PCFs have been applied as functional fibers, for example, for dispersion control, 5,6) supercontinuum generation, [7][8][9] wavelength conversion, [9][10][11] and so on. Since low-loss PCFs were developed, 12,13) PCFs have been expected as transmission lines in fiber optic communication systems.…”