Photonic crystal fiber and high-power light transmission system

A photonic crystal fiber having a plurality of holes arranged in the photonic crystal fiber along a longitudinal direction,

• wherein, in a cross section, a hole ratio which is an area of the holes per unit area is larger in a central side than in an outer side in a portion corresponding to a cladding,
• an interval among all of the holes is Λ, and a diameter d1 of the holes in the central side is larger than a diameter d of the holes in the outer side, and, when Λ is represented in a horizontal axis and d1/d is represented in a vertical axis, Λ, d1, and d are in a region where respective regions represented by mathematical formulas C1 overlap, and
• wherein the photonic crystal fiber propagates light of 90 kW·m or more, has an effective cross-sectional area of 500 pmt or more, and has a bending loss of a basic mode of 1 dB/km with a bending radius of 500 mm or less for a wavelength range of 1.05 to 1.07 μm.
• [Mathematical Formulas C1]
• d1/d≤0.633Λ−5.467 (Λ≤11.8 μm)
• d1/d≤−0.0429Λ+2.486 (11.8 μm≤Λ≤15.4 μm)
• d1/d≤0.0454Λ+1.13 (Λ≥15.4 μm)
• d1/d≥1 (Λ≤16.8 μm)
• d1/d≥0.117Λ−0.96 (Λ≥16.8 μm) (C1)