Patent ID: 7292762

Claim:
A hole-assisted holey fiber, comprising: a core region; a cladding region provided around the core region; and a plurality of holes that are provided in the cladding region around the core region, wherein a refractive index of the core region is higher than that of the cladding region, the plurality of holes form two layers comprising an inner hole layer and an outer hole layer, the inner hole layer has the same number of holes as the number of the holes in the outer hole layer, the holes of the outer hole layer are provided in locations in which holes of the inner hole layer are absent when viewed from the center of the core region, holes of the outer hole layer have equal diameters and holes of the inner hole layer have equal diameters, a distance Λ 1 from a center of the core region to a center of a hole of the inner hole layer and a distance Λ 2 from the center of the core region to a center of a hole of the outer hole layer satisfy Λ 1 <Λ 2 , and a diameter d 1 of a hole of the inner hole layer and a diameter d 2 of a hole of the outer layer satisfy d 1 ≦d 2 .