Patent ID: 9075185
Filing Date: 2015-07-07
Classification: G02B

Abstract:
1. A hole-assisted optical fiber comprising: a core portion; and a cladding portion that includes an inner cladding layer formed around an outer periphery of the core portion and having a refractive index lower than that of the core portion, an outer cladding layer formed around an outer periphery of the inner cladding layer and having a refractive index higher than that of the inner cladding layer and lower than that of the core portion, and a plurality of holes formed around the core portion, wherein a diameter of the core portion is in a range of 3 μm to 9.8 μm, a relative refractive index difference of the core portion relative to the outer cladding layer is in a range of 0.11% to 0.45%, an outside diameter of the inner cladding layer is equal to or less than 53 μm, a relative refractive index difference of the inner cladding layer relative to the outer cladding layer is a negative value equal to or more than −0.30%, a diameter of each of the plurality of holes is in a range of 2.4 μm to 4.0 μm, a hole occupancy rate is in a range of 17% to 48%, a bending loss at a wavelength of 1625 nm when bent at a radius of 5 mm is equal to or less than 1 dB/turn, and a cut-off wavelength is equal to or less than 1550 nm, and the hole occupancy rate S (%) is defined by the following expression (1): where N is the number of the plurality of holes, d (μm) is the diameter of each of the plurality of holes, and R (μm) is a radius of an inscribed circle which is brought into internal contact with each of the plurality of holes.