Patent ID: 11880064
Assignee: FURUKAWA ELECTRIC CO., LTD.
Field: Optics (Instruments)
Classification: CPC G  C | IPC C  G

Claim 0:
1. An optical fiber comprising:
a core made of silica based glass;
a cladding made of silica based glass and configured to cover an outer periphery of the core, the cladding having a refractive index that is lower than a maximum refractive index of the core; and
a coating configured to cover an outer periphery of the cladding, the coating including
a primary coating layer located on the cladding side, and
a secondary coating layer located on an outer peripheral side of the primary coating layer, wherein

the core includes a central core portion and a depressed layer that is formed an outer periphery of the central core portion,
the optical fiber has a W-type refractive index profile,
a relative refractive-index difference Δ1 of the central core portion with respect to the cladding is larger than or equal to 0.33% and smaller than or equal to 0.40%,
a relative refractive-index difference Δ2 of the depressed layer with respect to the cladding is larger than or equal to −0.20% and less than 0%,
when a core diameter of the central core portion is 2a, and an outer diameter of the depressed layer is 2b, b/a is smaller than or equal to 5,
an outer diameter of the cladding is less than 100 μm,
a thickness of the primary coating layer is larger than or equal to 15 m,
a mode field diameter at a wavelength of 1310 nm is larger than or equal to 8.6 μm and smaller than or equal to 9.2 μm,
an effective cutoff wavelength is smaller than or equal to 1260 μm, and
a bending loss at a wavelength of 1550 rim when bending is made at a diameter of 60 mm is smaller than or equal to 0.1 dB/100 turn.