Abstract: Provided is an extreme bending insensitive optical fiber. The optical fiber includes a core comprising a maximum refractive index difference ?n1 in the optical fiber, an inner layer comprising a refractive index difference ?n2 that is smaller than the maximum refractive index of the core and decreases in a direction away from the core, the inner layer being positioned outside the core, and a trench layer comprising an inner-circumference refractive index difference ?n3 that is smaller than the refractive index difference of the inner layer and an outer-circumference refractive index difference ?n4 that is a minimum refractive index difference in the optical fiber.

Abstract: Provided is an extreme bending insensitive optical fiber. The optical fiber includes a core comprising a maximum refractive index difference ?n1 in the optical fiber, an inner layer comprising a refractive index difference ?n2 that is smaller than the maximum refractive index of the core and decreases in a direction away from the core, the inner layer being positioned outside the core, and a trench layer comprising an inner-circumference refractive index difference ?n3 that is smaller than the refractive index difference of the inner layer and an outer-circumference refractive index difference ?n4 that is a minimum refractive index difference in the optical fiber.

Abstract: Disclosed are a method for fabricating an optical fiber preform and a method for fabricating an optical fiber using the optical fiber preform. The method for fabricating the optical fiber preform including the steps of: (a) growing a first soot preform on a starting member by a soot deposition; (b) dehydrating the first soot preform; (c) sintering the first dehydrated soot preform to obtain a first glassed optical fiber perform; (e) growing an over-clad soot layer on the first optical fiber preform by soot deposition to obtain a second soot preform; and (f) sintering the second soot preform so as to obtain a second optical fiber preform which is glassed, wherein an average density of the first soot preform is substantially within a range of 0.19˜0.30 g/cc, and the average density of the over-clad soot layer is substantially within a range of 0.5˜0.75 g/cc.

Abstract: Disclosed is an apparatus for fabricating an optical fiber preform through an external vapor deposition process. The apparatus includes a lathe on which a primary preform is rotatably mounted by chucks, a burner assembly including a burner installation block having an inclined surface and a plurality of burners installed on the inclined surface of the burner installation block in such a manner that the burners spray flames and source gas towards the primary preform with mutually different spraying angles, and a carrier unit for moving the burner assembly lengthwise along the primary preform.