Optical fiber preform, method for measuring refractive index profile of optical fiber preform, and method for producing optical fiber preform
AssigneeFujikura Ltd.
InventorJunichi Takahashi
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Abstract
An optical fiber preform having a refractive index profile includes a fluctuation region in which a fluctuation of a refractive index is repeated. The fluctuation consists of an increase in the refractive index and a decrease in the refractive index. At least a part of the fluctuation region is in an outer region at a distance of equal to or greater than 7 mm from a center of the optical fiber preform. A width of the fluctuation in a radial direction of the optical fiber preform is less than 2 μm in the outer region.
Claims10
1-9. (canceled)
An optical fiber preform having a refractive index profile, the optical fiber preform comprising:
- a fluctuation region in which a fluctuation of a refractive index is repeated, wherein
- the fluctuation consists of an increase in the refractive index and a decrease in the refractive index,
- at least a part of the fluctuation region is in an outer region at a distance of equal to or greater than 7 mm from a center of the optical fiber preform, and
- a width of the fluctuation in a radial direction of the optical fiber preform is less than 2 μm in the outer region.
A method for producing an optical fiber preform, the method comprising:
- forming a rod-shaped glass member having a refractive index profile, the forming of the rod-shaped glass member comprising:
- forming a porous glass body by depositing glass fine particles in layers on a glass rod rotating around an axis;
- and
- sintering the porous glass body, wherein
- the rod-shaped glass member includes a fluctuation region in which a fluctuation of a refractive index is repeated,
- the fluctuation consists of an increase in the refractive index and a decrease in the refractive index;
- and
- stretching the rod-shaped glass member, wherein
- a rotational speed of the glass rod and a stretch ratio of the rod-shaped glass member are set such that:
- at least a part of the fluctuation region of the stretched rod-shaped glass member is in an outer region at a distance of equal to or greater than 7 mm from a center of the stretched rod-shaped glass member, and
- a width of the fluctuation in a radial direction of the stretched rod-shaped glass member is less than 2 μm in the outer region.
Dependencies are inferred from the claim text.