The present disclosure provides a method for sintering of an optical fibre preform. The method includes manufacturing of the optical fibre preform. In addition, the method includes drying and sintering of the optical fibre preform. In addition, drying and sintering of the optical fibre preform results into a sintered optical fibre preform. Further, the method includes preparation of a glass rod from the sintered optical fibre preform. Furthermore, the method includes insertion of the glass rod into a centreline hole of the silica soot preform. The centreline hole is created by removing mandrel from the silica soot preform. Moreover, the method includes drying and sintering of the silica soot preform. Also, drying and sintering of the silica soot results into a sintered silica soot preform. Also, the method includes drawing of a rod from the sintered silica soot preform.

The present invention relates to a preform assembly and a method for drawing a multicore optical fibre and a holey fibre. Particularly, the preform assembly includes a hollow cylindrical tube, a plurality of discs stacked inside the hollow cylindrical tube and a plurality of core rods inserted in a plurality of through holes in each of the plurality of discs.

A multicore fiber is provided that includes a plurality of elliptical cores spaced apart from one another. Each of the plurality of elliptical cores has an elliptical shape. The multicore fiber also includes a cladding surrounding the plurality of elliptical cores.

An apparatus for optical fiber manufacturing process is provided, including a raw material providing structure, a dopant providing structure, and a preform forming substrate tube. The dopant providing structure is disposed at a downstream side of the raw material providing structure and in communication with the raw material providing structure. The dopant providing structure includes an outer tube, a first inner tube, a first dopant providing container, a second inner tube, and a second dopant providing container. The first inner tube is disposed in the outer tube. The first dopant providing container is disposed in the first inner tube. The second inner tube is disposed in the outer tube at a downstream of the first inner tube. The second dopant providing container is disposed in the second inner tube. The preform forming substrate tube is disposed at a downstream side of the dopant providing structure.

Multi-core optical fiber ribbons and methods for making multi-core optical fiber ribbons are described herein. In one embodiment, a multi-core optical fiber ribbon includes at least two core members formed from silica-based glass and oriented in parallel with one another in a single plane. Adjacent core members have a center-to-center spacing ≧15 microns and a cross-talk between adjacent core members is ≦−25 dB. In this embodiment each core member is single-moded with an index of refraction n.sub.c, and a core diameter d.sub.c. In an alternative embodiment, each core member is multi-moded and the center-to-center spacing between adjacent core members is ≧25 microns. A single cladding layer is formed from silica-based glass and surrounds and is in direct contact with the core members. The single cladding layer is substantially rectangular in cross section with a thickness ≦400 microns and an index of refraction n.sub.cl<n.sub.c.

The vacuum-based methods of forming an optical fiber preform include applying a vacuum to a preform assembly. The preform assembly has at least one glass cladding section with one or more axial through holes, with one or more canes respectively residing in the one or more axial through holes. The opposite ends of the at least one glass cladding section are capped to define a substantially sealed internal chamber. A vacuum is applied to the substantially sealed internal chamber to define a vacuum-held preform assembly. The methods also include heating the vacuum-held preform assembly to just above the glass softening point to consolidate the vacuum-held preform to form the cane-based glass preform. An optical fiber is formed by drawing the cane-based glass preform. The same furnace used to consolidate the vacuum-held preform can be used to draw the optical fiber.

A multicore fiber according to an embodiment of the present invention includes a plurality of cores and a cladding that encloses the plurality of the cores. The external form of the cladding in a cross section is formed of an arc portion that is formed in an arc shape relative to the center axis of the cladding and a non-arc portion that is pinched between two ends of the arc portion and not formed in an arc shape relative to the center axis of the cladding. The non-arc portion is formed with a pair of projections projecting from two ends of the arc portion on the opposite side of the center axis relative to a straight line connecting the both ends of the arc portion and one or more of recesses pinched between the pair of the projections.

A multicore fiber is provided. The multicore fiber includes a plurality of cores spaced apart from one another, and a cladding surrounding the plurality of cores and defining a substantially rectangular or cross-sectional shape having four corners. Each corner has a radius of curvature of less than 1000 microns. The multicore fiber may be drawn from a preform in a circular draw furnace in which a ratio of a maximum cross-sectional dimension of the preform to an inside diameter of the preform to an inside diameter of the draw furnace is greater than 0.60. The multicore fiber may have maxima reference surface.

The vacuum-based methods of forming an optical fiber preform include applying a vacuum to a preform assembly. The preform assembly has at least one glass cladding section with one or more axial through holes, with one or more canes respectively residing in the one or more axial through holes. The opposite ends of the at least one glass cladding section are capped to define a substantially sealed internal chamber. A vacuum is applied to the substantially sealed internal chamber to define a vacuum-held preform assembly. The methods also include heating the vacuum-held preform assembly to just above the glass softening point to consolidate the vacuum-held preform to form the cane-based glass preform. An optical fiber is formed by drawing the cane-based glass preform. The same furnace used to consolidate the vacuum-held preform can be used to draw the optical fiber.

The MCF of the present disclosure suppresses occurrence of structural abnormality such as air bubbles in the vicinity of a boundary between a marker and a cladding. The MCF includes a glass optical fiber including a plurality of cores, a marker, and a cladding, and a resin coating. On a cross section of the MCF, centers of the plurality of cores and a center of the marker constitute a plane figure having a rotational symmetry of order 1 with respect to a center of the cross section. Moreover, on the cross section, the marker is disposed so as to be located on a circumference of a circle having a center coinciding with the center of the cross section and having the circumference passing through the respective centers of the plurality of cores.