A method of forming a multicore fiber comprises the steps of drilling a plurality of holes in a soot blank, inserting a plurality of graphite rods into the plurality of holes to form a soot preform assembly, consolidating the soot preform assembly in a high temperature furnace to form a glass preform assembly, removing the plurality of graphite rods from the glass preform assembly to form a solid glass preform containing multiple holes, inserting a plurality of glass core canes into the holes to form a multicore preform, placing the multicore preform in a draw furnace, and drawing multicore fiber from the multicore preform.

A method of manufacturing an optical fiber, the method including mounting a glass sleeve in a selective etching apparatus. The sleeve comprising one or more axial through-holes, and the etching apparatus comprising a first end cap with a central aperture disposed therethrough, the first end cap being attached to a first surface of the sleeve. The method further including exposing the sleeve to an acid solution such that a first portion of the first surface is exposed to the acid solution and a second portion of the first surface is not exposed to the acid solution. The first portion being adjacent to the central aperture when the sleeve is mounted in the selective etching apparatus, and the second portion being covered by the first end cap when the sleeve is mounted in the selective etching apparatus.

A preform for multicore optical fiber is described. The preform includes an assembly of core canes arranged in a desired configuration. The core canes are placed in mutual contact with each other to define a series of contact zones between contacting pairs of core canes. The core canes are fused at selected locations within the contact zones to secure the core canes to form a preform from which a multicore optical fiber can be formed. The preform maintains good alignment of core canes and minimizes deformation of core canes during the fiber draw process. Multicore fibers having excellent uniformity in core diameter are produced from the preforms in conventional fiber draw processes.

A multi-core optical fiber preform includes: a rod-shaped main cladding body having one or more main inner holes; main core rods inserted into the one or more main inner holes; and a tip continuously-installed portion disposed at one end of the rod-shaped main cladding body and including a glass rod having no core rod or having one core rod.

A process for manufacturing a MCF preform having core rods positioned in core holes and a common cladding covering each of the core rods. A cylinder is provided having an outside diameter of at least about 200 mm which will form the cladding and may have a center core hole. Peripheral core holes are created in the cylinder. Each of a plurality of core rods is inserted into a respective peripheral core hole. The cylinder with the core rods inserted is heated, thereby collapsing the cylinder onto the core rods and forming the preform. A gap between the peripheral core rods and the peripheral holes is maintained during the step of creating the plurality of peripheral core holes in the range of about 0.2 to 4 mm, an average radial temperature gradient is maintained during the step of heating the cylinder between about 0.5 to 4 K/mm, or both.

A multicore optical fiber of an embodiment has a structure for simultaneously realizing low transmission loss, low fusion splicing loss, and low inter-core crosstalk. The multicore optical fiber includes a plurality of cores comprised of silica glass, a common cladding comprised of silica glass and surrounding the plurality of cores, and a resin coating surrounding the common cladding. The common cladding has a refractive index lower than a refractive index of the plurality of cores. Each of the plurality of cores contains chlorine at 10000 ppm or more in at least part thereof.

A method of making a multicore optical fiber prefom, the method including heating a sleeve blank above its softening temperature and molding the heated sleeve blank within a mold to form a sleeve so that exterior surfaces of the sleeve assume the shape of the mold, the sleeve being formed of silica-based glass and the sleeve comprising a plurality of core cane holes extending within the sleeve. The method further including inserting a core cane through each of the core cane holes, the core canes being formed of silica-based glass and the core canes each comprising a core region.

A preform manufactured by a method which includes removing a part-tube segment from a center of a receiving tube so that the receiving tube has a core rod receiving cut-out which is formed as a remaining annular sector with two opposite edges, axially introducing a central filling rod into the receiving tube so that the receiving tube contains the central filling rod, inserting a core rod in a radial direction from outside into the core rod receiving cut-out between the two opposite edges of the remaining annular sector so that the receiving tube contains the first core rod, axially introducing the receiving tube containing the core rod and the central filling rod into a jacketing tube so as to obtain a jacketing tube containing the receiving tube, and fusing the jacketing tube containing the receiving tube to form the preform.

This application relates generally to an optical fiber for the delivery of infrared light where the polarization state of the light entering the fiber is preserved upon exiting the fiber and the related methods for making thereof. The optical fiber has a wavelength between about 0.9 m and 15 m, comprises at least one infrared-transmitting glass, and has a polarization-maintaining (PM) transverse cross-sectional structure. The infrared-transmitting, polarization-maintaining (IR-PM) optical fiber has a birefringence greater than 10.sup.5 and has applications in dual-use technologies including laser power delivery, sensing and imaging.