A method of forming an imaging fibre apparatus comprises arranging rods to form a plurality of stacks each comprising a respective plurality of rods, wherein: for each stack, the respective plurality of rods comprises rods having different core sizes, the rods of different core sizes being arranged in a selected arrangement, and the rods of different core sizes being arranged such that each stack has a respective selected shape; wherein the selected shape or shapes are such that the stacks stack together in a desired arrangement; the method further comprising: drawing each of the plurality of stacks; stacking together the plurality of drawn stacks together in the desired arrangement to form a further stack; drawing the further stack; and using the drawn further stack to form an imaging fibre apparatus, wherein the selected arrangement of the rods in each stack and the selected shape or shapes of the stacks are such that the further stack comprises a repeating pattern of rods of different core sizes.

A method of manufacturing a multicore fiber includes: an initial-preform forming process of forming an initial preform by arranging in an array a plurality of core rods each including a core portion and a cladding portion formed around outer periphery of the core portion; and an optical fiber manufacturing process of manufacturing an optical fiber from the initial preform. Further, the core rods include a plurality of holes, and the core rods are arranged in a manner that one hole is arranged between two core portion adjacent to each other in the initial-preform forming process.

A fiber optic imaging element includes medium-expansion and a fabrication method including: (1) matching a core glass rod with a cladding glass tube to perform mono fiber drawing; (2) arranging the mono fibers into a mono fiber bundle rod, and then drawing the mono fiber bundle rod into a multi fiber; (3) arranging the multi fiber into a multi fiber bundle rod, and then drawing the multi fiber bundle rod into a multi-multi fiber; (4) cutting the multi-multi fiber, and then arranging the multi-multi fiber into a fiber assembly buddle, then putting the fiber assembly buddle into a mold of heat press fusion process, and performing the heat press fusion process to prepare a block of the fiber optic imaging element with medium-expansion; and (5) edged rounding, cutting and slicing,

A multi-core fiber includes: a plurality of cores; and a cladding portion formed around outer peripheries of the cores. Further, the cores each have a propagation characteristic conforming to any one of a plurality of standards for optical propagation characteristics, and of the cores, cores that are closest to each other conform to standards different from each other.

A multi-fiber light guide includes: light guiding fibers, each fiber including an elongated glass core; a glass cladding, the cores being surrounded by the cladding to form a rigid and continuous glass element, the cores having a higher refractive index than the cladding such that light can be guided by a total reflection along the cores, which end in two abutting faces of the glass element such that light can be guided along the cores from one abutting face to the other abutting face; and an ion exchange layer at each of the abutting faces, the glass of the cores and the glass of the cladding including alkali ions, which are at least partly exchanged by alkali ions of a higher atomic number within the ion exchange layer at the abutting faces, the exchanged alkali ions within the ion exchange layer imparting a compressive stress at the abutting faces.

According to embodiments, a method of making a microstructured glass article includes bundling M bare optical fibers in a fiber bundle, wherein M is an integer greater than 100. Thereafter, the fiber bundle may be inserted in a cavity of a soot preform. The soot preform may have a density of less than or equal to 1.5 g/cm.sup.3 and comprise silica-based glass soot. The soot preform and inserted fiber bundle may then be consolidated to form a microstructured glass article preform. The microstructured glass article preform may then be drawn into the microstructured glass article comprising M core elements embedded in a cladding matrix.

An optical fiber rod (30) according to the present invention includes a center region (35), an outer region (31) formed around the center region (35), and an intermediate region (33) formed between the center region (35) and the outer region (31), and satisfies nA>nB>nC where nA is the refractive index of a material A produced by polymerization of a monomer ma, nB is the refractive index of a material B produced by polymerization of a monomer mb, and nC is the refractive index of a material C produced by polymerization of a monomer mc. The center region (35) is made of a material produced by polymerization of a monomer mixture containing the monomer ma, the outer region (31) is made of a material produced by polymerization of a monomer mixture containing the monomer mc, and the intermediate region (33) is made of a material produced by polymerization of a monomer mixture containing the monomer mb. The refractive index decreases in the order: the center region (35)>the intermediate region (33)>the outer region (31).

A method for adjusting an etchability of a first borosilicate glass by heating the first borosilicate glass; combining the first borosilicate glass with a second borosilicate glass to form a composite; and etching the composite with an etchant. A material having a protrusive phase and a recessive phase, where the protrusive phase protrudes from the recessive phase to form a plurality of nanoscale surface features, and where the protrusive phase and the recessive phase have the same composition.

A preform (10) for an antiresonant hollow core optical fibre comprises an outer jacket tube (12) having an inner surface and a central longitudinal axis (24); a plurality of antiresonant cladding tubes (14) spaced apart at predefined peripheral locations around the inner surface of the outer jacket tube (12), each antiresonant cladding tube (14) in contact with the inner surface such that a central longitudinal axis (26) of each antiresonant cladding tube (14) is at a first radial distance from the central longitudinal axis (24) of the outer jacket tube (12); and a plurality of spacing elements (22) disposed alternately with the antiresonant cladding tubes (14) and each in contact with an outer surface of each of two adjacent antiresonant cladding tubes (14) at one or more contact points (28), the contact points (28) at a second radial distance from the central longitudinal axis (24) of the outer jacket tube (12), the second radial distance being greater than the first radial distance.

A fiber optic imaging element includes medium-expansion and a fabrication method including: (1) matching a core glass rod with a cladding glass tube to perform mono fiber drawing; (2) arranging the mono fibers into a mono fiber bundle rod, and then drawing the mono fiber bundle rod into a multi fiber; (3) arranging the multi fiber into a multi fiber bundle rod, and then drawing the multi fiber bundle rod into a multi-multi fiber; (4) cutting the multi-multi fiber, and then arranging the multi-multi fiber into a fiber assembly buddle, then putting the fiber assembly buddle into a mold of heat press fusion process, and performing the heat press fusion process to prepare a block of the fiber optic imaging element with medium-expansion; and (5) edged rounding, cutting and slicing, face grinding and polishing the prepared medium-expansion block into a billet.