Methods for classifying a core cane of an multimode optical fiber are disclosed. In embodiments, the method includes determining a relative refractive index profile Δ(r) of the core cane; fitting the relative refractive index profile Δ(r) to an alpha profile Δ.sub.fit(r) defined by:

[00001]${\Delta }_{\mathrm{fit}}\left(r\right)={\Delta }_{o,\mathrm{fit}}\left(1-{\left(\frac{r}{a_{\mathrm{fit}}}\right)}^{{\alpha }_{\mathrm{fit}}}\right)$

where Δ.sub.o,fit is a relative refractive index at a longitudinal centerline of the core cane, α.sub.fit is a core shape parameter, and a.sub.fit is an outer radius of the core cane; generating a non-alpha residual profile Δ.sub.diff(r)=Δ(r)−Δ.sub.fit(r) for the core cane; computing one or more metrics from Δ.sub.diff(r), and using the one or metrics in a classification of the core cane, the classification comprising a prediction of whether a bandwidth at a pre-determined wavelength of an optical fiber drawn from a preform comprising the core cane exceeds a pre-determined bandwidth at the pre-determined wavelength.

A new type of all-silica optical fiber is described; a Structured Silica Clad Silica (SSCS) optical fiber, whose cladding is structured to provide mode mixing within the core; and/or to have an average effective refractive index. Its cross-section is essentially symmetrical, it can be used, among other objects, to provide flatter, more speckle-free outputs from fiber lasers, or other limited mode photonic sources. Building the new fiber structure around a rare earth doped laser core provides a better fiber laser/amplifier for cladding pumping. The structured silica cladding contains paired layers, in which a down doped silica layer is followed by a layer of pure, or lesser down-doped, or even up-dope silica, and die number of paired layers is, typically, from 5 to about 25, and, generally, within the paired layers the ratio of thickness of the higher RI layer of silicate the down-doped silica is very broad, lying between about 0.0625 to about 16, depending on the intended use of the SSCS fibers. In some versions, the main core material can be up-doped silica with pure silica or down-doped silica as the primary second component.

A new type of all-silica optical fiber is described; a Structured Silica Clad Silica (SSCS) optical fiber, whose cladding is structured to provide mode mixing within the core; and/or to have an average effective refractive index. Its cross-section is essentially symmetrical, it can be used, among other objects, to provide flatter, more speckle-free outputs from fiber lasers, or other limited mode photonic sources. Building the new fiber structure around a rare earth doped laser core provides a better fiber laser/amplifier for cladding pumping. The structured silica cladding contains paired layers, in which a down doped silica layer is followed by a layer of pure, or lesser down-doped, or even up-dope silica, and die number of paired layers is, typically, from 5 to about 25, and, generally, within the paired layers the ratio of thickness of the higher RI layer of silicate the down-doped silica is very broad, lying between about 0.0625 to about 16, depending on the intended use of the SSCS fibers. In some versions, the main core material can be up-doped silica with pure silica or down-doped silica as the primary second component.

A method of manufacturing optical fiber in an optical fiber production system is provided. The method includes the providing a draw furnace operatively coupled to a slow cooling device along a draw pathway, drawing the optical fiber from an optical fiber preform in the draw furnace and along the draw pathway, heat treating the optical fiber in the slow cooling device positioned along the draw pathway, the slow cooling device comprising an inlet, an outlet, and a process tube extending between the inlet and the outlet, and selecting an opening size of an outlet nozzle operatively coupled to the outlet based on a draw speed of the optical fiber.

A method of processing an optical fiber that includes drawing an optical fiber along a fiber pathway through a hollow light pipe, wherein the hollow light pipe comprises a first end having an opening with a radius R.sub.p, a second end and a pipe body comprising a chamber extending from the first to the second end, the fiber pathway extending through the pipe body, and a reflective coating is disposed on the pipe body, and directing a light from a directed light source into the hollow light pipe through the opening such that the light is reflected by the reflective coating while propagating in the hollow light pipe, the optical fiber absorbing the light reflected by the reflective coating, wherein the light enters the opening of the hollow light pipe at an input angle in a range of from 10° to 70° with respect to the fiber pathway.

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-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.

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.

A method for manufacturing of an optical fibre preform (100) using optimized core particles includes optimization of particles of calcium aluminum silicate powder (104), utilizing the optimized core particles, sintering the optimized core particles inside a fluorine doped glass tube (106) and drawing of an optical fibre. Particularly, the optimization of the particles of calcium aluminum silicate powder (104) facilitates formation of the optimized core particles and the optimized core particles are filled inside the fluorine doped glass tube (106). Moreover, sintering of the optimized core particles solidifies and adheres smoothly with the fluorine doped glass tube (106) for manufacturing of the optical fibre preform (100).