Optical waveguide cores having refractive index profiles that vary angularly about a propagation axis of the core can provide single-mode operation with larger core diameters than conventional waveguides. In one representative embodiment, an optical waveguide comprises a core that extends along a propagation axis and has a refractive index profile that varies angularly about the propagation axis. The optical waveguide can also comprise a cladding disposed about the core and extending along the propagation axis. The refractive index profile of the core can vary angularly along a length of the propagation axis.

Methods for modifying multi-mode optical fiber manufacturing processes are disclosed. In one embodiment, a method for modifying a process for manufacturing multi-mode optical fiber includes measuring at least one characteristic of a multi-mode optical fiber. The at least one characteristic is a modal bandwidth or a differential mode delay at one or more wavelengths. The method further includes determining a measured peak wavelength of the multi-mode optical fiber based on the measured characteristic, determining a difference between the target peak wavelength and the measured peak wavelength, and modifying the process for manufacturing multi-mode optical fiber based on the difference between the target peak wavelength and the measured peak wavelength.

A method of manufacturing a multimode optical fiber includes specifying a peak wavelength λ.sub.P for the multimode optical fiber. The peak wavelength λ.sub.P corresponds to a wavelength at which the multimode optical fiber has a maximum bandwidth. The multimode optical fiber comprises a core and a cladding surrounding and directly adjacent to the core. The core has a radius r.sub.1 and a maximum relative refractive index Δ.sub.1,MAX>0. The cladding comprises a depressed-index region having a minimum relative refractive index Δ.sub.3,MIN<0 and a volume v. A draw tension T for the multimode optical fiber is selected based on a correlation relating peak wavelength λ.sub.P to draw tension T, the correlation comprising a correlation constant. The correlation constant K is a function of at least one of Δ.sub.1,MAX, r.sub.1, v, Δ.sub.3,MIN, and λ.sub.P. The multimode optical fiber is drawn from a preform at the draw tension T.

An optical fiber manufacturing method includes: a drawing step of heating one end portion of an optical fiber preform to melt and deform the one end portion and drawing an optical fiber, wherein in the drawing step, drawing is performed while applying pressure to a melted-deformed portion that is melted and deformed.

A method of manufacturing a tuned optical fiber includes providing a first preform from a set of like preforms each having substantially the same refractive index profile, including amount of axial variation relative to a target refractive index profile. The method includes drawing a reference optical fiber from the first preform and measuring a variation in an optical or physical property as a function of axial position. The method also includes drawing from a second preform from the set of like preforms the tuned optical fiber. The drawing includes using a time-varying tension that reduces the amount of variation of the optical or physical property of interest. The time-varying tension is defined by an amount of axial stress imparted to the tuned fiber needed to alter the refractive index profile and the at least one optical or physical property based on a stress-optic effect.

An optical fiber manufacturing method includes a first process of passing a glass fiber through a fiber path. The fiber path is formed through a cooling tube that is housed in a first casing. The method also includes a second process of leading the glass fiber into a second casing before leading into the first casing. The first process includes supplying a first dry gas, having a dew point lower than the temperature of the cooling tube, into a first dry space formed between the first casing and the cooling tube. The second process includes supplying a second dry gas into a second dry space formed inside the second casing so as to cause air pressure in the second dry space to be higher than air pressure in an external space. The dew point of the second dry gas is lower than the dew point in the external space.

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.

Provided is a system for and a method of processing an optical fiber, such as tapering an optical fiber. The method includes receiving fiber parameters defining characteristics of an optical fiber, modeling an idealized fiber based on the fiber parameters to establish modeled data, and establishing processing parameters. A processing operation is performed on the optical fiber according to the processing parameters to produce a resultant fiber. Aspects of the resultant fiber are measured to establish measured data. The measured data and the modeled data are normalized to a common axis and a difference between the two is determined. The processing parameters are adjusted based on the differences.

An optical fiber forming apparatus comprises: a draw furnace; a tube that extends into the passageway of the draw furnace; and a cooling device at an outlet of the tube, the cooling device comprising: one or more bodies having a top surface and an opposing bottom surface, an opening within the body extending from the top surface through the body to the bottom surface, wherein the opening is configured to pass an optical fiber through the body, and one or more gas outlets within the body configured to direct gas to contact the optical fiber as it passes through the opening.

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.