A horizontal lathe for manufacturing a porous optical fiber preform, the horizontal lathe being configured to hold and fix two opposite ends of a target in such a manner that a longitudinal direction of the target is a substantially horizontal direction, and cause the target to be rotated around an axis parallel to the longitudinal direction thereof as a rotation axis. The horizontal lathe includes a thermal expansion absorbing mechanism configured to absorb a change in dimension of the target, the change being due to thermal expansion of the target in a direction of the rotation axis.

A horizontal lathe for manufacturing a porous optical fiber preform, the horizontal lathe being configured to hold and fix two opposite ends of a target in such a manner that a longitudinal direction of the target is a substantially horizontal direction, and cause the target to be rotated around an axis parallel to the longitudinal direction thereof as a rotation axis. The horizontal lathe includes a thermal expansion absorbing mechanism configured to absorb a change in dimension of the target, the change being due to thermal expansion of the target in a direction of the rotation axis.

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.

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 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 method of forming an optical element is provided. The method includes producing silica-based soot particles using chemical vapor deposition, the silica-based soot particles having an average particle size of between about 0.05 μm and about 0.25 μm. The method also includes forming a soot compact from the silica-based soot particles and doping the soot compact with a halogen in a closed system by contacting the silica-based soot compact with a halogencontaining gas in the closed system at a temperature of less than about 1200° C.

A device for manufacturing an optical preform by means of an internal vapour deposition process including an energy source, a hollow substrate tube having a supply side and a discharge side and the energy source being moveable along a length of the hollow substrate tube, and an elongation tube connected to the hollow substrate tube at the discharge side thereof, wherein the hollow substrate tube extends into an interior of the elongation tube and an internal diameter of the elongation tube is at least 0.5 millimeters larger than an external diameter of the hollow substrate tube.

A device for manufacturing an optical preform by means of an internal vapour deposition process including an energy source, a hollow substrate tube having a supply side and a discharge side and the energy source being moveable along a length of the hollow substrate tube, and an elongation tube connected to the hollow substrate tube at the discharge side thereof, wherein the hollow substrate tube extends into an interior of the elongation tube and an internal diameter of the elongation tube is at least 0.5 millimeters larger than an external diameter of the hollow substrate tube.

The porous glass base material manufacturing apparatus releases gas of organic siloxane raw materials into the flame of a group of burners that moves relative to a starting base material along the longitudinal direction of the starting base material rotating around a rotation axis along the longitudinal direction to form soot of porous glass particles on the surface of the starting base material. The porous glass base material manufacturing apparatus is equipped with a vaporizer that vaporizes liquid raw materials containing organic siloxane in a liquid state supplied from a raw material tank to make a raw material mixed gas mixed with raw material gas and carrier gas and a raw material gas pipe that supplies the raw material mixed gas to the burner. The raw material gas pipe is insulated and kept warm by double insulation.

The porous glass base material manufacturing apparatus releases gas of organic siloxane raw materials into the flame of a group of burners that moves relative to a starting base material along the longitudinal direction of the starting base material rotating around a rotation axis along the longitudinal direction to form soot of porous glass particles on the surface of the starting base material. The porous glass base material manufacturing apparatus is equipped with a vaporizer that vaporizes liquid raw materials containing organic siloxane in a liquid state supplied from a raw material tank to make a raw material mixed gas mixed with raw material gas and carrier gas and a raw material gas pipe that supplies the raw material mixed gas to the burner. The raw material gas pipe is insulated and kept warm by double insulation.