A method of forming an optical fiber preform includes flowing a precursor stream through a burner toward a substrate, the precursor stream comprising a glass precursor gas and a carrier gas, the carrier gas having a kinematic viscosity at 2000 K of greater than 5 cm.sup.2/sec and a ratio of heat capacity to universal gas constant (C.sub.p/R) 2000 K of less than 4; flowing an inflammable gas through the burner; pyrogenically forming glass particles from the glass precursor gas, the pyrogenically forming comprising combusting the inflammable gas; flowing a shield gas through the burner, the shield gas flowing between the precursor stream and the inflammable gas, the shield gas having a kinematic viscosity at 2000 K of greater than 5 cm.sup.2/sec and a ratio of heat capacity to universal gas constant (C.sub.p/R) at 2000 K of less than 4; and depositing the glass particles onto the substrate.

An optical fiber may comprise a core doped with one or more active ions to guide signal light from an input end of the optical fiber to an output end of the optical fiber, a cladding surrounding the core to guide pump light from the input end of the optical fiber to the output end of the optical fiber, and one or more inserts formed in the cladding surrounding the core. The core may have a geometry (e.g., a cross-sectional size, a helical pitch, and/or the like) that varies along a longitudinal length of the optical fiber, which may cause an absorption of the pump light to be modulated along the longitudinal length of the optical fiber.

A method is described for manufacturing an optical fiber preform, including a tube collapsing phase, and including monitoring the concentration of at least one fluid component of a fluid that is exhausted from the tube, to detect structural integrity of the tube. A system is also described for manufacturing optical fiber preforms. The system comprising a holder configured to hold a tube, a heater configured to heat at least part of the tube to a tube collapsing temperature, a fluid exhaust configured to discharge fluid from the tube, held by the holder. The system also includes a tube integrity monitor configured to monitor structural integrity of the tube, during a collapsing phase, by monitoring fluid that is discharged from the tube.

The invention relates to a method and a device for producing a preform for glass fiber production. The method comprises the steps of providing a carrier gas with a desired, precisely adjusted temperature, loading the carrier gas with halide vapor, mixing the loaded carrier gas with additional gases, and producing the preform in a reaction chamber with substrate.

Laser waveguides, methods and systems for forming a laser waveguide are provided. The waveguide includes an inner cladding layer surrounding a central axis and a glass core surrounding and located outside of the inner cladding layer. The glass core includes a laser-active material. The waveguide includes an outer cladding layer surrounding and located outside of the glass core. The inner cladding, outer cladding and/or core may surround a hollow central channel or bore and may be annular in shape.

An optical fiber includes: a central core portion; an intermediate layer formed around an outer circumference of the central core portion; a trench layer formed around an outer circumference of the intermediate layer; and a cladding portion formed around an outer circumference of the trench layer. Further, when, relative to the cladding portion, a relative refractive-index difference of the central core portion is Δ1, a relative refractive-index difference of the intermediate layer is Δ2, and a relative refractive-index difference of the trench layer is Δ3, relationships Δ1>Δ2>Δ3 and 0>Δ3 are satisfied and Δ1 is equal to or greater than 0.34% and equal to or less than 0.40%, |Δ3| is equal to or less than 0.25%, and Δ1×|Δ3| is less than 0.08%.sup.2.

A method of capturing soot includes the steps: combusting a first precursor in a burner to produce a soot stream, the soot stream comprising soot and exiting the burner at an outlet; and directing a capture medium to the soot stream, the capture medium contacting the soot in an impact region, the soot having a temperature greater than 50° C. in the impact region.

The present disclosure relates to a MCF, including a plurality of cores, an outer cladding or tube, diffusion barriers, and claddings. The diffusion barriers and claddings are designed so that unwanted migration of dopants from the inner cladding to the outer cladding or tube is reduced, or that unwanted migration of dopants from the cores to the outer cladding or tube is reduced. The doping levels of the various components of the MCF can be controlled in order to reduce dopant migration. The reduction in dopant gradients reduces the migration of dopants and bubbles to the interfaces between the inner claddings, the outer cladding or tube, and the cores.

The present disclosure provides a method for sintering of an optical fibre preform. The method includes manufacturing of the optical fibre preform. In addition, the method includes drying and sintering of the optical fibre preform. In addition, drying and sintering of the optical fibre preform results into a sintered optical fibre preform. Further, the method includes preparation of a glass rod from the sintered optical fibre preform. Furthermore, the method includes insertion of the glass rod into a centreline hole of the silica soot preform. The centreline hole is created by removing mandrel from the silica soot preform. Moreover, the method includes drying and sintering of the silica soot preform. Also, drying and sintering of the silica soot results into a sintered silica soot preform. Also, the method includes drawing of a rod from the sintered silica soot preform.

Disclosed herein are methods for forming an optical fiber preform using organic silica and germania precursors. The method includes depositing soot composed of germanium dioxide and silica on a substrate, removing the substrate, conducting a dehydration step and one or more heating steps under an oxygen-containing atmosphere to form the preform. Also disclosed are optical fibers drawn from the preforms produced herein.