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Advanced Optical Fibre Fabrication

April 6, 2016 Facebook Twitter LinkedIn Google+ Advertising News

Fibre optic cables are used today as a telecommunication and networking medium with more than 200 million km produced each year. They offer high speed, reliable transmission lines for calls and data, however, increased transfer rates are demanded to meet the growth of consumer usage – in particular video streaming.  To achieve this objective lower attenuation rates to further decrease error rates per Gb are needed which is related to the quality of the fibres themselves and their design.  The purer the fibre structure (nearer to theoretical limits) the lower the losses and so efforts to provide the highest calibre of materials for fabrication of the fibres have received significant effort.  Emerging fields around fibre amplifiers, lasers and sensors have taken advantage of this ability to prepare high quality structures.

In more detail the optical fibres are based on Silicon oxide that has been doped with suitable metals to provide the best properties.  A wide range of dopants has been studied with Rare Earth metal oxides seen as a major advance.  A Modified Chemical Vapour Deposition (MCVD) technique is used to apply the correct material composition inside a hollow Preform.  Overcladding is performed to modify refractive index profiles and fibre properties as required.  The Preform with its coatings is heated to a point where it begins to flow and then it is pulled at a controlled speed onto rollers to create a long fibre of the correct diameter.  The high temperatures employed create a diffusion profile which must be well understood to achieve the best results.

The nature of the dopant influences properties and an element of high interest is Ytterbium because its ions have a broad emission, a long lifetime in the excited state and can be incorporated into the silica host in relatively high concentrations.  By adapting alumina-phospho-silicate and phosphor-silicate glass matrices optical fibres for high power applications have been made that can enable faster more accurate data transfer.

The use of RE chelates has been shown to be advantageous for uniform doping of these glasses as they are formed to further improve homogeneity throughout the fibre length and thus reduce losses and EpiValence offers the highest purity Ytterbium Tetramethylheptanedionate for this specific application – note a special 5N grade is available on request.  Low levels of contaminant ions ensures only the active Yb is present to provide the maximum output from the fibre.

Other Rare Earth dopant materials based on the same chemistry to ensure compatibility are available (ie Cerium, Erbium) and a full list of suitable chemicals is available on the EpiValence website www.epivalence.com