Method for manufacturing a primary preform for optical fibres
AssigneeDraka Comteq B.V.
InventorsJohannes Antoon Hartsuiker, Igor Milicevic, Mattheus Jacobus Nicolaas Van Stralen, Eric Aloysius Kuijpers
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Abstract
A method for manufacturing a primary preform for optical fibers using an internal vapor deposition process including the steps of providing a substrate tube having supply and discharge sides, surrounding at least part of the tube by a furnace set at a temperature T0, supplying doped or undoped gases via the supply side, creating a reaction zone to promote deposition, and moving the zone back and forth along the length of the tube between reversal points near the supply and discharge sides to form at least one preform layer, which at least one layer comprises several glass layers.
Claims13
A method for manufacturing a primary preform for optical fibres using an internal vapour deposition process, comprising the steps of:
- i) providing a hollow glass substrate tube having a supply side and a discharge side;
- ii) surrounding at least part of the hollow substrate tube by a furnace set at a temperature T0;
- iii) supplying germamiun-doped glass-forming gases to the interior of the hollow glass substrate tube via the supply side thereof;
- iv) creating a reaction zone with conditions such that deposition of glass on the inner surface of the hollow glass substrate tube will take place;
- and
- v) moving the reaction zone back and forth along the length of the hollow glass substrate tube between a reversal point located near the supply side and a reversal point located near the discharge side of the hollow glass substrate tube so as to form at least one preform layer on the inner surface of the hollow glass substrate tube, which at least one preform layer comprises several glass layers;
- wherein the temperature of the furnace that surrounds the hollow glass substrate tube is varied linearly relative to T0 as a function of the thickness of the at least one preform layer in a radial direction to compensate for heat increase to achieve a substantially constant refractive index value in the preform layer in the radial direction, wherein the temperature varies over the complete longitudinal axis of the substrate tube as a function of time and not as a function of position along the axis of the substrate tube during at least part of step v) to influence the gradient of the refractive index of the at least one perform layer in the radial direction and the alpha value in the manufacture of the primary preform.
Dependencies are inferred from the claim text.