Method of producing optical fibers
AssigneeU.S. Philips Corporation
InventorDieter Kuppers
Life of this patent
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Abstract
Doped silica glass is deposited by means of reactive deposition from the gas phase by the action of a nonisothermal plasma, on the inside of a quartz glass tube. The coated tube is collapsed and the preform thus obtained is drawn into an optical fiber. During the deposition procedure the tube inside diameter between 6 and 30 mm must satisfy the formula (M/A.sub.I) 1/3.58.times.1 mm.ltoreq.d wherein M is the deposition rate of doped quartz glass in grams per minute and A.sub.I has the value 1.42.times.10.sup.-4 g/min. At the end of the deposition, prior to collapsing, the inside diameter must satisfy the equation (M/A.sub.II) 1/3.04.times.1 mm.gtoreq.d A.sub.II having the value 6.63.times.10.sup.-5 g/min.
Claims8
A method of producing optical fibers comprising the steps of:
- providing a silica glass tube;
- depositing a coating of silica glass, with or without a dopant, on the interior of the tube, said deposition being achieved by introducing a reactive gas mixture of glass-forming compounds into the tube and forming a nonisothermal plasma within the tube;
- collapsing the coated tube;
- and
- drawing the glass tube into a fiber;
- CHARACTERIZED IN THAT during the deposition step
- M/(A.sub.I .times.3.58).times.1 mm.ltoreq.d,
- where M is the instantaneous deposition rate in grams per minute, d is the inside diameter of the tube at the time of deposition and A.sub.I equals 1.42.times.10.sup.-4 grams per minute.
A method of producing internally coated glass tubes by depositing a coating of glass layers on the interior to the tube, said method comprising the steps of:
- introducing a reactive gas mixture into the tube;
- and
- forming a nonisothermal plasma zone within a portion of the tube;
- CHARACTERIZED IN THAT the deposition rate, M, in grams per minute is less than or equal to the product of 5.0836 times 10.sup.-4 grams/minute-millimeter times the inside diameter of the tube, d, in millimeters at the time of deposition.
A method as claimed in claimed 5, CHARACTERIZED IN THAT the glass tube and the deposited layers comprise silica.
Dependencies are inferred from the claim text.