Manufacture of an optical fiber preform with micro-wave plasma activated deposition in a tube

US4292063A · kind A · utility

Assignee

• Nortel Networks Limited · CA

Inventor

• Koichi Abe · Ottawa, CA

Key dates

• Filing date: May 5, 1980
• Grant date: Sep 29, 1981
• Expiry date: May 5, 2000

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S65/16
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

For making a preform for production of optical fiber, the preform including fused silica, particulate material is deposited on the inside wall of a glass tube while the tube is reciprocated through a microwave cavity for production of a plasma in the tube. Oxygen and a reactant gas containing silica are passed through the tube. Dopant material can be added to the gas mixture and the concentration of the dopant varied to vary the refractive index. After the deposit of a sufficient thickness of particulate material, it is fused. The material can be caused to fuse on to the inner wall of the tube or to shrink away from the inner wall and removed from the tube. When the material is fused onto the wall of the tube it can then be collapsed, then either drawn to a fiber or placed in a further tube and drawn to a fiber. When the fused material shrinks from the tube wall, then it is collapsed to a solid rod, placed in a tube and then drawn to a fiber.