Optical fibre cables

Abstract

A method of making very long length e.g. 50 km of optical fibre submarine cable in which acrylate-coated fibres (5) are guided by a fixed lay plate (10) and embedded by a fixed trumpet shaped die (7) in a relatively soft thermoplastic polymer coating (3) (e.g. Hytrel-RTM) with a zero lay angle. The coating (3) is heat softened and carried on a kingwire (2). The partially-embedded fibres are encased in a second coating (12) of the polymer by conventional extrusion. The element is coated with a water blocking material as the element is encased in a tubular strength member comprising a conductive tube of copper or aluminium surrounded by two layers (24,25) of high tensile strength wires. A dielectric sheath of e.g. natural polyethelene is extruded over the wires. The structure of the cable limits the bending of the fibres to e.g. 0.6 m, so that very low losses can be achieved.

Dependencies are inferred from the claim text.