Sheathed optical fiber cable

US4859023A · kind A · utility

Assignee

• American Telephone and Telegraph Company, AT&T Bell Laboratories · US

Inventors

• Bernard R. Eichenbaum · Lilburn, US
• Manuel R. Santana · Lutz, US

Key dates

• Filing date: Sep 21, 1981
• Grant date: Aug 22, 1989
• Expiry date: Sep 21, 2001

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B6/4486
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

Optical fiber cables have an inner sheath extruded or otherwise applied to surround optical fibers. If the fibers are coupled to the sheath, substantial shrinkage of the sheath during manufacturing induces microbending losses in the optical fibers. The inventive technique involves choosing a sheath material having a low viscoelastic modulus, typically PVC, and the application of tension thereto during or after extrusion that prevents such shrinkage. This approach typically avoids the necessity of including longitudinal compressive strength members in the cable. A filled optical fiber cable having a flexible gel to prevent water entry advantageously uses the present technique.