Northern Telecom Limited

Masamichi Yataki

Gary S Duck

Jozef Straus

William J Sinclair

Paul S Ertl

Glen W Dack

In a known optical cable, optical fibers are loosely laid in a number of grooves formed within an elongate plastics extrusion. Typically the grooves follow a helical path with periodically reversing pitch, the helices centered on a central longitudinal axis of the cable. A primary reason for the helical lay is to prevent the fibers from becoming stressed should a bend occur in the cable. A further benefit of loose laying of fibers in a helical groove of periodically reversing pitch is that any elongation of the cable core is not immediately transmitted to the fiber supported by it. The fiber will move from its initial loose laid position both in a direction towards the inside curve of the helix and in a direction towards the base of the grooves. When it bears against the cable core over an appreciable length, the fiber will then be subjected to tensile stress. By the invention, tolerance to core elongation is increased by arranging that the grooves at any point along the core cant towards the outside curve of the helix.

Optical cables

Optical fiber wound onto a take-up reel after production is invariably tensioned such that results of characterization tests performed on the wound fiber are markedly different from such results obtained when the fiber is untensioned. Doubly winding the fiber to minimize tension is a laborious procedure. The invention covers a reel which has an adjustable hub circumference. Adjustment can be made with the fiber wound onto the hub so allowing rapid characterization of the fiber prior to restoring the fiber and the hub to their normal storage positions for fiber shipment.

Adjustable reel

An optical switch having a light input side and a light output side where there are a plurality of optical waveguides with light collimating lenses on one of the sides with the lenses in spaced positions and, on the other side there is an optical waveguide with a light collimating lens. To enable light to be transferred between the latter waveguide and any of the other lenses, it is movable to bring its lens into any of a plurality of switch positions, each corresponding to the position of one of the other lenses, and means is provided to move the lens selectively between positions. In preferred arrangements, the plurality of lenses are arranged around at least one pitch circle but a linear arrangement of lenses is also possible. An electric stepping motor is ideally used for the switching operation.

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Ottawa, Canada

Masamichi Yataki