Precise positioning of optical fibers

US4474469A · kind A · utility

Assignee

• Nortel Networks Limited · CA

Inventor

• Koichi Abe · Ottawa, CA

Key dates

• Filing date: Apr 19, 1982
• Grant date: Oct 2, 1984
• Expiry date: Apr 19, 2002

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B6/2551
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

Before splicing optical fibers having cladding and core of differing refractive index, the cores are axially aligned. The fiber ends are held apart with the fibers approximately coaxial. The fiber end surfaces are then illuminated and reflected light is monitored. Since reflectivity is a function of refractive index, the position of the core in the reflectivity profile of each surface can be readily identified. The fiber ends can then be manouvered transverse of the fiber axes to bring the fiber core centers into registration with a datum line. The fiber ends are then brought close together for splicing. Previously, fibers having nominally identical outside diameters were aligned simply by pressing them into a common V groove, the optical transmission efficiency then depending on fiber/core concentricity. Alternatively, light was injected into the far end of one fiber, monitored at the far end of the other fiber, and the fibers at their near end manipulated to maximize monitored optical power. The present invention provides an easier and cheaper method of ensuring core alignment especially for monomode fibers.