Variable ratio optical junction device

Claim 1

An optical junction device comprising first, second and third optical fibers, each comprising a core of transparent material surrounded by a layer of transparent cladding material having a refractive index lower than that of said core material, the end portions of said first and second fibers being fused together in side-by-side relationship, said end portions of said first and second fibers being fused together to such an extent as to form a single composite fiber having two cores therein, the cladding layers of said first and second fibers combining to form a single cladding layer of elliptical cross section, the endfaces of said first and second fibers being substantially coplanar and being substantially perpendicular to the fiber axes, means for supporting the end portion of said third optical fiber so that its axis is substantially parallel with the axes of said first and second fibers and its endface is substantially perpendicular to the axis thereof and is disposed against the endfaces of said first and second fibers, and means for causing relative movement between the endfaces of said first and second fibers and said third fiber, said movement causing the center of said third fiber to traverse a line passing through the centers of the endfaces of said first and second fibers.