Optic coupler

A fiber optic coupler comprising

• an elongated body of matrix glass, said body having end regions of given diameter, and a central region which tapers from said given diameter to a diameter smaller than said given diameter,
• a plurality of optical fibers extending longitudinally through said body, said fibers having at least a core and a layer of cladding glass, the refractive index of said cladding glass being greater than that of said matrix glass, the diameters of said optical fibers in said central region being smaller than the diameters thereof at said end regions, said cores being more closely spaced at said central region than at said end regions, the distance between said cores in said central region being sufficiently close that energy propagating in one of said fibers couples to the other of said fibers, the diameters of said cores in said central region being no smaller than 1/20 the diameters thereof at said end regions.

A fiber optic coupler comprising

• an elongated body of doped SiO.sub.2 matrix glass, said body having end regions of given diameter, and a central region which tapers from said given diameter to a diameter smaller than said given diameter,
• a plurality of linearly disposed, untwisted optical fibers extending longitudinally through said body, said fibers having at least a doped SiO.sub.2 core and a layer of SiO.sub.2 cladding glass, said cores being more closely spaced in said central region than in said end regions, the refractive index of said cladding glass being greater than that of said matrix glass, said matrix glass being integrally bonded to said fibers throughout at least that part of said central region at which said cores are sufficiently close that energy propagating in one of said fibers couples to the other of said fibers, whereby the interface between said fibers and said matrix glass in the energy coupling region is free from interstices, the diameters of said optical fibers in said central region being smaller than the diameters thereof at said end regions, the diameters of said cores in the central region being no smaller than 1/20 the diameters thereof at said end regions.

A fiber optic coupler for transferring energy from one input optical fiber to at least one other input optical fiber, said coupler comprising

• an elongated body of matrix glass, said body having end regions of a given diameter, and a central region which tapers from said given diameter to a diameter smaller than said given diameter, the minimum diameter of said central region being sufficiently great that said coupler is a self-supporting structure,
• a plurality of light-conducting glass cores extending longitudinally through said body, the refractive index of said cores being greater than that of said matrix glass, the diameters of said cores in said central region being smaller than the diameters thereof at said end regions but being no smaller than 1/20 the diameters thereof at said end regions, the spacing between said cores in said central region being less than the spacing between said cores in said end regions, the spacing between said glass cores in said central region being sufficiently small that energy propagating in one of said cores couples to the other of said cores.