Optical fibre couplers

Abstract From the Canadian patent

Optical fibre couplers are formed by selectively etching the cladding layer of portions of the fibres forming the coupler to provide them with an undulating profile converging a group of fibres so that the undulating profiles interlock, and fusing the interlocking portions without drawing the fibres, so as to form a fused coupling zone of blended core and cladding glass. The fused zone is inserted in a ferrule, or a cladding layer is applied having a numerical aperture selected to maintain a more or less constant numerical aperture through the coupler. Such couplers may be cut in half and the halves optically coupled to each other by applying lenses to the cut ends and inserting the halves …