Abstract: An optical coupler with an input and 2.sup.n outputs comprises a plurality of substantially coplanar waveguides, each optically coupling said input to one of said 2.sup.n coupler outputs, said waveguides comprising a plurality of waveguide sections connecting n stages of Y-junctions disposed along each waveguide path in a tree and branch arrangement, and further comprises a first junction (J.sub.21), having an axis not parallel to that of said coupler, which is connected to two second junctions (J.sub.31, J.sub.32) by curved waveguide sections without singularities, wherein any inflection point along any one of the waveguides, between the input and the nth stage of the junctions, is situated at one of the n junctions along the waveguide path. The coupler may be successfully applied to splitters or combiners and carried out in integrated optics, and a method for designing the mask used in the manufacture of the integrated optics coupler is also described.