Optical waveguide intersections without light leak

An optical waveguide intersection on the same level, inducing no light leak, with higher refractive index in the intersecting point than in the guides, is proposed. This intersection is formed easily by the photopolymerization method, introducing double exposure at the intersecting point (typical guide width, ~0.1 mm; Deltan ~0.5% in the guide; and ~1% in the intersection). Very low losses were observed in the intersections, while large leak losses were observed in ordinary intersections, where the refractive index was equal to that of the guides. Observed losses were in good agreement with calculated ones.