Patent ID: 9335469
Filing Date: 2016-05-10
CPC Classification: G02B

Claim Text:
1. A planar optical branching device comprising: a. a planar top cladding layer formed by a top cladding material; b. a planar lower cladding layer formed by a lower cladding material; c. a planar core layer immediately between said top cladding and lower cladding layers, wherein waveguides are formed by core material limited by cladding material; and d. a pair of branching channel waveguides in said core layer branching from a main waveguide defining between them an intermediate region, a z-axis extending along the direction of light propagation of the combined light distribution in said waveguides, an x-axis extending transverse to the z-axis and in a plane of the planar optical branching device, and a y-axis extending normal to the plane of the planar optical branching device, wherein said intermediate region comprises a plurality of holes of cladding material extending from the top of the core layer into intermediate material and in a direction parallel to the y-axis, said holes having a pitch defined as the center to center distance between two holes along said z-axis, said holes being arranged so that the depth of said holes in the direction parallel to the y-axis increases away from said main waveguide with an average slope as a function of distance from said main waveguide of less than 10% over at least 30% of said intermediate region.