Patent ID: 6304706
Filing Date: 2001-10-16
Classification: G02B

Abstract:
A planar lightwave circuit comprising:a plurality of nonparallel adjacent waveguides constituting a branching waveguide; andburied layers arranged between said adjacent waveguides,wherein said waveguides are made up of cores and surrounding clads,said buried layers are formed, in tight contact, between the cores to extend from a branching point from which the cores of said adjacent waveguides branch and to decrease in thickness as spacings between the cores of said adjacent waveguides increase with an increase in distance from the branching point,a refractive index of said buried layer is higher than that of the clad, anda refractive index of the core is not less than that of said buried layer,wherein the thickness of said buried layer linearly decreases from the branching point with a slope of said buried layer falling within a range of 0.25.degree. (inclusive) to 2.degree. (inclusive).