Patent ID: 7085453

Claim:
An optical functional device comprising: a first optical waveguide; a second optical waveguide having an equivalent refractive index lower than that of the first optical waveguide; and a connection through which the first and second optical waveguides are connected along an optical axis, wherein the connection is formed by selectively enlarging the waveguide width of the second optical waveguide, wherein the first and second optical waveguides each include a core and cladding, wherein a difference between the equivalent refractive index of the first optical waveguide and that of the second optical waveguide is determined by the cladding, wherein the cladding of the first optical waveguide and that of the second optical waveguide are made of the same material, and wherein the difference between the equivalent refractive indices is determined by a difference between the thickness of the cladding of the first optical waveguide and that of the cladding of the second optical waveguide.