Patent ID: 7848602

Claim:
An arrayed waveguide grating structure comprising: an input star coupler; an output star coupler; and a plurality of arrayed waveguides optically connecting the input star coupler and the output star coupler, wherein each of the arrayed waveguides comprises a core pattern through which an optical light travels, wherein the core pattern comprises at least one first section having a first confinement factor and at least two second sections having a second confinement factor, the first confinement factor being higher than the second confinement factor, wherein the confinement factor is a characteristic parameter representing a degree of local distribution of guided mode in the core pattern of the arrayed waveguide, wherein the core pattern comprises at least two approximately linear sections, and at least one bending section having a radius of curvature smaller than the radius of curvature of the approximately linear sections, wherein the bending section forms the first section and the approximately linear sections form the second sections, and wherein at least one of the approximately linear sections of each arrayed waveguide comprises: at least one linear section having a confinement factor lower than the first confinement factor; and a gently curved section having a radius of curvature greater than that of the bending section, wherein the linear section of each arrayed waveguide has different length from the linear sections of the remaining arrayed waveguides.