Patent ID: 7218815

Claim:
An athermal arrayed-waveguide grating comprising: an input waveguide for inputting two or more optical signals; a grating array for separating the input optical signals into different light wavelengths; a first slab having a first layer and a second layer with different refractive indices from each other, said first layer being contiguous to the input waveguide, said second layer being disposed for coupling said first layer to the grating array; a second slab for causing the different light wavelengths separated at the grating array to be imaged on an egress surface thereof; and, an output-waveguide array for outputting each light wavelength imaged on the egress surface of the second slab in a form of a separated channel, wherein the second layer is interposed between the first layer and the grating array and comprises a refractive index that is equal to that of the input waveguide.