Patent ID: 7310469

Claim:
A waveguide PIN (p-type, intrinsic, n-type) photodiode comprising: a lower light guide layer comprising a plurality of lower-sub-light-guide-layers formed on a substrate, wherein each lower-sub-light-guide-layer has a refractive index different from the other lower-sub-light-guide-layers; a light absorption layer formed on the lower light guide layer; an upper light guide layer comprising a plurality of upper-sub-light-guide-layers formed on the light absorption layer, wherein each upper-sub-light-guide-layer has a refractive index different from the other upper-sub-light-guide-layers; and a cladding layer formed on the upper light guide layer, wherein the lower light guide layer, the light absorption layer, and the upper light guide layer constitute a core layer, which is an optical waveguide, and wherein the refractive indices of the lower-sub-light-guide-layers and the upper-light-guide-layers are symmetrical with respect to the light absorption layer having a highest refractive index.