Patent ID: 7787736

Claim:
A semiconductor optoelectronic waveguide comprising: an upper electrode layer; a lower electrode layer; a semiconductor core layer arranged between said upper and lower electrode layers, the semiconductor core layer having electro-optical effects; a first semiconductor clad layer arranged between said lower electrode layer and said core layer; a second semiconductor clad layer arranged between said upper electrode layer and said core layer, wherein the band gap of said first and second semiconductor clad layers is greater than that of said semiconductor core layer; a third semiconductor clad layer containing an n-type dopant which is arranged between said first semiconductor layer and said lower electrode layer; a fourth semiconductor clad layer which is arranged between the second semiconductor clad layer and said upper electrode layer; and a fifth semiconductor layer having a p-type dopant contained between the second semiconductor clad layer and the fourth semiconductor clad layer and whose band gap is greater than that of the semiconductor core layer, wherein said fourth semiconductor clad layer has: a major region of an n-type modulation waveguide formed as an inside part of the fourth semiconductor clad layer; and an isolation region adjacent to the major region having a p-type electrical conductivity, wherein said upper electrode layer is in contact with said isolation region and said major region, and said lower electrode layer is provided on the third semiconductor clad layer, and whereby voltage may be applied to the semiconductor core layer via said upper and lower electrode layers.