Patent ID: 8809906
Filing Date: 2014-08-19
Classification: G02B,G02F,H01L

Abstract:
1. A semiconductor optical device comprising: a first clad layer, a second clad layer and an optical waveguide layer sandwiched between the first clad layer and the second clad layer, wherein the optical waveguide layer includes a first semiconductor layer, a second semiconductor layer disposed on the first semiconductor layer and extending in one direction, and a third semiconductor layer covering a top surface of the second semiconductor layer, and wherein the first semiconductor layer includes an n-type region disposed on one side of the second semiconductor layer, a p-type region disposed on the other side of the second semiconductor layer, an i-type region disposed between the n-type region and the p-type region, and a p-i-n homojunction to which a forward voltage is applied and which includes the p-type region and the i-type region and the n-type region, and wherein the second semiconductor layer has a band gap narrower than band gaps of the first semiconductor layer and the third semiconductor layer, and wherein the band gap of the second semiconductor layer is set so that an absolute value of a variation of an equivalent refractive index of a three-layered rib portion including the second semiconductor layer, the third semiconductor layer and the first semiconductor layer on a lower side of the second semiconductor layer, which is produced by carrier injection into the three-layered rib portion, is larger than an absolute value of a variation of an equivalent refractive index of a two-layered rib portion which includes the second semiconductor layer and the first semiconductor layer on a lower side of the second semiconductor layer and has an identical size to the three-layered rib portion, which is produced by carrier injection into the two-layered rib portion.