Patent ID: 7912104

Claim:
A semiconductor laser diode comprising: a first clad layer; a first optical guide layer over the first clad layer; an active layer over the first optical guide layer; a second optical guide layer over the active layer; and a second clad layer including aluminum over the second optical guide layer, wherein the second clad layer comprises a super-lattice layer that includes a first lattice layer and a second lattice layer, wherein band gap energy X values of the second lattice layer lie within a range of band gap energy X values of the first lattice layer, wherein the band gap energy X values of the first lattice layer decrease in a stepwise manner and the band gap energy X values of the second lattice layer decrease with a substantially continuous slope in a thickness direction based on a composition ratio of the aluminum, and wherein a first band gap energy X first lattice layer is greater than a second band gap energy X value of the first lattice layer, the first band gap energy X value of the first lattice layer corresponding to a position closer to the second optical guide layer than a position that corresponds to the second band gap energy X value of the first lattice layer, and wherein a first band gap energy X value of the second lattice layer is greater than a second band gap energy X value of the second lattice layer, wherein the first band gap energy X value of the second lattice layer corresponds to a position closer to the second optical guide layer than a position that corresponds to the second band gap energy X value of the second lattice layer.