Patent ID: 7656918

Claim:
A semiconductor laser having an n-cladding layer, a first optical guide layer, an active layer, a second optical guide layer, and a p-cladding layer above an InP substrate, wherein the active layer has a Be-containing group II-VI compound semiconductor mixed crystal layer, having a layer constituted with a matrix element identical with that of the Be-containing group II-VI compound semiconductor of the active layer in any one of the following layer configurations (1) to (8): (1) the first optical guide layer, (2) the second optical guide layer, (3) the first optical guide layer, and the second optical guide layer, (4) the n-cladding layer and the first optical guide layer, (5) the second optical guide layer and p-cladding layer, (6) the n-cladding layer, the first optical guide layer, and the second optical guide layer, (7) the first optical guide layer, the second optical guide layer, and the p-cladding layer, (8) the n-cladding layer, the first optical guide layer, the second optical guide layer, and the p-cladding layer; and a compositional ratio Xa of Be to the layer having Be of the layer configurations (1) to (8) and a compositional ratio Xb of Be to the layer having Be of the active layer satisfy a relation: 0.7 ×Xb<Xa< 1.3 ×Xb.