Patent ID: 7068695

Claim:
A semiconductor laser comprising: a substrate; a clad layer of a first conduction type formed on the substrate; an active layer formed on the clad layer of the first conduction type and having a multiple well structure alternately stacking well layers of an InGaAlP compound semiconductor and barrier layers of an InGaAlP compound semiconductor to emit light from an emission region by current injection toward first and second edges disposed oppositely in a propagation direction of light emitted from the emission region; a clad layer of a second conduction type formed on the active layer; a first window region formed near the first edge, in which the bandgap of the well layers is wider than the bandgap of the well layers in the emission region; and a second window region formed near the second edge, in which the bandgap of the well layers is wider than the bandgap of the well layers in the emission region and narrower than the bandgap of the well layers in the first window region, the difference in wavelength shift between the wavelength of the well layers in the second window region and the wavelength of the well layers in the emission region being from a value equal to or larger than 10 nm to a value equal to or smaller than 30 nm.