Patent ID: 7142575

Claim:
A semiconductor laser element having a ridge-stripe structure for confining light in a horizontal direction, the element comprising: a substrate; a first conductivity type lower clad layer formed above the substrate; a second conductivity type upper clad layer formed above the lower clad layer, the second conductivity type being different from the first conductivity type; and an active layer provided between the lower clad layer and the upper clad layer, the element wherein, a difference in a radiation loss of light between a basic horizontal-lateral mode and a 1st-order horizontal-lateral mode is 10 cm −1 or more, the light generated in the active layer, the propagation loss of light directed toward a main side of at least either the lower clad layer or the upper clad layer, the main side being opposite to an active layer side of the lower clad layer or the upper clad layer.