Patent ID: 7711024

Claim:
A monolithic semiconductor laser comprising: a semiconductor substrate; a first wavelength semiconductor laser element provided on the semiconductor substrate, the first wavelength semiconductor laser element comprising a first wavelength light emitting layer forming portion which includes a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer which is formed so as to have a ridge portion, and a first conductivity type current constriction layer for the first wavelength semiconductor laser element provided on sides of the ridge portion of the second conductivity type semiconductor layer; and a second wavelength semiconductor laser element provided on a region of the semiconductor substrate, where the first wavelength semiconductor laser element is not formed, the second wavelength semiconductor laser element comprising a second wavelength light emitting layer forming portion which includes a first conductivity type semiconductor layer, an active layer and a second conductivity type semiconductor layer which is formed so as to have a ridge portion, and a first conductivity type current constriction layer for the second wavelength semiconductor laser element provided on sides of the ridge portion of the second conductivity type semiconductor layer, wherein the current constriction layers for the first and second wavelength semiconductor laser elements are made of the same material represented by Al z Ga 1-z As (0.5≦z≦0.8) and the material has larger band gap energy than that of the active layer of the second wavelength semiconductor laser element which emits light of a shorter wavelength than that of the first wavelength semiconductor laser element, and wherein the second conductivity type semiconductor layers having the ridge portion of the first and second wavelength semiconductor laser elements are made of materials which have a refractive index of 3.39 to 3.44 respectively, such that the difference between the refractive index and a refractive index of the current constriction layers for the first and second wavelength semiconductor laser elements is at most 0.1.