Patent ID: 7809042

Claim:
A two-wavelength semiconductor laser device comprising a first semiconductor laser device and a second semiconductor laser device each having a window structure in a vicinity of an optical resonator facet, on a first-conductivity type single crystal semiconductor substrate, wherein the first semiconductor laser device includes at least a first-conductivity type first cladding layer, a first guide layer made of AlGaAs mixed crystal, a first quantum well active layer having a barrier layer made of AlGaAs mixed crystal, a second guide layer made of AlGaAs mixed crystal, and a second-conductivity type second cladding layer, sequentially formed on the semiconductor substrate, the second semiconductor laser device includes at least a first-conductivity type third cladding layer, a third guide layer made of AlGaInP mixed crystal, a second quantum well active layer having a barrier layer made of AlGaInP mixed crystal, a fourth guide layer made of AlGaInP mixed crystal, and a second-conductivity type fourth cladding layer, sequentially formed on the semiconductor substrate, at least the barrier layer included in the first quantum well active layer, the first guide layer, and the second guide layer each have an Al molar ratio of more than 0.47 and 0.60 or less, a peak concentration of a first impurity in the first quantum well active layer in the window structure of the first semiconductor laser device is higher than a peak concentration of a second impurity in the second quantum well active layer in the window structure of the second semiconductor laser device, the peak concentration of the second impurity is 1×10 18 /cm 3 or more and 1×10 19 /cm 3 or less, a diffusion end closer to the semiconductor substrate of the first impurity in the window structure of the first semiconductor laser device is located in the first cladding layer, a diffusion end closer to the semiconductor substrate of the second impurity in the window structure of the second semiconductor laser device is located in the third cladding layer, and a distance from the first quantum well active layer to the diffusion end closer to the semiconductor substrate of the first impurity is smaller than a distance from the second quantum well active layer to the diffusion end closer to the semiconductor substrate of the second impurity.