US Patent 7173273 Semiconductor laser device

A semiconductor laser device has an n-GaAs substrate. On the n-GaAs substrate, by turns, are an n-AlGaInP cladding layer, an AlGaInP/GaInP MQW active layer, a p-AlGaInP first cladding layer, a single layer p-AlxGa1-xAs etching stopping layer, a p-AlGaInP second cladding layer with a stripe protrusion, and a p-GaAs contact layer. The portion, other than the stripe-form protrusion, of the p-AlGaInP second cladding layer is covered with an insulating film. The refractive index of the p-AlxGa1-xAs-ESL is nearly equal to the refractive index of each of the lower, first upper, and second upper cladding layers.