Semiconductor laser device

A semiconductor laser device comprising:

• a first conductivity type semiconductor substrate;
• a first conductivity type lower cladding layer disposed on the semiconductor substrate and having an energy band gap;
• an active layer disposed on the lower cladding layer and having an energy band gap smaller than the energy band gap of the lower cladding layer;
• a second conductivity type first upper cladding layer disposed on the active layer and having an energy band gap larger than the energy band gap of the active layer;
• a second conductivity type InGaP first etch stopping layer disposed on the first upper cladding layer and having an energy band gap larger than the energy band gap of the active layer;
• a ridge structure comprising a second conductivity type second etch stopping layer disposed on a central portion of the first etch stopping layer and a second conductivity type second upper cladding layer disposed on the second etch stopping layer, the second etch stopping layer comprising a material having an energy band gap larger than the energy band gap of the active layer, resistant to an etchant that etches the second upper cladding layer, and selectively etched by an etchant that does not etch the first etch stopping layer;
• first conductivity type current blocking layers disposed on the first etch stopping layer, contacting both sides of the ridge structure;
• and
• first and second electrodes respectively disposed on the substrate and the contact layer.