Semiconductor laser device

In a semiconductor laser device, the combination of:

• a substrate of a first conductivity type having a mesa;
• a first semiconductor layer of a second conductivity type which is formed on the upper surface of said substrate other than said mesa to form a flat plane including the top face of said mesa;
• a laser oscillation structure comprising a first cladding layer, an active layer for laser oscillation, and a second cladding layer, which is formed on said flat plane, wherein said active layer for laser oscillation is between said first and second cladding layers and above said mesa;
• and
• a multi-layer structure burying said laser oscillation structure, said multi-layer structure comprising a high resistance layer formed on said first semiconductor layer and burying both sides of said laser oscillation structure, and a second semiconductor layer of the first conductivity type formed on said high resistance layer.