Semiconductor laser device capable of emitting laser beams of different

Abstract

A semiconductor laser device has a compound semiconductor substrate, a first semiconductor layer disposed on the compound semiconductor substrate, and a second semiconductor layer disposed on the first semiconductor layer. The second semiconductor layer has at least three thin film layers of at least two different semiconductor compounds, the film layers being laminated with the different semiconductor compound layers alternating. An electrically isolating region extends through the thickness of the second semiconductor layer and electrically divides the second semiconductor layer into first and second portions which differ in quantum level from each other. A third semiconductor layer is disposed on the second semiconductor layer, and first and second electrodes are disposed on the third semiconductor layer in positions for supplying current to the first and second portions, respectively, and a third electrode is disposed on the substrate at the surface thereof opposite to the first and second electrodes. When a voltage is applied between the third and first electrodes and the third and second electrodes, laser beams having different wavelengths are emitted from the first and second portions of the second semiconductor layer, respectively.