| 摘要 |
PURPOSE:To lower an oscillating threshold current and to enhance quantum efficiency at the same time, by providing at least one of an N-type impurity doped layer, which is provided between a quantum well layer and a P-type clad layer in an active layer, and a P-type impurity doped layer which is provided between the quantum well layer and an N-type clad layer. CONSTITUTION:A P-type lightguide layer 42 is provided between a multiple quantum well layers 43 and an N<+> type clad layer 3, and an N-type lightguide layer 45 is provided between the multiple quantum well layers 43 and a P<+> clad layer 5. These impurity doped layer are operated as electric charge sheets. As a result, the internal electric field in the region of the multiple quantum well layers 43 in an active layer 4 is alleviated. Therefore, oscillating threshold current is decreased in comparison with that of a conventional structure. Owing to the decrease in oscillating threshold current, the quantum efficiency of a QW laser is enhanced. |
