PURPOSE: To obtain a large beam output by a method wherein an N type clad layer and a P type clad layer holding an active layer buried in the interior of a groove between them is surrounded with a multilayer semiconductor layer and the current injected in through a Zn diffusion region is exhaustively used for oscillation.

CONSTITUTION: A first multilayer semiconductor layer is formed on a semiconductor substrate 10 with a clad layer 11, a guide layer 12 and a clad layer 13. A stripe-shaped groove; whose widths in the vicinites of both refractive surfaces thereof are made narrow to the longitudinal direction of the resonator, width of the central part thereof is made wide and pointed end thereof reaches the substrate 10 in a region of the central part; is formed. A second multilayer semiconductor layer, which is formed by burying the interior of the groove and the external region thereof in a stripe structure with a clad layer 15, which has the same conductive type as that of the substrate 10; an active layer 16, which is formed adjacent to the layer 15 and whose position in the groove interior is included in the thickness of the guide layer in the vertical direction; and a clad layer 17, which is adjacent to the layer 16 and has a reverse conductive type to the layer 15; is provided, and the current injected in through the Zn diffusion region is effectively sent to the active layer 16 and contributes to oscillation.