Surface emitting semiconductor laser

Abstract

A surface emitting semiconductor laser comprising an active layer having a convex portion is disclosed in this specification. This surface emitting semiconductor laser has a structure in which an n-type first semiconductor layer, a p-type active layer and a p-type second semiconductor layer are formed one upon another on one surface of an n-type semiconductor substrate having a concave portion. The active layer has a convex portion corresponding to the concave portion of the semiconductor substrate. On the other surface of the semiconductor substrate, there is provided a negative electrode in the form of a ring surrounding the above stated concave portion. A positive electrode is electrically connected to the above stated second semiconductor layer through an insulating layer having a contact hole. A forbidden band width of the material forming the active layer is smaller than the respective forbidden band widths of the materials forming the other semiconductor layers. The active layer has a large refractive index with respect to the laser light to be oscillated, as compared with the refractive indexes of the other semiconductor layers. Under these conditions, the convex portion of the active layer functions as an optical convex lens. Laser light is generated in a direction perpendicular to the active layer and converged by the above stated convex lens so that it is emitted to the exterior.