A planar laser diode includes a substrate, a first multilayer structure on the substrate and formed of an alternate stacking of a first epitaxial layer and a second epitaxial layer, a cavity structure provided on the first multilayer structure and including an undoped active layer for producing optical radiation as a result of stimulated emission, a second multilayer structure provided on the cavity structure and formed of an alternate stacking of a third epitaxial layer and a fourth epitaxial layer, a first electrode structure on a bottom surface of the substrate, a second electrode structure for injecting carriers to said active layer via said cavity structure, an optical passage provided in one of the first and second electrode structures for allowing an optical beam to pass therethrough; a a current path structure provided between the second electrode structure and the active layer for providing a passage of the carriers, a current confinement structure for confining the passage of the carriers such that said carriers flow along a path generally coincident to an optical path of the optical beam, and a conductive region provided in contact with said the electrode structure for causing the carriers to flow therethrough, wherein the conductive region is provided so as to avoid the optical path.