Terraced substrate semiconductor laser

In a semiconductor laser, the improvement comprising a terrace-shaped semiconductor substrate having an upper face, a lower face and a step part disposed between said upper face and said lower face,

• a clad layer formed on said substrate includes an upper part, a lower part and a central part, said upper part being on said upper face, said lower part being on said lower face, and said central part connecting said upper and lower parts and being thicker than said upper part and said lower part in a manner that a step-shaped downward bending surface of said central part is located above said lower face,
• an active layer formed on said clad layer includes an upper lateral part, a lower lateral part, a center part connecting said upper and said lower lateral parts, a lasing region being a part of said upper lateral part near a bending part on said step-shaped downward-bending surface, and
• a current injection electrode is disposed above said lasing region.