Semiconductor laser element

A ridge waveguide semiconductor laser comprising:

• a first conductivity type InP substrate;
• and
• successively disposed on said InP substrate,
• a first conductivity type cladding layer of AlxGayIn1−x−yAs (0<x, 0<y, x+y<1),
• an active layer of Alx1Gay1In1−x1−y1As (0<x1, 0<y1, x1+y1<1),
• a second conductivity type cladding layer of Alx2Gay2In1−x2−y2As (0<x2, 0<y2, x2+y2<1),
• an InP cladding layer of the second conductivity type and having a ridge shape with respective opposed sides, each side including a first portion substantially perpendicular to said InP substrate and a second portion, between the first portion and said InP substrate, oblique to said InP substrate, so that said ridge has a first portion of uniform width and a second portion that becomes wider in a direction extending from the first portion toward said InP substrate, and
• a metal electrode covering the ridge shape of said InP cladding layer.

A ridge waveguide semiconductor laser comprising:

• a first conductivity type InP substrate;
• and
• successively disposed on said InP substrate,
• a first conductivity type cladding layer of AlxGayIn1−x−yAs (0<x, 0<y, x+y<1),
• an active layer of Alx1Gay1In1−x1−y1As (0<x1, 0<y1, x1+y1<1) having a main current path,
• a second conductivity type cladding layer of Alx2Gay2In1−x2−y2As (0<x2, 0<y2, x2+y2<1) wherein first and second higher resistance regions sandwich the main current path of said active layer, said first conductivity type cladding layer, and said second conductivity type cladding layer,
• an InP cladding layer of the second conductivity type, having a ridge shape, and opposite the main current path of said active layer, and
• a metal electrode in electrical communication with said InP cladding layer.