The upper surface of the semiconductor substrate has a slope descending from the projection in the second direction at an angle of 0-12° to a horizontal plane. The mesa stripe structure has an inclined surface with a slope ascending from the upper surface of the semiconductor substrate at an angle of 45-55° to the horizontal plane, the mesa stripe structure having an upright surface rising from the inclined surface at an angle of 85-95° to the horizontal plane. The buried layer is made from semiconductor with ruthenium doped therein and is in contact with the inclined surface and the upright surface. The inclined surface is as high as 80% or less of height from the upper surface of the semiconductor substrate to a lower surface of the quantum well layer and is as high as 0.3 μm or more.

The upper surface of the semiconductor substrate has a slope descending from the projection in the second direction at an angle of 0-12° to a horizontal plane. The mesa stripe structure has an inclined surface with a slope ascending from the upper surface of the semiconductor substrate at an angle of 45-55° to the horizontal plane, the mesa stripe structure having an upright surface rising from the inclined surface at an angle of 85-95° to the horizontal plane. The buried layer is made from semiconductor with ruthenium doped therein and is in contact with the inclined surface and the upright surface. The inclined surface is as high as 80% or less of height from the upper surface of the semiconductor substrate to a lower surface of the quantum well layer and is as high as 0.3 μm or more.

The upper surface of the semiconductor substrate has a slope descending from the projection in the second direction at an angle of 0-12 to a horizontal plane. The mesa stripe structure has an inclined surface with a slope ascending from the upper surface of the semiconductor substrate at an angle of 45-55 to the horizontal plane, the mesa stripe structure having an upright surface rising from the inclined surface at an angle of 85-95 to the horizontal plane. The buried layer is made from semiconductor with ruthenium doped therein and is in contact with the inclined surface and the upright surface. The inclined surface is as high as 80% or less of height from the upper surface of the semiconductor substrate to a lower surface of the quantum well layer and is as high as 0.3 m or more.

A laser diode has a layer arrangement including a first layer structure extending along a Z axis in a longitudinal direction, along an X axis in a transverse direction and along a Y axis in a height direction, and a second and third layer structure arranged along the Z axis on opposite longitudinal sides of the first layer structure and adjoining the first layer structure, wherein the active zone of the first layer structure is arranged offset in height relative to the active zones of the second and third layer structures, and an intermediate layer is arranged laterally with respect to the first layer structure in the second and third layer structures, the intermediate layer configured as an electrically blocking layer that hinders or prevents a current flow, and the intermediate layer being arranged between the active zone and an n contact.

The upper surface of the semiconductor substrate has a slope descending from the projection in the second direction at an angle of 0-12 to a horizontal plane. The mesa stripe structure has an inclined surface with a slope ascending from the upper surface of the semiconductor substrate at an angle of 45-55 to the horizontal plane, the mesa stripe structure having an upright surface rising from the inclined surface at an angle of 85-95 to the horizontal plane. The buried layer is made from semiconductor with ruthenium doped therein and is in contact with the inclined surface and the upright surface. The inclined surface is as high as 80% or less of height from the upper surface of the semiconductor substrate to a lower surface of the quantum well layer and is as high as 0.3 m or more.

A laser diode has a layer arrangement including a first layer structure extending along a Z axis in a longitudinal direction, along an X axis in a transverse direction and along a Y axis in a height direction, and a second and third layer structure arranged along the Z axis on opposite longitudinal sides of the first layer structure and adjoining the first layer structure, wherein the active zone of the first layer structure is arranged offset in height relative to the active zones of the second and third layer structures, and an intermediate layer is arranged laterally with respect to the first layer structure in the second and third layer structures, the intermediate layer configured as an electrically blocking layer that hinders or prevents a current flow, and the intermediate layer being arranged between the active zone and an n contact.

A flip chip type laser diode includes a removable substrate, a first semiconductor layer, an emitting layer, a second semiconductor layer, at least one current conducting layer, a patterned insulating layer, at least one first electrode and a second electrode. The first semiconductor layer is disposed on the removable substrate. The emitting layer is disposed on a part of the first semiconductor layer. The second semiconductor layer is disposed on the emitting layer and forms a ridge mesa. The current conducting layer is disposed on a part of the first semiconductor layer. The patterned insulating layer covers the first semiconductor layer, the emitting layer, a part of the second semiconductor layer and a part of the current conducting layer. The first electrode and the second electrode are disposed on areas of the current conducting layer and the second semiconductor layer which are not covered by the patterned insulating layer.