Multiquantum barrier laser having high electron and hole reflectivity of layers

A semiconductor laser unit, comprising:

• an active layer;
• cladding layers between which said active layer is interposed;
• and
• a multiquantum barrier layer disposed between said active layer and one of said cladding layers, or disposed in one or both of said cladding layers close to said active layer, wherein
• said multiquantum barrier layer includes at least one first pair of a well layer and a barrier layer and at least one second pair of a well layer and a barrier layer, said first pair of well and barrier layers having different characteristics from said second pair of well and barrier layers to provide relatively high reflectivities with respect to electrons and/or holes at a plurality of primary symmetrical points in a reciprocal lattice space, or at respective positions close to the plurality of primary symmetrical points.

A semiconductor laser unit, comprising:

• an active layer;
• cladding layers between which said active layer is interposed;
• and
• a multiquantum barrier disposed between said active layer and one of said cladding layers, or disposed in one or both of said cladding layers close to said active layer, wherein
• said multiquantum barrier layer includes at least one first pair of a well layer and a barrier layer and at least one second pair of a well layer and a barrier layer, said first pair of well and barrier layers having different characteristics from said second pair of well and barrier layers to provide relatively high reflectivities with respect to electrons and/or holes at a .GAMMA.-point in a reciprocal lattice space or at a position close to said .GAMMA.-point in the reciprocal lattice space and at at least one of primary symmetrical points in the reciprocal lattice space except said .GAMMA.-point, or at a point close to the primary symmetrical point.

A semiconductor laser unit, comprising:

• an active layer;
• cladding layers between which said active layer is interposed;
• and
• laminated multiquantum barrier layers of different characteristics and of the AlGaInP material system and including a lamination of a pair of a GaInP well layer and an AlInP barrier layer, said laminated multiquantum barrier layers disposed between said active layer and one of said cladding layers, or disposed in one or both of said cladding layers close to said active layer, wherein
• said laminated multiquantum barrier layers have relatively high reflectivities with respect to electrons and/or holes at a plurality of primary symmetrical points in a reciprocal lattice space, or at respective positions close to the plurality of primary symmetrical points.

A semiconductor laser unit, comprising:

• an active layer;
• cladding layers between which said active layer is interposed;
• and
• laminated multiquantum barrier layers of different characteristics and of the AlGaInP material system and including a lamination of a pair of a GaInP well layer and an AlInP barrier layer, said laminated multiquantum barrier layers disposed between said active layer and one of said cladding layers, or disposed in one or both of said cladding layers close to said active layer, wherein
• said laminated multiquantum barrier layers having relatively high reflectivities with respect to electrons and/or holes at a .GAMMA.-point in a reciprocal lattice space or at a position close to said .GAMMA.-point in the reciprocal lattice space and at at least one of primary symmetrical points in the reciprocal lattice space except said .GAMMA.-point, or at a point close to the primary symmetrical point.