Patent ID: 9184567
Filing Date: 2015-11-10
Classification: B82Y,H01S

Abstract:
1. A quantum cascade laser comprising: a substrate having a conductivity type, the substrate having a principal surface and a back surface opposite to the principal surface, substrate having a first region, a second region, and a third region arranged in order along a direction perpendicular to a normal axis to the principal surface; a semiconductor lamination provided on the principal surface of the substrate, the semiconductor lamination including a mesa stripe section provided on the second region, an upper cladding layer having the same conductivity type as the substrate, a first burying layer, and a second burying layer, the mesa stripe section including a core layer for emission of light in the quantum cascade laser; a first electrode provided on the semiconductor lamination; and a second electrode provided on the back surface of the substrate, wherein the first burying layer is provided on the first region and one side face of the mesa stripe section, the second burying layer is provided on the third region and other side face of the mesa stripe section, the upper cladding layer is provided on the mesa stripe section, the first burying layer, and the second burying layer, the first burying layer includes a first current blocking layer and a third current blocking layer provided on the first current blocking layer, the second burying layer includes a second current blocking layer and a fourth current blocking layer formed on the second current blocking layer, the first current blocking layer has a first side portion in contact with the entire one side face of the mesa stripe section and a first bottom portion provided on the substrate, the second current blocking layer has a second side portion in contact with the entire other side face of the mesa stripe section and a second bottom portion provided on the substrate, the first current blocking layer and the second current blocking layer are comprised of a semiconductor material doped with a transition metal selected from the group consisting of Fe, Ti, Cr, and Co, the first blocking layer has a bandgap energy higher than a bandgap energy of the third current blocking layer, the second current blocking layer has a bandgap energy higher than a bandgap energy of the fourth current blocking layer, and the first and second current blocking layers have a larger band gap energy than that of the upper cladding layer.