Patent ID: 9525268
Filing Date: 2016-12-20
CPC Classification: H01S

Claim Text:
1. A quantum cascade laser comprising: a substrate having a principal surface including a first region and a second region arranged along a first axis; a laser structure disposed on the principal surface in the second region of the substrate, the laser structure having an end facet intersecting the first axis, the laser structure including a stripe-shaped stacked semiconductor layer extending along the first axis; and a distributed Bragg reflection structure disposed on the principal surface in the first region of the substrate, the distributed Bragg reflection structure including a semiconductor wall made of a single semiconductor material, the distributed Bragg reflection structure being optically coupled to the end facet of the laser structure, wherein the semiconductor wall has a first side surface and a second side surface opposite to the first side surface, the first side surface and the second side surface intersect the first axis and extend along a second axis intersecting the principal surface, the semiconductor wall is located away from the end facet of the laser structure, the end facet of the laser structure and the first and second side surfaces of the semiconductor wall are arranged along the first axis, the distributed Bragg reflection structure has a low-refractive-index portion disposed between the end facet of the laser structure and the first side surface and a high-refractive-index portion disposed between the first side surface and the second side surface, the low-refractive-index portion has a thickness along the first axis that is an odd multiple of λ/(4×n1), and the high-refractive-index portion has a thickness along the first axis that is an odd multiple of λ/(4×n2), where “λ” represents a lasing wavelength in vacuum, “n1” represents an effective refractive index of the low-refractive-index portion at the lasing wavelength, and “n2” represents an effective refractive index of the high-refractive-index portion at the lasing wavelength.