Patent ID: 9246308
Filing Date: 2016-01-26
CPC Classification: H01S

Claim Text:
1. A quantum cascade laser comprising: a semiconductor substrate including a principal surface; a mesa waveguide disposed on the principal surface of the semiconductor substrate, the mesa waveguide including a light emitting region emitting light at a wavelength and an upper cladding layer disposed on the light emitting region, the mesa waveguide extending in a direction orthogonal to a reference direction; and a current blocking layer formed on a side surface of the mesa waveguide, wherein the light emitting region includes a plurality of core regions and a plurality of buried regions that are made of materials different from materials of the core regions, at least one of the core regions has a width in the reference direction that is less than the wavelength of light emitted from the light emitting regions, the mesa waveguide is configured to form a single waveguide in which light in the light emitting region extends in the reference direction through the core regions, the core regions and the buried regions are alternately arranged in the reference direction, the core region at a central portion of the mesa waveguide has a width smaller than a width of the core region at a peripheral portion of the mesa waveguide in the reference direction, and the upper cladding layer is disposed on each of the core regions and the buried regions so that current is injected into the plurality of core regions from the upper cladding layer.