Surface-emitting quantum cascade laser

A surface-emitting quantum cascade laser, comprising:

• a substrate;
• a first cladding layer provided on the substrate;
• a mesa portion of a semiconductor stacked body stacked in a stacking direction and located on the first cladding layer, the mesa portion including
• a light-emitting layer emitting light due to an intersubband transition of a carrier,
• a photonic crystal layer including a plurality of pits either arranged as or forming a two-dimensional diffraction grating, and
• a second cladding layer located on the photonic crystal layer and located in the plurality of pits;
• a reflective film located at opposing sidewalls of the mesa portion;
• a Fabry-Perot resonator located in the mesa portion;
• and
• an insulating film,
• a width direction between the opposing sidewalls being perpendicular to the stacking direction, and a width of the mesa portion in the width direction being less than a width of the first cladding layer in the width direction,
• wherein
• the mesa portion includes a guide layer located between the first cladding layer and the light-emitting layer,
• a width of the guide layer is smaller than the width of the first cladding layer in the width direction,
• the width of the first cladding layer in the width direction is the same as a width of the substrate in the width direction,
• the first cladding layer protrudes in both directions in the width direction with respect to the mesa portion,
• wherein the light-emitting layer, photonic crystal layer, second cladding layer and guide layer each have the same width in the width direction,
• the insulating film is located between the reflective film and the sidewall of the mesa portion,
• the first cladding layer has an uppermost planar surface extending under the mesa, the insulating film and the reflective film, and
• the guide layer and the insulating film are formed directly on the uppermost surface of the first cladding layer.