Surface emitting quantum cascade laser

A surface emitting quantum cascade laser comprising:

• an active layer with a plurality of quantum well structures stacked therein, the active layer being capable of emitting laser light by inter-subband transition;
• a first semiconductor layer provided on the active layer and having a first surface provided with a plurality of pits so as to constitute a two-dimensional lattice;
• an insulating film filled in the plurality of pits and having a thickness equal to depth of the pits;
• and
• a first electrode covering the first surface of the first semiconductor layer and an upper surface of the insulating film and reflecting the laser light to the active layer side,
• each pit being asymmetric with respect to a line parallel to one side of the two-dimensional lattice, and
• the laser light reflected by the first electrode passing through the active layer and being emitted in a direction generally perpendicular to the active layer.

A surface emitting quantum cascade laser comprising:

• an active layer with a plurality of quantum well structures stacked therein, the active layer being capable of emitting laser light by inter-subband transition;
• a first semiconductor layer provided on the active layer;
• and
• a first electrode provided on the first semiconductor layer and provided with a plurality of pits so as to constitute a two-dimensional lattice,
• each pit being asymmetric with respect to a line parallel to one side of the lattice, and
• the laser light having passed through the plurality of pits being emitted in a direction generally perpendicular to a surface of the first electrode.