Quantum cascade laser and method for manufacturing quantum cascade laser

A method for manufacturing a quantum cascade laser, comprising the steps of:

• forming a stacked semiconductor layer including an active layer on a substrate having a first region and a second region arranged in a first axis direction;
• forming a mask on the epitaxial stacked semiconductor layer, the mask having a stripe-shaped pattern disposed on the second region and an opening located on the first region, the stripe-shaped pattern extending in the first axis direction;
• forming a stripe-shaped semiconductor mesa on the second region and a groove on the first region by etching the stacked semiconductor layer using the mask;
• forming an insulating layer on an upper surface and an end facet of the stripe-shaped semiconductor mesa;
• forming an opening in the insulating layer on the upper surface of the stacked semiconductor layer so as to expose the upper surface of the stacked semiconductor layer through the opening of the insulating layer;
• forming a conductive layer on the insulating layer and in the opening of the insulating layer in contact with the upper surface of the stacked semiconductor layer;
• forming a metal layer on the conductive layer disposed on the upper surface and the end facet of the stripe-shaped semiconductor mesa;
• and
• dividing the substrate into a laser chip along a second axis direction intersecting the first axis direction at a bottom surface of the groove,
• wherein the end facet of the stripe-shaped semiconductor mesa is retreated from an end facet of the substrate to a boundary between the first region and the second region of the substrate in the first axis direction.