Quantum cascade laser element and quantum cascade laser device

A quantum-cascade laser element comprising:

• a semiconductor substrate;
• a semiconductor laminate formed on the semiconductor substrate to include a ridge portion configured to include an active layer having a quantum-cascade structure;
• an embedding layer including a first portion formed on a side surface of the ridge portion, and a second portion extending from an edge portion of the first portion on a side of the semiconductor substrate along a width direction of the semiconductor substrate;
• a metal layer formed on a top surface of the ridge portion, on the first portion, and on the second portion;
• and
• a dielectric layer disposed between the second portion and the metal layer,
• wherein the dielectric layer is formed such that a part of the second portion is exposed from the dielectric layer, and
• the metal layer is in direct contact with the second portion at the part,
• wherein, in a thickness direction of the semiconductor substrate, a surface of the second portion on a side opposite to the semiconductor substrate is located between a surface of the active layer on a side opposite to the semiconductor substrate and a surface of the active layer on a side of the semiconductor substrate, and
• a part of the metal layer on the first portion overlaps the active layer when viewed in the width direction of the semiconductor substrate.

A quantum-cascade laser element comprising:

• a semiconductor substrate;
• a semiconductor laminate formed on the semiconductor substrate to include a ridge portion configured to include an active layer having a quantum-cascade structure;
• an embedding layer including a first portion formed on a side surface of the ridge portion, and a second portion extending from an edge portion of the first portion on a side of the semiconductor substrate along a width direction of the semiconductor substrate;
• a metal layer formed on a top surface of the ridge portion, on the first portion, and on the second portion;
• and
• a dielectric layer disposed between the second portion and the metal layer,
• wherein the dielectric layer is formed such that a part of the second portion is exposed from the dielectric layer,
• the metal layer is in direct contact with the second portion at the part,
• wherein a thickness of the first portion of the embedding layer is thinner than a thickness of the second portion of the embedding layer.