Quantum-cascade laser element and quantum-cascade laser device

2:

• The quantum-cascade laser element according to claim 1,
• wherein a width of the cladding layer in the first region is more than or equal to a width of the semiconductor mesa.

3:

• The quantum-cascade laser element according to claim 1,
• wherein a width of the cladding layer in the first region is less than or equal to four times a width of the semiconductor mesa.

5:

• The quantum-cascade laser element according to claim 4,
• wherein the opening is formed to expose a part of the cladding layer in the second region from the dielectric layer, and
• the metal layer is in contact with the cladding layer in the second region through the opening.

6:

• The quantum-cascade laser element according to claim 4,
• wherein a width of the opening in the width direction of the semiconductor substrate is more than or equal to two times a width of the semiconductor mesa.

7:

• The quantum-cascade laser element according to claim 4,
• wherein a width of the opening in the width direction of the semiconductor substrate is more than or equal to ten times the thickness of the cladding layer in the first region.

8:

• The quantum-cascade laser element according to claim 4, further comprising:
• a wire made of metal, that is electrically connected to the metal layer, and
• wherein a connection position between the metal layer and the wire overlaps the dielectric layer when viewed in the thickness direction of the semiconductor substrate.

9:

• The quantum-cascade laser element according to claim 1,
• wherein a thickness of the cladding layer in the second region is less than or equal to half the thickness of the cladding layer in the first region.

10:

• The quantum-cascade laser element according to claim 1,
• wherein the thickness of the cladding layer in the second region is 0, and
• the metal layer is formed over the cladding layer and the embedding layer.

11:

• The quantum-cascade laser element according to claim 1,
• wherein a surface of the cladding layer on a side opposite to the semiconductor substrate includes an inclined surface formed at a boundary portion between the first region and the second region, and
• when viewed in the light waveguide direction, the inclined surface is inclined to go outward as approaching the semiconductor substrate.

12:

• The quantum-cascade laser element according to claim 11,
• wherein when viewed in the light waveguide direction, the inclined surface is curved to protrude toward the active layer.

14:

• The quantum-cascade laser element according to claim 13,
• wherein the pair of groove portions reach the embedding layer.

15:

• The quantum-cascade laser element according to claim 13, further comprising:
• a plating layer formed on the metal layer,
• wherein a recessed portion is formed in a surface of the plating layer on a side opposite to the semiconductor substrate.

16:

• The quantum-cascade laser element according to claim 15,
• wherein a pair of the recessed portions are provided, and
• the pair of recessed portions overlap the pair of groove portions respectively when viewed in the thickness direction of the semiconductor substrate.

19:

• The quantum-cascade laser device according to claim 17,
• wherein the drive unit drives the quantum-cascade laser element to continuously oscillate laser light.