Quantum cascade laser device

Patent metadata

Field	Value
Publication number	US-2021351570-A1
Application number	US-202117313389-A
Country	US
Kind code	A1
Filing date	May 6, 2021
Priority date	May 8, 2020
Publication date	Nov 11, 2021
Grant date	—

Abstract

A quantum cascade laser device includes a semiconductor substrate, an active layer provided on the semiconductor substrate, and an upper clad layer provided on a side of the active layer opposite to the semiconductor substrate side and having a doping concentration of impurities of less than 1×1017 cm−3. Unit laminates included in the active layer each include a first emission upper level, a second emission upper level, and at least one emission lower level in their subband level structure. The active layer is configured to generate light having a center wavelength of 10 μm or more due to electron transition between at least two levels of the first emission upper level, the second emission upper level, and the at least one emission lower level in the light emission layer in each of the unit laminates.

First claim

1 . A quantum cascade laser device comprising:
a semiconductor substrate: an active layer provided on the semiconductor substrate and in which a cascade structure in which a light emission layer and an injection layer are alternately laminated is formed by laminating a unit laminate including the light emission layer and the injection layer in multiple stages; and a first clad layer provided on a side of the active layer opposite to the semiconductor substrate side and having a doping concentration of impurities of less than 1×10 17 cm −3 , wherein the unit laminates included in the active layer each include, in their subband level structure: a first emission upper level; a second emission upper level having an energy level higher than that of the first emission upper level; and at least one emission lower level having an energy level lower than that of the first emission upper level, and the active layer is configured to generate light having a center wavelength of 10 μm or more due to electron transition between at least two levels of the first emission upper level, the second emission upper level, and the at least one emission lower level in the light emission layer in each of the unit laminates.

2 . The quantum cascade laser device according to claim 1 , wherein a thickness of the first clad layer is 5 μm or more.

3 . The quantum cascade laser device according to claim 1 , wherein a doping concentration of impurities in the semiconductor substrate is less than 1×10 17 cm −3 .

4 . The quantum cascade laser device according to claim 1 , further comprising a second clad layer provided between the active layer and the semiconductor substrate and having a doping concentration of impurities of less than 1×10 17 cm −3 .

5 . The quantum cascade laser device according to claim 4 , wherein a thickness of the second clad layer is 5 μm or more.

6 . The quantum cascade laser device according to claim 4 , further comprising:
a first electrode provided on a side in which the active layer is disposed with respect to the semiconductor substrate and electrically connected to the first clad layer; and a second electrode provided on a side opposite to the first electrode with the semiconductor substrate interposed therebetween and electrically connected to the semiconductor substrate, wherein a doping concentration of impurities in the semiconductor substrate is 5×10 15 cm −3 or more and less than 1×10 17 cm −3 .

Assignees

• Hamamatsu Photonics Kk

Inventors

• Fujita Kazuue
• HITAKA Masahiro
• Sugiyama Atsushi
• Shibata Kousuke

Classifications

• H01S2302/02

  THz - lasers, i.e. lasers with emission in the wavelength range of typically 0.1 mm to 1 mm · CPC title

• H01S5/3402 Primary

  intersubband lasers, e.g. transitions within the conduction or valence bands · CPC title

• H01S5/22

  having a ridge or stripe structure · CPC title

• H01S5/12

  the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers (comprising a photonic bandgap structure H01S5/11; surface-emitting lasers H01S5/18) · CPC title

• H01S5/0604

  comprising a non-linear region, e.g. generating harmonics of the laser frequency · CPC title