title: Quantum dot cascade laser.
abstract: We demonstrated an unambiguous quantum dot cascade laser based on InGaAs/GaAs/InAs/InAlAs heterostructure by making use of self-assembled quantum dots in the Stranski-Krastanow growth mode and two-step strain compensation active region design. The prototype generates stimulated emission at λ ~ 6.15 μm and a broad electroluminescence band with full width at half maximum over 3 μm. The characteristic temperature for the threshold current density within the temperature range of 82 to 162 K is up to 400 K. Moreover, our materials show the strong perpendicular mid-infrared response at about 1,900 cm-1. These results are very promising for extending the present laser concept to terahertz quantum cascade laser, which would lead to room temperature operation.
  42.55.Px; 78.55.Cr; 78.67.Hc.
authors.forename: Ning
authors.initials: N
authors.lastname: Zhuo
authors.affiliation: Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P, O, Box 912, Beijing 100083, China. fqliu@red.semi.ac.cn.
authors.forename: Feng Qi
authors.initials: FQ
authors.lastname: Liu
authors.forename: Jin Chuan
authors.initials: JC
authors.lastname: Zhang
authors.forename: Li Jun
authors.initials: LJ
authors.lastname: Wang
authors.forename: Jun Qi
authors.initials: JQ
authors.lastname: Liu
authors.forename: Shen Qiang
authors.initials: SQ
authors.lastname: Zhai
authors.forename: Zhan Guo
authors.initials: ZG
authors.lastname: Wang