Quantum dot cascade laser

Ning Zhuo,Zhan Guo Wang,Feng Qi Liu,Li Jun Wang,Jin Chuan Zhang,Shen Qiang Zhai,Jun Qi Liu

doi:10.1186/1556-276x-9-144

Ning Zhuo, Zhan Guo Wang + Show 5 more

Open Access

https://doi.org/10.1186/1556-276x-9-144

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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.PACS42.55.Px; 78.55.Cr; 78.67.Hc

Highlights

Quantum cascade lasers are semiconductor laser sources based on intersubband transitions in multiple quantum well systems [1]
In order to restrain the appearance of unavoidable InAs quantum dashes on In0.53Ga0.47As, In0.52Al0.48As, and In0.53Al0.24Ga0.23As layers lattice-matched to InP substrate, the InAs quantum dots (QDs) are grown on tensilestrained In0.44Al0.56As and caped by GaAs to increase the lattice mismatch between InAs and embedding materials system
In the X-ray diffraction (XRD) simulation, we treated the QD layer as a two-dimensional InAs layer with a homogeneous thickness corresponding to the nominal deposit amount, which was strained biaxially to match the lattice constant of InP

Summary

Introduction

Quantum cascade lasers are semiconductor laser sources based on intersubband transitions in multiple quantum well systems [1]. Their unique operation principle and good performance have established themselves as the leading tunable coherent semiconductor source in the infrared and terahertz ranges of the electromagnetic spectrum [2-10]. Due to intersubband selection rules, the emitting light is polarized in the growth direction, which makes surface emission impossible. Another drawback is that due to numerous in-plane scattering paths that the electrons undergo and decrease the upper lasing state lifetime, the threshold current is increased and the wall plug efficiency is decreased [12-17]. An appealing and ambitious route to tackle these difficulties is to explore quantum dot cascade laser (QDCL) [17,18], by substituting the quantum wells (QWs) in the active region with selfassembled quantum dots (QDs)

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