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Optical Engineering

Low-threshold external-cavity quantum cascade laser around 7.2 μm
Author(s): Zhibin Zhao; Lijun Wang; Zhiwei Jia; Jinchuan Zhang; Fengqi Liu; Ning Zhuo; Shenqiang Zhai; Junqi Liu; Zhanguo Wang
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Paper Abstract

Room-temperature continuous wave (CW) operation of a tunable external-cavity quantum cascade laser (EC-QCL) at center wavelength around 7.2 μm is presented. The EC-QCL was implemented in a Littrow configuration. The gain chip is based on a diagonal bound-to-continuum design with a high-reflection coating on the back facet. A two-layer antireflection (AR) coating consisting of Al2O3 and ZnSe was designed and deposited on the front facet of the chip to suppress the Fabry–Pérot modes. With this AR coating, single-mode tuning range of 128  cm−1 was achieved, from 1346.7 to 1475.3  cm−1 (6.78 to 7.43 μm). High side-mode suppression ratio over 30 dB was achieved near the center gain region. A very low-threshold current density of 0.89  kA/cm2 and a high output power of 50 mW were obtained when the EC-QCL was operated in CW mode at 20°C.

Paper Details

Date Published: 27 April 2016
PDF: 4 pages
Opt. Eng. 55(4) 046116 doi: 10.1117/1.OE.55.4.046116
Published in: Optical Engineering Volume 55, Issue 4
Show Author Affiliations
Zhibin Zhao, Institute of Semiconductors (China)
Lijun Wang, Institute of Semiconductors (China)
Zhiwei Jia, Institute of Semiconductors (China)
Jinchuan Zhang, Institute of Semiconductors (China)
Fengqi Liu, Institute of Semiconductors (China)
Ning Zhuo, Institute of Semiconductors (China)
Shenqiang Zhai, Institute of Semiconductors (China)
Junqi Liu, Institute of Semiconductors (China)
Zhanguo Wang, Institute of Semiconductors (China)

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