Open AccessHigh efficiency, single-lobe surface-emitting DFB/DBR quantum cascade lasers
Author(s) -
Yinghui Liu,
Jinchuan Zhang,
Fang-Liang Yan,
Zhiwei Jia,
Fengqi Liu,
Liang Pan,
Ning Zhuo,
Shenqiang Zhai,
Lijun Wang,
Junqi Liu,
Shuman Liu,
Zhanguo Wang
Publication year - 2016
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.019545
Subject(s) - optics , materials science , quantum cascade laser , grating , optoelectronics , distributed bragg reflector , laser , lasing threshold , full width at half maximum , distributed bragg reflector laser , cascade , semiconductor laser theory , physics , chemistry , chromatography
We demonstrate a surface-emitting quantum cascade laser (QCL) based on second-order buried distributed feedback/distributed Bragg reflector (DFB/DBR) gratings for feedback and outcoupling. The grating fabricated beneath the waveguide was found to fundamentally favor lasing in symmetric mode either through analysis or experiment. Single-lobe far-field radiation pattern with full width at half maximum (FWHM) of 0.18° was obtained along the cavity-length direction. Besides, the buried DFB/DBR grating structure successfully provided an efficient vertical outcoupling mechanism with low optical losses, which manages to achieve a high surface outcouping efficiency of 46% in continuous-wave (CW) operation and 60% in pulsed operation at room temperature. Single-mode emission with a side-mode suppression ratio (SMSR) about 25 dB was continuously tunable by heat sink temperature or injection current. Our work contributes to the realization of high efficiency surface-emitting devices with high far-field beam quality that are significantly needed in many application fields.