红外与毫米波学报, 2017, 36 (6): 706, 网络出版: 2018-01-04  

基于衍射光栅耦合输出的一级分布反馈太赫兹量子级联激光器

Terahertz first-order distributed feedback quantum cascade laser with light extraction via a diffraction grating
作者单位
1 中国科学院上海技术物理研究所 红外成像材料与器件重点实验室, 上海 200083
2 中国科学院大学, 北京 100049
摘要
对比研究了两种不同结构太赫兹波段的双金属波导一级分布反馈量子级联激光器(THz-DFB-QCL).提出并实现基于衍射光栅耦合输出的THz-DFB-QCL中, 太赫兹波通过衍射光栅而非解理腔面形成出射.计算表明, 优化衍射光栅的结构可实现约70%的激光输出效率和小于1%的反射率, 激光发散角约为10°×50°.极低的反射率可以有效抑制反射波对腔内谐振的干扰, 是获得单模激射的关键.实验上, 利用衍射光栅耦合输出的激光器实现了频率约2.58 THz的稳定单模激光, 边模抑制比达23 dB, 光束分布与理论计算相吻合.得益于较好的衍射效率和光束准直性, 相比于常规的解理腔面边发射激光器, 通过衍射光栅耦合输出显著提升了激光功率.
Abstract
We have studied two different kinds of terahertz first-order distributed feedback quantum cascade lasers (THz-DFB-QCL), both of which are based on a metal-metal waveguide. To realize stable single-mode emission, we have demonstrated for the first time THz-DFB-QCLs in which THz wave is extracted via a diffraction grating. Our simulations illustrate that an optimized diffraction grating will give rise to a diffraction efficiency of about 70%, and a reflectivity less than 1%. It will also result in a laser beam pattern with a low divergence angle of 10°×50°. Such a low reflectivity will keep the mode oscillation inside the DFB grating undisturbed, which is crucial to realize stable single-mode emission. Experimentally, by utilizing a diffraction grating to extract THz wave, we have realized THz-DFB-QCLs with stable single-mode emission near 2.58 THz and the side-mode-suppression-ratio is about 23 dB. The measured laser beam pattern is in good agreement with the calculations. Most importantly, due to the good diffraction efficiency and beam directionality, the diffraction grating based THz-DFB-QCL significantly improves the output power compared with the edge-emitting counterpart.

朱欢, 王芳芳, 颜全, 俞辰韧, 常高垒, 陈建新, 徐刚毅, 何力. 基于衍射光栅耦合输出的一级分布反馈太赫兹量子级联激光器[J]. 红外与毫米波学报, 2017, 36(6): 706. ZHU Huan, WANG Fang-Fang, YAN Quan, YU Chen-Ren, CHANG Gao-Lei, CHEN Jian-Xin, XU Gang-Yi, HE Li. Terahertz first-order distributed feedback quantum cascade laser with light extraction via a diffraction grating[J]. Journal of Infrared and Millimeter Waves, 2017, 36(6): 706.

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