高功率长波红外分布反馈量子级联激光器相干阵列研究

The long-wave infrared quantum cascade laser (QCL) is pressing required for a wide range of important uses, such as free space communication, remote sensing and explosives monitoring. Based on our prevenient achievements on strain-compensated InGaAs/InAlAs QCLs, this project will focus on the study of QCL with high output power and stable single-mode emission in the long-wave infrared spectrum range. (1) The room temperature operated high power QCL will be achieved by precise controlling of material growth. The corresponding relations between strain, doping and device performance (threshold, characteristic temperature and power) will be investigated. (2) By embedding the coupled ridge waveguide distributed feedback QCL arrays integrated in parallel，coherent radiation will be achieved. The supermode theory will be investigated by changing the arrays parameter, such as period, number of array, interspaces and etching depth. Oscillation in the fundamental supermode will be achieved and then long-wave infrared QCL with high peak power and stable single-mode emission can be obtained. (3) The coherent radiation will be realized by evanescent wave coupling between micro-stripe distributed feedback arrays. Suppression of the higher order supermodes can be achieved by chirp structure design, where the lateral gain distribution was tailoring. Room temperature continuous wave operation of long-wave infrared QCL arrays will be present and high output power with stable single-mode emission can be obtained. This project will solve the basic problem of far-field pattern and thermal dissipation for a broad area QCL and break the power limitation of individual QCL.

长波红外量子级联激光器（QCL）在自由空间通信、遥感、毒品检查等方面有重要的应用需求。本项目拟在原有应变补偿InGaAs/InAlAs材料体系QCL的基础上，注入新的物理思想，实现长波红外QCL的高功率单模输出。（1）.发展长波红外QCL材料的可控制备理论，重点研究材料结构参数中应变、掺杂与器件性能的关联规律，奠定长波红外高功率QCL基础；（2）.利用耦合脊型波导分布反馈结构实现QCL阵列的相干辐射，研究阵列结构参数（周期、单元数量、单元间距、刻蚀深度等）对超模阶数的调控机理，实现脉冲高功率单模输出；（3）.利用衰逝波耦合实现分布反馈微米条结构QCL阵列的相干辐射，通过啁啾的结构设计调整阵列单元间的增益分配控制超模阶数，实现室温连续工作并获得高功率单模输出。通过本项目研究，可以解决宽脊QCL的远场和散热问题，突破单管器件输出功率的限制，为大功率、单模长波红外QCL研究提供全新的思路。

长波红外量子级联激光器（QCL）在自由空间通信、遥感、毒品检查等方面有重要的应用需求。本项目在原有应变补偿InGaAs/InAlAs材料体系QCL的基础上，注入新的物理思想，实现了长波红外QCL的高功率单模输出。（1）发展了长波红外QCL材料的可控制备理论，重点解决了材料结构参数中应变、掺杂与器件性能的对应关系，奠定了QCL材料基础；（2）利用耦合脊型波导分布反馈结构实现了QCL阵列的相干辐射，通过对耦合脊结构的单元间隔、周期等参数的控制实现了基超横模远场发射，横向远场发散角小于2.9°并获得了35W的峰值功率，阈值电流密度小于1.1 kA/cm2，边模抑制比（SMSR）大于30dB；（3）利用衰逝波耦合实现分布反馈微米条结构QCL阵列的相干辐射，得到了近衍射极限的远场发散角；（4）通过集成DBR结构获得了波长7.6微米、室温连续600mW的单模QCL，阈值电流密度小于1.5kA/cm2，SMSR 大于30dB。本项目发表了SCI论文21篇，部分结果发表在Applied Physics Letter、IEEE Photonics Technology Letter、Photonics Research等国际著名杂志上，器件指标达到了国际先进水平，申请国家发明专利7项，培养毕业生4人。