连续波单模太赫兹半导体激光器研究

Terahertz quantum cascade lasers are novel semiconductor optoelectronic devices designed with “Energy band engineering”. This kind of terahertz devices is compact, coherent, and easy-integration in nature. This project will focus on the problem of the high efficient, continuous-wave, and narrow-linewidth single-mode operation. It is of a great significance, for the high-resolution “fingerprints” spectrum and coherent terahertz imaging, that a joint breakthrough of these issues is made. In this project, we will carry out a collaborative research on device physics, material growth, and device processing. Moreover, we especially work on the mechanisms discovery, model establishment and process innovation. The key problem will be solved systematically in areas of the optical gain and quantum efficiency dominated by microstructure fluctuation, the heat dissipation mechanism in micro- and nano-scale, the single-mode vertical surface emitting and beam control of TM polarized devices. At the end of this project, high-efficiency, continuous-wave and single-mode terahertz quantum cascade lasers in the range of 2~5 THz will be achieved, also the relative theory and technology.

太赫兹量子级联激光器是基于“量子工程”设计的新型半导体太赫兹光电子器件，本身具有结构紧凑、相干、易集成的特点。本课题旨在突破太赫兹量子级联激光器的连续波、窄线宽单模及高功率效率问题。这些问题的协同突破将对在太赫兹波段发展高分辨率“指纹”光谱和相干成像等先进信息技术具有重要意义。本项目将器件物理研究与材料制备及器件工艺创新结合起来，开展有重点地系统研究，致力于解决材料微观结构对器件光学增益和量子效率的调控机制、高功率连续波太赫兹量子级联激光器微纳尺度热耗散机制、横磁极化器件的单模垂直面发射及光束调控机制等关键科学问题。预期能够揭示限制器件性能的新机理、建立精确的理论模型，创新工艺技术和方法解决高性能芯片和器件研制的瓶颈问题，最终研制出2-5 THz范围内稳定单模工作的高效率连续波太赫兹量子级联激光器。

高分辨率THz外差光谱技术和THz相干成像技术的发展对红外天文学、生物医学以及公共安全领域具有重要意义。这些前沿的应用需求，对THz量子级联激光器的综合性能提出了更高要求。本项目以研究连续波单模THz量子级联激光器为出发点，瞄准提高有源区材料的净增益，改善有源区材料的热耗散，寻求有效的集成化光栅耦合技术等有限目标，重点突破。理论研究了激光材料微观结构影响器件性能的关键因素，掌握了其内在机理，设计出高效率的THz量子级联激光材料；研究了千层异质结构材料组分、厚度、界面、应变、掺杂的协同控制方法，实现了超多周期材料分子束外延生长的精准控制。研究了高功率连续波THz量子级联激光器的热耗散机制，掌握器件倒装焊和横向微观辅助散热工艺。研究了不同形式分布反馈光栅的耦合机理，研制出系列高效率THz量子级联激光器，实现了连续波单模工作。.本项目实现了2.8-5.2 THz范围内多频段量子级联激光器连续波工作，其中最高连续波功率>200mW，最高峰值总功率>1.6 W；实现单模器件工作温度>77K，边模抑制比>25dB，功率>20mW。发表学术论文10篇，国际学术会议论文2篇，申请国家发明专利4项。