The principle and recent progress of the Terahertz Quantum-Cascade Lasers(QCL) are briefly introduced. The beam quality of different THz QCLs is studied. Beam patterns of continuous wave and pulse modes emitting devices are characterized by employing thermal detector arrays and THz Quantum-Well Photodetector(THz QWP), respectively. The detecting abilities of different arrays are compared and analyzed, and the differences in THz light characterizing between the array and THz camera are also compared. According to the results of the beam improvements, some methods of beam improvement for THz light from the THz QCL are put forward. The germanium(Ge) lens, silicon hyper hemisphere(high resistance) lens and polythene lens are good tools for improving the beam quality of THz QCLs except for employing fine waveguide fabrication process.% 简要介绍太赫兹量子级联激光器(THz QCL)的工作原理及其进展。研究多个器件输出激光的光束质量，分别采用热探测器阵列和 THz量子阱探测器(THz QWP)表征连续激射和脉冲激射THz QCL 激光的光束图形，对比分析不同热探测器阵列对 THz 激光的表征能力，比较热探测器阵列和 THz照相机对平行 THz激光表征的差异。分析光束改善后 THz激光光斑的尺寸、二维强度分布等特点，根据对 THz QCL输出激光的改善效果，给出采用外部手段改善 THz QCL激光光束的几种方法。研究表明，除了采用精细的波导工艺之外，锗(Ge)透镜、超半球高阻硅透镜和聚乙烯透镜都是外部改善技术中很好的手段。
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