介质透镜操控光电导天线辐射太赫兹波的研究

飞秒激光驱动的太赫兹 (terahertz, THz) 光电导天线是THz时域谱系统中常用的THz源，受全向辐射模式的影响，该光电导天线的天线主瓣小，方向性差。对波束的有效操控将有助于提高光电导天线的发射效率。以低温生长的砷化镓 (LT-GaAs) 作为天线基底材料，通过电磁仿真软件CST对蝶形天线辐射THz波的电磁分布特性进行仿真，研究了介质透镜对蝶形天线辐射出的THz波的操控。通过对透镜扩展厚度的理论与数值分析，得出一定频率下的最佳透镜扩展厚度值。仿真结果表明：随着频率的提高，蝶形天线在加载更小扩展厚度的硅透镜时可获得更好的方向性。

Study on terahertz wave emission from a dielectric- lens-controlled photoconductive antenna

The terahertz photoconductive antenna driven by femtosecond laser is a common terahertz source in terahertz time-domain spectroscopic system. Because of its omni-directional radiation mode, the main lobe of photoconductive antennas is small and its directivity is poor. The effective control of the wide-band terahertz beam is important to improve the emission efficiency of the photoconductive antennas. Using low-temperature growth gallium arsenide (LT-GaAs) as the substrate material of antenna, the electromagnetic distribution characteristics of terahertz wave radiated by the butterfly antenna are simulated by the electromagnetic software CST, and the effect of dielectric lens on terahertz wave radiated by a butterfly antenna is studied. The optimum expanding region thickness of lens is obtained by theoretical and numerical analysis. The simulation results show that with the increase of frequency, the butterfly antenna can obtain higher directivity with a thinner expanding region of the silicon lens.