Beam Profiling of a Commercial Lens-Assisted Terahertz Time Domain Spectrometer
Beam Profiling of a Commercial Lens-Assisted Terahertz Time Domain Spectrometer
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DOI：
10.1109/tthz.2020.3026656
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发表时间：
2021-01-01
影响因子：
3.2
通讯作者：
Navarro-Cia, Miguel
中科院分区：
文献类型：
--
作者：
Freer, Suzanna;Gorodetsky, Andrei;Navarro-Cia, Miguel
为了进行太赫兹光谱学和成像，并准确地设计和预测准光学元件的性能，从太赫兹源发射的光束（理想的高斯）的参数的知识是至关重要的。尽管它的扩散，在宽带太赫兹光导天线框架下，相对较少的工作已经完成。本文主要采用针孔扫描方法，结合逐步角谱模拟，研究了商用硅透镜集成太赫兹光导天线发射的光束的轮廓和偏振特性，并通过TPX（聚甲基戊烯）透镜准直。我们的研究指出了不同光束剖面方法的局限性及其对光束高斯估计的影响。观察到非高斯不对称光束，沿x和y方向的主瓣束腰在0.25太赫兹时分别为8.4+/-0.7 mm和7.7+/-0.7 mm，在1太赫兹时分别为1.4+/-0.7 mm和1.4+/-0.7 mm。此外，我们报告了相对于轴上共极性分量的最大交叉极性分量，分别为-11.6 dB和-21.2 dB，分别为0.25 THz和1 THz。
To undertake THz spectroscopy and imaging, and accurately design and predict the performance of quasi-optical components, knowledge of the parameters of the beam (ideally Gaussian) emitted from a THz source is paramount. Despite its proliferation, relatively little work has been done on this in the frame of broadband THz photoconductive antennas. Using primarily pinhole scanning methods, along with stepwise angular spectrum simulations, we investigate the profile and polarization characteristics of the beam emitted by a commercial silicon-lens-integrated THz photoconductive antenna and collimated by a TPX (polymethylpentene) lens. Our study flags the limitations of the different beam profiling methods and their impact on the beam Gaussianity estimation. A non-Gaussian asymmetric beam is observed, with main lobe beam waists along x and y varying from 8.4+/-0.7 mm and 7.7+/-0.7 mm at 0.25 THz, to 1.4+/-0.7 mm and 1.4+/-0.7 mm at 1 THz, respectively. Additionally, we report a maximum cross-polar component relative to the on-axis co-polar component of -11.6 dB and -21.2 dB, at 0.25 THz and 1 THz, respectively.