论文标题
由波导模式选择控制的自由空间子纹兹尔兹田间极化
Free-space sub-terahertz field-polarization controlled by waveguide-mode-selection
论文作者
论文摘要
我们通过实验研究从配备有对角线角天线的多模矩形波导发出的自由空间电磁场。使用215-580 GHz的频率范围，光合物用于启动自由空间圆形的电磁场，通过输入对角线 - 霍恩 - 霍恩 - 霍恩·天线在矩形波导的输入处令人兴奋的多种模式。使用第二个光合物，以及硅镜菲涅耳散射器，用作对极化敏感的相干检测器的表征。我们发现，基本波导模式激发的辐射场的特征是线性极化。另外，我们发现辐射场的极化会在波导中有选择性地令人兴奋的高阶模式旋转45度。尽管具有较高的模式，但辐射场似乎维持了主要的高斯光束特性，因为与检测器的单向耦合是可能的，而单向性则与频率无关。我们讨论了这一发现的可能应用。
We study experimentally the free-space electro-magnetic field emitted from a multimode rectangular waveguide equipped with a diagonal-horn antenna. Using the frequency range of 215-580 GHz, a photo-mixer is used to launch a free-space circularly-polarized electro-magnetic field, exciting multiple modes at the input of the rectangular waveguide via an input diagonal-horn antenna. A second photo-mixer is used, together with a silicon mirror Fresnel scatterer, to act as a polarization-sensitive coherent detector to characterize the emitted field. We find that the radiated field, excited by the fundamental waveguide mode, is characterized by a linear polarization. In addition, we find that the polarization of the radiated field rotates by 45 degree if selectively exciting higher-order modes in the waveguide. Despite the higher-order modes, the radiated field appears to maintain a predominant Gaussian beam character, since an unidirectional coupling to a detector was possible, whereas the unidirectionality is independent of the frequency. We discuss a possible application of this finding.
