THz near-field spectroscopic visualization of metal-hole array

在这个项目中，我们提出并开发了一种新的技术，使金属孔阵列的太赫兹(THz：0.1-10 GHz)近场光谱可视化成为可能。其中自外差技术和无极化电光探测技术是关键。利用光频移器对产生的光拍频进行移频，实现太赫兹自外差探测。待检测的太赫兹信号在光纤安装的电光晶体(ZnTe)中通过电光相位调制一次被上变频，然后通过产生的边带的相干检测被下变频到中频带。与传统的极化电光探测相比，我们的相干技术不仅大大提高了测量的稳定性和重复性，而且测量的简单性也得到了显著的提高。首次证明了金属孔阵中自由传播的连续太赫兹波(125 GHz)和近场的位相演化。

In this project, we proposed and developed a new technique which enables terahertz (THz: 0.1-10 GHz) near-field spectroscopic visualization of metal-hole array. The self-heterodyne technique and nonpolarimetric electrooptic (EO) detection technique are the key. The frequency of the optical beat for the generation is shifted by an optical frequency shifter to realize THz self-heterodyne detection. The THz signal to be detected is once up-converted by the EO phase modulation in the fiber-mounted EO crystal (ZnTe), then down converted to the intermediate frequency band by the coherent detection of the generated sideband. Our coherent technique significantly improved not only the stability and the repeatability but also the simplicity of the measurements compared with the conventional polarimetric EO detection. As a result, phase evolution of the freely propagating continuous THz wave (125 GHz) and near-field of a metal-hole array have been demonstrated, for the first time.