设计出一种结构新颖的宽波段太赫兹偏振分束器, 这种偏振分束器由夹层式亚波长金属光栅制成。亚波长金属光栅偏振分束器可以将入射的任意自然光分成两束偏振状态垂直的线偏振光。其中, TE模反射而TM模透射。设计的偏振分束器在3.5~5.5 THz波段可以达到很高的衍射效率与消光比。但是, 在光栅的实际制作过程中, 加工技术的缺陷引起的误差大大影响了光栅的性能, 比如衍射效率, 消光比等。因此文中对一些结构参数进行了计算, 从计算结果可以看出这种偏振分束器也有很好的工艺容差。当覆盖层厚度D1与底层介质厚度D3的变化范围分别为1~1.2 滋m和 2.8~3 滋m时, T■■大于96.9%, R■■大于98.7%。Tc和Rc分别大于31 dB和33.4 dB。结果显示, 设计的偏振分束器在2 THz的带宽10°的大角度范围内, 衍射效率高于90%, 消光比大于20 dB。因此文中设计对于太赫兹调制器件的研究, 以及太赫兹通信系统的集成都有很大的参考价值。

A broadband terahertz (THz) polarization beam splitter (PBS) was proposed. The PBS was based on subwavelength grating sandwiched between silica layers, which could split an arbitrarily polarized optical beam into two orthogonal, linearly polarized components, and then reflected the TE mode and transmit the TM mode. It was shown that THz PBS could efficiently operate from 3.5 THz to 5.5 THz, with high diffraction efficiencies and extinction ratios. In the process of PBS manufacture, there would be unavoidable deviations of the geometric parameters, which may affect its properties, i.e. the diffraction efficiencies and extinction ratios. Therefore, some structure parameters were calculated. Those values suggested that the designed PBS allows sufficient manufacture tolerances. When D1 ranged from 1 滋m to 1.2 滋m and thickness D3 ranged from 2.8 滋m to 3 滋m, the values of T■■ are always more than 96.9% and those of R■■ are more than 98.7%. And the values of Tc and Rc were respectively kept higher than 31 dB and 33.4 dB. These results show the PBS with a frequency bandwidth of 2 THz, a large angle range of 10°, an extinction ratios over 20 dB and a diffraction efficiencies over 90%, is obtained. This work may inspire related studies and achieve some potential applications in THz manipulation system.