Polarization control is shown to enhance functionalities of terahertz waves in various applications. As a step toward introducing efficient practical devices operating in the terahertz band, we propose and experimentally validate a free-standing three-layer polarization converter operating in transmission. The device can efficiently convert a linearly polarized terahertz wave to its orthogonal counterpart. Our device comprises split-ring and H-shaped resonators inserted between two layers of orthogonal wire gratings. The sole dielectric material is a cyclic olefin copolymer (COC) that has exceptionally low-loss to terahertz waves. The measurement demonstrates a conversion efficiency of >80%, over 0.2–1.0 THz, giving an ultra-wide bandwidth of 133%. The wide bandwidth is attributed to multiple resonances of the two resonators in a unit cell. Importantly, an unconventional fabrication process yields a multi-layer low-loss COC that leads to high efficiency. The proposed design can also be tailored for practical applications across the electromagnetic spectrum.

中文翻译：

---

太赫兹波的超宽带三层透射线性偏振转换器

偏振控制显示出可以增强各种应用中太赫兹波的功能。作为引入工作在太赫兹频段的高效实用设备的一步，我们提出并通过实验验证了在传输中工作的独立式三层偏振转换器。该设备可以有效地将线性极化的太赫兹波转换为其正交的太赫兹波。我们的设备包括插入两层正交线栅之间的开口环和H形谐振器。唯一的介电材料是对太赫兹波具有极低损耗的环状烯烃共聚物（COC）。测量结果表明，在0.2–1.0 THz的范围内，转换效率> 80％，超宽带宽为133％。宽带宽归因于单位单元中两个谐振器的多次谐振。重要的是，非常规制造工艺会产生多层低损耗COC，从而提高效率。建议的设计还可以针对电磁频谱的实际应用进行定制。