Nanoporous artificial materials: confining the THz excited surface plasmon polariton

在电磁光谱中，可以在可见光和微波之间发现太赫兹光。它相对未被开发，因为在这一地区制造紧凑、强大的资源特别困难。此外，它还面临着生产高效(即低损耗)器件来引导和操纵太赫兹光的材料短缺的问题。然而，这是一个有趣的区域，因为它在能量上类似于许多生物过程，所以我们可以研究蛋白质的行为和DNA。它能够激发分子内的振动，这意味着可以很容易地识别毒品和爆炸物。这项建议建立在我们在设计和开发所谓人造材料方面的专业知识的基础上。人造材料具有经过工程设计的电磁特性。这意味着我们可以控制太赫兹光与材料相互作用时发生的事情。定制电磁特性的典型方法包括将小的(亚波长)特征结合到容易获得的材料(例如，金和铜等金属)中和在其上。在这里，我们将生产人造材料，当太赫兹光照射材料表面时，这种材料能够产生一种特殊类型的波。这种特殊类型的波或电荷振荡被称为表面等离子体激元(SPP)，其性质高度依赖于与表面接触的材料的类型。这使得它适合于对各种材料进行传感，具有极好的选择性。这种方法将使我们能够在非常短的(皮秒)时间范围内监控活动和变化。不幸的是，当被太赫兹光激发时，这种波从表面延伸了一段距离。这使得它对表面的事件(例如，生物分子附着)不那么敏感。这项研究的目的是通过在我们现有的人造材料设计(基于带有微孔阵列的铜箔)中引入纳米孔层来改善SPP的限制。该团队包括微制造工程师和物理学家，他们将共同设计、制造和测试材料。

Terahertz light can be found between visible light and microwaves in the electromagnetic spectrum. It is relatively unexploited because compact, powerful sources have been particularly difficult to make in this region. Furthermore, it suffers from a shortage of materials which produce efficient (i.e. low loss) devices to guide and manipulate the terahertz light. It is, however, an interesting region because it is energetically similar to many biological processes, so we can study protein behaviour and DNA. It is able to excite intramolecular vibrations which means that drugs and explosives can be readily identified. This proposal builds on our expertise in the design and development of so-called artificial materials. An artificial material has electromagnetic properties which have been engineered. This means that we can control what happens when the terahertz light interacts with the material. A typical approach to tailor the electromagnetic properties involves incorporating small (sub-wavelength) features into and on readily available materials (e.g. metals such as gold and copper). Here we will produce artificial materials which are capable of producing a special type of wave when the terahertz light illuminates the material's surface. This special type of wave, or oscillation of charge, is known as a surface plasmon polariton (SPP), and its properties are highly dependent on the type of material that is in contact with the surface. This makes it suitable for sensing a wide variety of materials with excellent selectivity. The approach will enable us to monitor activity and changes on a very short (picosecond) timescale. Unfortunately, when excited by terahertz light, this wave extends some distance from the surface. This makes it less sensitive to events at the surface (e.g. biomolecules attaching). The aim of this research is improve the confinement of the SPP by introducing a nanoporous layer to our existing artificial material designs (based on copper foils with arrays of microscale apertures). The team includes microfabrication engineers and physicists who will work together to design, fabricate and test the materials.