Semiconducting and superconducting nano-devices to control terahertz radiation: emitters, filters, detectors, amplifiers and lenses.

几乎所有的电磁辐射都被人类大量使用。然而，有一种具有一个频率范围的辐射仍然没有使用。这就是所谓的太赫兹(THz)范围，与此相关的问题称为太赫兹间隙。近年来，人们对太赫兹科学技术的兴趣与日俱增，这是因为它在物理、天文学、化学、生物和医学中的许多重要应用，包括太赫兹成像、光谱学、层析成像、医疗诊断、健康监测、环境控制以及化学和生物识别。太赫兹带隙很难通过电子或光学设备来弥合，它覆盖了生物过程的温度，以及由于红移而产生的大爆炸剩余光度的很大一部分落入了太赫兹带隙。这个问题的存在是因为没有实际的频率在太赫兹范围内的电磁辐射源、过滤器或接收器。为什么太赫兹辐射(T射线)如此重要？T射线可以穿透身体，但与X光不同，它不会留下任何损害。T射线的穿透和吸收光谱与频率和材料有关。在几个太赫兹的频率范围内，水溶液的穿透深度非常有限，而塑料材料实际上是透明的。如果产生可调谐的强大辐射源和接收器，一切都可以被连续扫描。这将开启医学(癌症和其他疾病可以在非常早期阶段被发现和消除)和反恐战争的新阶段。基于纳米结构的太赫兹电子学可能在超高带宽无线通信网络、车辆控制、大气污染监测、卫星间通信和光谱学等方面有许多有前途的应用。我们预计，我们的提议将是消除太赫兹技术差距的重要一步。我们的研究重点是基于超材料和半导体超晶格(M-SSL)和具有空间调制特性的层状超导体(LSC)的太赫兹发射器、滤波器、探测器、透镜和放大器。该激光器可用作太赫兹辐射(T-射线)的发生器。这是建立在布洛赫振荡现象的基础上的，这种现象现在已经在许多关于SSL的实验中观察到了。最重要的是，这种电子振荡的频率属于太赫兹范围。超材料超晶格(MSL)代表了John Pendry等人最近发现的一种新的物质形式，Veselago预计，在这种物质中，可以控制、产生和捕获非常宽光谱的电磁辐射。我们的初步估计表明，折射率和渗透率为负的超材料是用于太赫兹器件的理想材料。此外，约瑟夫森涡在LSC中的运动也可能产生T射线。在一种更简单的形式中，当约瑟夫森涡旋的速度超过超导体中的太赫兹光速时，就会产生T射线。这将是简单的切伦科夫辐射。因此，我们建议利用M-SSL和LSC中存在的非线性和量子效应来构建用于THz辐射的各种器件，如THz发射器、滤光器、探测器、透镜和放大器。第一个想法是利用SSL的独特特性，将千兆赫频率的微波转换成太赫兹频率的辐射，反之亦然。我们建议将固体激光器放入微波谐振器中，并研究这种器件作为太赫兹辐射源的可能性。在第二个想法中，我们将设计超材料(MSL)来捕获、检测和控制太赫兹辐射。在第三个想法中，我们将使用LSC，它由被非常薄的绝缘层隔开的薄超导层组成。有天然的LSC，如高温超导体(HTSC)，或者它们可以由超导和绝缘材料人工制成，如SSL。LSC工程有一个完整的领域

Practically all electromagnetic radiation is heavily used by humankind. However there is a radiation with one range of frequencies which is still not used. This is so-called terahertz (THz) range and the associated problem is called the terahertz gap. The recent growing interest in THz science and technology is due to its many important applications in physics, astronomy, chemistry, biology and medicine, including THz imaging, spectroscopy, tomography, medical diagnosis, health monitoring, environmental control, as well as chemical and biological identification. The THz gap is difficult to bridge by either electronic or optical devices and it covers temperatures of biological processes and a substantial fraction of the luminosity remnant from the Big Bang due to the red shift falls into the THz gap. The problem exists because there are no practical sources, filters or receivers of electromagnetic radiation with frequencies in the THz range. Why is THz radiation (T rays) so important? T- rays may penetrate bodies but, in contrast with X-rays, leave no damage. The spectrum of T-rays penetration and absorption is frequency and material dependent. In a frequency range of a few THz the penetration depths through aqueous solutions is very limited, while plastic materials are practically transparent. If tunable and powerful sources and receivers of such radiation are produced everything can be scanned continuously. This would then initiate a new stage in medicine (cancer and other diseases could be detected and removed at a very early stage) and in the war against terrorism. Nanostructure-based THz-electronics may give many promising applications, ie in ultra-high bandwidth wireless communication networks, vehicle control, atmospheric pollution monitoring, inter-satellite communication and spectroscopy, to name a few. We anticipate that our proposal will be an important step in removing the technological Terahertz gap''.The focus of our research are THz emitters, filters, detectors, lenses and amplifiers based on metamaterial and semiconductor superlattices (M-SSL) and layered superconductors (LSC) with spatially modulated properties. The SSL can be used as a generator of THz radiation (T-rays). This is based on the phenomenon of Bloch oscillations, which have now been observed in many experiments with SSL. Most importantly the frequency of such electronic oscillations belongs to the THz range. Metamaterial superlattices (MSL) represent a new form of matter discovered recently by John Pendry et al and anticipated by Veselago where electromagnetic radiation of a very broad spectrum may be controlled, generated and trapped. Our preliminary estimations indicate that metamaterials where refractive index and permeability are negative are ideal to be used in the THz devices. Moreover the motion of Josephson vortices in the LSC may also generate T-rays. In a more simple form T-rays arise, when the speed of the Josephson vortices exceeds the THz light speed in superconductors. This will be simply Cherenkov radiation.Thus we propose to build various devices for the use of THz radiation such as THz emitters, filters, detectors, lenses and amplifiers using nonlinear and quantum effects existing in M-SSL and LSC. The first idea is to use unique properties of SSL as a transformer of the microwaves with gigahertz frequencies into radiation with THz frequency and vice versa. We propose to put SSL in a microwave resonator and investigate such a device as a possible source for THz radiation. In the second idea we will design metamaterials(MSL) to trap, to detect and to control THz radiation. In the third idea we will use the LSC which consists of thin superconducting layers separated by very thin insulating layers. There are natural LSC, such as, high temperature superconductors (HTSC) or they can be made artificially from superconducting and insulating materials, like SSL. There is a whole area of LSC engineering