中红外宽带等离子体超材料电磁吸收器的研究

发布时间：2018-05-17 07:03

  本文选题：等离子体超材料 + 电磁吸收器　； 参考：《深圳大学》2015年硕士论文

【摘要】：等离子体超材料是一种具有金属-电介质微纳结构的人工电磁材料,具有自然材料难以获得的特异电磁性质。近十年来,等离子体超材料在科研界引起了的广泛兴趣以及进行了大量的研究。在等离子体超材料众多的应用中,其中一个重要的领域就是超材料电磁吸收器。早期的吸收器依赖于材料本身的吸收特性,不可避免地导致了体积庞大,吸收效率低的缺点。等离子体超材料则是基于金属纳米结构激发等离子体共振对入射光进行完美吸收(100%吸收率)。这种吸收器具有深度亚波长尺度,完美吸收以及谐振频率可调等一系列优点,在诸如热辐射发射器,传感器,太阳能电池等方面有着广泛的潜在应用。本论文围绕中红外宽带等离子体吸收器的研究与设计,主要工作总结如下:(1)提出并设计了一种工作在中红外波段的超紧凑光栅型多频带等离子体超材料吸收器。这种吸收器具有异常紧凑的结构特性,能够利用小尺寸结构单元实现对较长红外波进行吸收。此外,当相邻单元间距减小时,由于各相邻单元间的相互耦合,整体吸收谱会产生红移现象,进一步使得结构小型化成为可能。这种吸收器也是目前为止同类中红外超材料吸收器中最为紧凑的一种结构。本论文同时采用了等效LC模型系统地分析并解释其物理机制。作为例子,提出并设计了一个单元周期为Λ=3.34μm的四波段吸收器,吸收谱中四个吸收峰的波长依次为6.9μm,7.9μm,8.9μm和9.97μm,吸收效率分别为99.9%,99.2%,96.1%和87.4%。(2)提出并设计了一种多腔阵列型的宽带中红外等离子体超材料吸收器,具有高效扩展吸收带宽的同时保持了吸收器结构紧凑厚度薄的特点。提出了一种“之”字形的设计方法避免相邻谐振腔之间的耦合导致的带宽减小。同时分别设计了两层和三层结构的吸收器,中心带宽8.1μm,半峰全宽分别为25%和48%,并且吸收特性不依赖于角度变化。这种结构同时能够扩展到其他如太赫兹以及微波波段。(3)提出了一种工作在红外波段的基于石墨烯负载的具有十字裂缝结构的用于宽频光调制的超材料可调吸收器。石墨烯-光耦合作用由于裂缝结构中产生的耦合磁共振显著增强,从而克服石墨烯在中红外的泡利阻塞效应,实现了吸收峰大范围调制的调制器。数值仿真表明,在费米能级为0.6eV的情况下,两个谐峰的调制范围均在其原始谐振波长的20.1%和25.5%,远大于之前的一些工作。同时采用了石墨烯等效电感模型分析了石墨烯调制的物理机制以及与调制宽度超材料几何结构之间的关系。这种器件在生物探测,光通信以及成像等领域有着极为广泛的应用。
[Abstract]:Plasma supermaterial is a kind of artificial electromagnetic material with metal-dielectric micro-nano structure, which has special electromagnetic properties which are difficult to obtain from natural materials. In the last ten years, plasma metamaterials have attracted wide interest and carried out a lot of research in the field of scientific research. In many applications of plasma supermaterial, one of the most important fields is supermaterial electromagnetic absorber. The early absorbers depend on the absorption characteristics of the material itself, which inevitably lead to the disadvantages of large volume and low absorption efficiency. The plasma supermaterial is based on metal nanostructure excited plasmon resonance to perfectly absorb the incident light with 100% absorptivity. This kind of absorber has a series of advantages, such as deep subwavelength scale, perfect absorption and adjustable resonant frequency, etc. It has a wide range of potential applications in such fields as thermal radiation emitter, sensor, solar cell and so on. This thesis focuses on the research and design of the mid-infrared broadband plasma absorber. The main work is summarized as follows: 1) A super-compact grating type multi-band plasma superabsorber working in the mid-infrared band is proposed and designed. This kind of absorber has very compact structure and can absorb long infrared wave by using small size structure element. In addition, when the distance between adjacent elements is reduced, the whole absorption spectrum will be red-shifted due to the coupling between adjacent elements, which makes it possible for the structure to be miniaturized. This kind of absorber is also the most compact structure in the same kind of mid-infrared supermaterial absorber so far. At the same time, the physical mechanism is analyzed and explained systematically by using the equivalent LC model. As an example, a four-band absorber with a unit period of 3. 34 渭 m is proposed and designed. The wavelengths of the four absorption peaks in the absorption spectrum are 6.9 渭 m, 7.9 渭 m, 8.9 渭 m and 9.97 渭 m, respectively. The absorption efficiency is 99.9% and 99.2% and 87.4%, respectively. A multi-cavity array broadband mid-infrared plasma supermaterial absorber is proposed and designed. It has the characteristic of expanding the absorption bandwidth efficiently and keeping the structure of absorber compact and thin. A "zigzag" design method is proposed to avoid bandwidth reduction caused by coupling between adjacent resonators. At the same time, two-layer and three-layer absorbers are designed. The center bandwidth is 8.1 渭 m, the full half-width is 25% and 48% respectively, and the absorption characteristics are independent of the angle variation. This structure can also be extended to other structures such as terahertz and microwave-band. A kind of metamaterial tunable absorber with graphene supported graphene based on infrared band for wide-band optical modulation is proposed. The coupling magnetic resonance (Mr) produced by the crack structure is significantly enhanced in graphene optical coupling cooperation, which overcomes the Pauli blocking effect of graphene in the mid-infrared region and realizes a modulator with a large range of absorption peaks. Numerical simulation shows that when Fermi level is 0.6eV, the modulation ranges of the two harmonic peaks are both 20.1% and 25.5% of the original resonant wavelength, which is much larger than some previous work. At the same time, the physical mechanism of graphene modulation and the relationship between the modulation width and the geometric structure of the supermaterial are analyzed by using the graphene equivalent inductance model. This device has been widely used in biological detection, optical communication and imaging.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34;O441.6
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本文编号：1900409