基于微纳薄膜界面模式的光吸收效应研究

发布时间：2018-04-12 00:29

本文选题：硅薄膜 + 钙薄膜　；参考：《河南师范大学》2017年硕士论文

【摘要】：光的传输特性一直都是人们普遍关心的一个物理现象,随着人们研究的深入,人们可以通过不同的光子人工微结构对光的传输进行操控,其中,光子晶体作为一种由不同折射率材料组成的周期性人工微结构,在概念被提出后就引起了人们广泛的关注。光子晶体作为增强光吸收的一种陷光结构,是增强光吸收的有效方法之一。自表面等离激元提出以来,科学家们运用了各种新型光子器件来激发表面等离激元。随着光学器件研究的发展,人们更加关注突破衍射极限的表面等离激元的研究。本文提出并通过数值仿真证明了硅基微纳结构薄膜在给定吸收层厚度的情况下,能够在可见光范围内显著提高全向光吸收,并从理论上探讨了钙薄膜在Kretschmann激发下的等离激元特性,通过计算发现,具有等离激元特性的钙薄膜可用作Fraunhofer波长窄带滤波器。论文的第二章对本文中用的理论研究方法进行了阐述,其中重点讲述了通过平面波展开法对光子晶体的计算和严格耦合波法。论文的第三章提出了一种由硅基光子晶体与金属复合微纳结构薄膜,并通过数值仿真证明了在给定吸收层厚度的情况下,硅基微纳结构薄膜能够在可见光范围内显著提高全向的光吸收。与完整的硅/金属复合薄膜进行比较研究发现,在硅薄膜厚度相同的条件下,硅基微纳结构薄膜能够使吸收率提高近70%。此外,通过分析发现这种硅基微结构具有全向的完全带隙,能够在较宽的空间频谱范围提供合适的反射相移,使得硅基微纳结构薄膜的增强吸收效应在入射角高达60°的情况下依然可行。为了进一步研究硅基微纳结构的性质,本文利用平面波展开法计算硅基微纳结构薄膜的能带结构通过对相应结构的能带以及相应模式场构型分析可以了解,这种对入射角度变化不敏感的光吸收增强效应可以归因于,金属平板与截断的光子晶体中特殊的边界陷光效应和六角晶格的全向带隙。在论文的第四章,本文从理论上探讨了碱金属钙质薄膜在Kretschmann激发下的等离子激元特性。基于表面等离子激元,钙质薄膜对p偏振光的吸光率吸收可达100%,远远高于其在422.7nm的波长处区(对应于Fraunhofer g线)对s偏振光的吸光率吸收。在422.7nm的波长下,45nm厚钙质薄膜对s偏振光的反射率约为76%,当入射角为19?时,对p偏振光的反射率达到最小值。由于该基于钙质薄膜的窄带滤波器为体积庞大的固态器件,尤其适合于平面内集成,与传统的钙原子滤波器搭配使用效果更好。此外,基于钙质薄膜的等离子体滤波器在具有角度灵敏度和偏振灵敏度的传感器以及弱激光检测领域具有应用前景。
[Abstract]:The transmission characteristics of light have always been a physical phenomenon of general concern. With the development of research, people can manipulate the transmission of light through different photons artificial microstructures, among which,As a periodic artificial structure composed of different refractive index materials, photonic crystals have attracted much attention since the concept was proposed.Photonic crystals, as a trapping structure of enhanced light absorption, are one of the effective methods to enhance light absorption.Since the introduction of surface isoexcitators, scientists have used a variety of new photonic devices to excite surface isoexcitators.With the development of optical devices, more attention has been paid to the study of surface isopherons that break through the diffraction limit.In this paper, the numerical simulation results show that the Si-based thin films can increase the omnidirectional optical absorption significantly in the visible range under the given absorption layer thickness.The characteristics of Kretschmann excited calcium thin films are discussed theoretically. It is found that the calcium thin films with the characteristics of isophosphors can be used as narrow band filters for Fraunhofer wavelength.In the second chapter, the theoretical methods used in this paper are described, in which the calculation of photonic crystals by plane wave expansion method and the strictly coupled wave method are emphasized.In the third chapter of the thesis, a kind of thin film with silicon based photonic crystal and metal composite microstructures is proposed, and it is proved by numerical simulation that the thickness of absorption layer is given.Silicon-based micro-nano-structure films can significantly improve the omnidirectional optical absorption in the visible range.Compared with the complete silicon / metal composite film, it is found that the absorption rate can be increased by nearly 70% under the condition of the same thickness of silicon film.In addition, it is found that the Si-based microstructures have omnidirectional complete bandgap, which can provide a suitable reflection phase shift in a wide spatial spectrum range.The enhanced absorption effect of Si-based thin films is still feasible when the incident angle is as high as 60 掳.In order to further study the properties of silicon based micro / nano structure, the energy band structure of silicon based micro / nano structure thin films can be calculated by using plane wave expansion method through the analysis of the corresponding structure's energy band and the corresponding mode field configuration.This enhancement effect, which is insensitive to the change of incident angle, can be attributed to the special boundary trapping effect in the metal plate and the truncated photonic crystal and the omnidirectional band gap of the hexagonal lattice.In the fourth chapter, the plasma excitations of alkaline calcium films excited by Kretschmann are discussed theoretically.Based on the surface plasma exciton, the absorption rate of p-polarized light of calcium thin film can reach 100%, which is much higher than the absorption rate of S-polarized light in the wavelength region of 422.7nm (corresponding to Fraunhofer g line).At the wavelength of 422.7nm, the reflectivity of 45nm thick calcareous thin film to S-polarized light is about 76, when the incident angle is 19?The reflectivity of p-polarized light reaches the minimum value.Because the narrow band filter based on calcium thin film is a solid state device with large volume, it is especially suitable for in-plane integration, and the effect is better in combination with the traditional calcium atom filter.In addition, plasma filters based on calcium thin films have promising applications in sensor with angular sensitivity and polarization sensitivity, as well as in the field of weak laser detection.
【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN713;O734

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