复合金属人工微结构双带偏振滤波器设计与研究

发布时间：2018-05-01 11:17

本文选题：复合金属人工微结构 + 表面等离子体　；参考：《福建师范大学》2015年硕士论文

【摘要】：随着信息时代的到来,需要处理的信息容量在不断增长,如何更快速的处理海量信息显得尤为重要。现代的信息处理技术以集成电路为载体,其速度取决于电子回路的集成度,但是芯片的进一步集成,将引起不可避免的量子化效应,导致更进一步的信息处理技术发展遇到瓶颈。因此,利用光集成芯片来代替电子集成芯片作为信息的载体,可望更进一步的解决信息高速传输的问题。但是,光集成电路受到衍射极限的限制,其集成程度被局限在了光波长量级,还达不到跟电子回路一样高的微型化。超材料,也即亚波长人工复合金属结构,它可以通过激发表面等离激元,来实现各种奇异的电磁现象,比如负折射、超强透射和完美吸收等。基于超材料的光子器件可以通过控制其表面等离子波来实现信息的调制和传输。其在亚波长尺度上灵活调制和传输电磁波的能力,使得基于超材料的光子器件有望打破衍射极限,从而使得器件具有集成度高、结构紧凑等优点,为制作与现有电子芯片连接的光子芯片提供了可能。这对解决芯片微型化而引起的量子化效应具有重要意义。在本论文中,基于电磁波计算仿真的有限时域差分方法,我们设计了两种复合金属人工微结构,此超材料结构在满足完美吸收的基础上设计了两类反射型的双带偏振滤波器件,具体的研究成果和工作如下：1.设计分析了一个并列式非对称双十字复合金属结构的双带可调偏振滤波器。结果显示在两个偏振方向上,各有两个不同的共振吸收波长。进一步的研究分析表明：滤波器的共振吸收波长与平行于偏振方向的金属条长度有关,与垂直于偏振方向的金属条长度无关。因此,可以通过改变相应的金属条长度来实现对滤波器的滤波波长自由调节。另外,从计算的结果可以看出,滤波器在两个偏振方向共四个滤波工作波长的反射率都接近于零,这说明滤波器具有很好的滤波效果。2.设计分析了一个嵌套式非对称双十字复合金属结构的双带可调偏振滤波器。因为吸收波长只决定于和入射光偏振平行的金属条,因此可在非对称十字型金属结构周期性阵列中,嵌套一个不同尺寸大小的非对称十字型金属结构周期阵列,设计出一个新的双带可调的滤波器结构。结果显示在两个偏振方向上,各有两个不同的共振吸收波长,并且此滤波器同样可以通过改变相应偏振方向的矩形条长度来实现对滤波波长的自由调节。因为是嵌套结构,所以器件更紧凑、尺寸更小。本文创新点：利用基于表面等离激元的超材料对电磁波具有完美吸收的特性,提出并设计了两种不同结构的双带偏振可调滤波器,实现了分别在Ex和Ey偏振方向上同时对两个不同波长光的共振吸收。这两种双带偏振可调滤波器尺寸紧凑、工作波长自由调谐、制作工艺简单,因此可以用在未来的光集成芯片中。
[Abstract]:With the arrival of the information age, the information capacity that needs to be dealt with is growing, how to deal with the mass of information more quickly is particularly important. The speed of modern information processing technology depends on the integration of electronic circuits, but the further integration of chips will lead to the inevitable quantization effect. Leading to further information processing technology development encountered bottlenecks. Therefore, the use of optical integrated chips to replace electronic integrated chips as a carrier of information is expected to further solve the problem of high-speed information transmission. However, the optical integrated circuit is limited by the diffraction limit, and its integration degree is limited to the order of light wave length, which is not as high as the miniaturization of the electronic circuit. Metamaterials, that is, subwavelength artificial composite metal structures, can realize all kinds of strange electromagnetic phenomena, such as negative refraction, super strong transmission and perfect absorption, by exciting surface isoexcitations. Photonic devices based on metamaterials can modulate and transmit information by controlling their surface plasma waves. Its ability to modulate and transmit electromagnetic wave flexibly at sub-wavelength scale makes it possible to break the diffraction limit of photonic devices based on metamaterials, which makes the devices have the advantages of high integration and compact structure. It is possible to fabricate photonic chips connected to existing electronic chips. This is of great significance to solve the quantization effect caused by chip miniaturization. In this thesis, two kinds of composite metal artificial microstructures are designed based on the finite difference time-domain (FDTD) method of electromagnetic wave simulation. Two kinds of reflective dual-band polarization filters are designed on the basis of perfect absorption. The concrete research results and work are as follows: 1. A dual band tunable polarization filter with a parallel asymmetric double cross composite metal structure is designed and analyzed. The results show that there are two different resonant absorption wavelengths in two polarization directions. Further analysis shows that the resonant absorption wavelength of the filter is related to the length of the metal strip parallel to the polarization direction and independent of the length of the metal strip perpendicular to the polarization direction. Therefore, the filter wavelength can be adjusted freely by changing the length of the metal strip. In addition, it can be seen from the calculation results that the reflectivity of four filter wavelengths in two polarization directions is close to zero, which shows that the filter has a good filtering effect. 2. A double band tunable polarization filter with a nested asymmetric double cross composite metal structure is designed and analyzed. Because the absorption wavelength is determined only by the metal strip parallel to the polarization of the incident light, it is possible to nest an asymmetric cross-metal periodic array of different sizes in a periodic array of asymmetric cross metal structures. A new dual band tunable filter structure is designed. The results show that there are two different resonant absorption wavelengths in each polarization direction, and the filter can adjust the filter wavelength freely by changing the length of the rectangular strip in the corresponding polarization direction. Because of the nested structure, the device is more compact and smaller. In this paper, two kinds of dual-band polarization tunable filters with different structures are proposed and designed. The resonant absorption of two different wavelengths of light in the polarization direction of Ex and Ey is realized respectively. These two kinds of dual-band polarization tunable filters are compact in size, freely tunable in operating wavelength and simple in fabrication process, so they can be used in future optical integrated chips.
【学位授予单位】：福建师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN713

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