【作者】 赵西宁；

【导师】 张晓萍；

【作者基本信息】 兰州大学 ， 无线电物理， 2013， 硕士

【摘要】 随着科学技术的迅猛发展,各项工艺技术都在向着微型精细的领域发展。尤其是对于高端纳米光学技术应用,如光集成器件、光学成像、光刻、光学信息存储、生物传感等领域,常常需要纳米量级的光学器件。然而,由于衍射极限的存在,限制了传统光学技术的进一步发展。因此,如何在纳米量级上实现光操控和突破衍射极限成为重要的研究方向。首先,基于零折射光子晶体研究分析,提出了一种工作在光学频段的光子晶体移相器。零折射率材料意味着光处于一种准无限大相速度和无限长波长状态,因此,当平面波从自由空间入射到零折射率材料区域,波在通过零折射率材料区域时就像这个区域不存在一样,离开零折射率材料区域时波的形态完全取决于入射时的形态,利用这个性质,将两个完全相同的零折射率光子晶体结构级联,通过调节两个光子晶体结构之间的距离,可以线性的改变入射波的相位。与此前复杂的电压调整相移器不同,这种相移器仅仅通过调整距离就可以十分方便的实现相移,与温度、电压、功率等无关,并且损耗极低,同时工作频率也与传统的相移器相比有了极大的提高,这在光集成电路中有着十分重要的作用。其次,基于表面等离子体激元,我们又自行设计了一种对称金属双缝介质光栅聚焦透镜模型,实现双向聚焦。接下来,我们通过改变光源与透镜之间距离,研究了距离对聚焦效果的影响。我们发现这种透镜模型的最优聚焦点每隔半个波长出现一次,在距离透镜501nm时,聚焦能量峰值达到1215,焦距达到2.67um,呈现出十分优异的聚焦特性,这对以后聚焦模型的设计与应用有重要的价值。最后,克服现有的聚焦透镜结构对入射波波长的依赖,我们又设计出一种对称金属双缝梯形介质光栅聚焦透镜模型,在入射波波长561nm到590nm范围内,以1nm为步长,仿真结果显示,聚焦点能量峰值从3缓慢下降到2.1,焦斑半径从438.5nm降低到347.7nm,焦距从2.4um下降到2.34um,也就是说在分辨率有所提高的情况下,聚焦能量并没有显著的降低,聚焦效果保持相对稳定,这在实际光子器件中有重要的应用前景。更多还原

【Abstract】 The steadily decreasing dimensions in semiconductor devices are for filling the rapid development of the scientific technology, especially for the high-end nano-optical imaging technology. Nano-optical devices are widely required in many fields, such as optical integrated circuit, optical imaging, optical lithography, high-density optical storage, bio-sensor, etc. However, traditional optical techniques have been blocked for the diffraction limit. Therefore, nanoscale optical manipulation and breaking the diffraction limit to become an important research direction.Firstly, based on the analysis of zero-refractive-index PCs, we present a novel phase-shifter. A refractive index of zero implies that light enters a state of quasi-infinite phase velocity and infinite wavelength. Thus, a plane wave incident from the left air region can pass through the zero-refractive-index metamaterials (ZRIM) as if it were not there and the shape of the wavefronts leaving the ZRIM depends solely on the shape of the exit surfaces of the ZRIM, which provides high flexibility in the design of phase patterns. By the way of reasonably adjusting the distance between the ZRIMs, the wave phase on the right side of the second ZRIM can be changed linearly compared to the incident wave phase. This structure can decrease the loss and avoid the effect of operation voltage fluctuation. It can be easily nanofabricated within current silicon foundries, suggesting significant potential for the development of future electronic-photonic integrated circuits.Following, Based on SPPs, beam optical focusing structures capable of double side beam focusing are proposed. The relationships between focal intensity, focal length, focal width and the distance from optical source to lens structure are investigated and numerically simulated. We found that the optimal focusing point of this lens model appears at a period of half wavelength. When the distance became501nm, the focused energy peak reached1215and focal length was2.67um. These excellent focusing characteristics are of great value for the focusing model design and application.Finally, a beam optical focusing structure with double subwavelength metal slits surrounded by tapered surface trapezoid dielectric gratings (DTDG) is proposed. By increasing the incident wavelength from560nm to591nm at a step of1nm, the focal length decreases monotonously from2.4um to2.34um, and the focal length maintains constant in the wavelength domain. The FWHM of focal width and peak intensity decrease monotonously from438.5nm to347.7nm and3to2.1respectively as well. Above all, it maintains constant for a large wavelength domain (560nm-591nm), which is a great potential for integrated optics, biomedicine sensing, nanophotonics, optical measurement and related applications.更多还原