QQ客服 官方微博 反馈留言

题名	近场超分辨光盘中微纳结构的远场和近场光学性质分析
作者	瞿青玲
学位类别	博士
答辩日期	2004
授予单位	中国科学院上海光学精密机械研究所
导师	干福熹
关键词	超分辨近场结构 微纳结构 高斯衍射模型 时域有限差分法 信噪比
其他题名	Far-field/near-field optical Properties of micro-/nano- structures in super-resolution near-field structure disk
中文摘要	本论文共分为引言、文献综述、计算方法与原理、远场光学数值模拟与分析、近场光学数值模拟与分析和结论六大部分。 引言部分阐明了本课题的研究目的主要是利用数值计算工具研究超分辨近场结构光盘中微纳结构的远场和近场光学特性，分析超分辨近场结构光盘产生超分辨的机理，为掩膜材料的选择提供理论依据。 文献综述部分详细地叙述了近场光存储技术的发展历程、研究现状及发展趋势，重点描述了超分辨近场结构技术的研究背景、工作原理、应用前景及国内外的研究进展，指出超高密度、超大容量、超快存取是光存储技术的发展方向，目前各种超高密度光存储技术的研究开发都是围绕这一目标而进行的，而集近场光学和超分辨技术优点于一身的超分辨近场结构技术是目前最具实用化前景的超高密度光存储技术之一。但对其超分辨机理的认识还不充分。 计算方法与原理部分分别对远场光学理论分析工具和近场光学理论分析工具进行了简单的介绍。远场的分析主要采用Z-扫描衍射理论，这一理论主要是在菲涅尔-基尔霍夫衍射理论基础上建立起来的。该理论将非线性介质看作是一个相位调制的衍射屏，该衍射屏会对高斯光束产生衍射，用菲涅尔-基尔霍夫衍射积分公式可以求出远场接收屏上的光强分布，进而可以求出透过率等物理量。与Z-扫描的经典理论相比较，该衍射理论在大非线性相移的情况下仍然可以得到准确的结果。近场的分析主要采用有限差分时域法(FDTD)，这一方法是求解Maxwell微分方程的直接时域方法，它的实质在于直接将Maxwell方程在空间、时间上离散化，用差分方程代替一阶偏微分方程，从而可以求解出各网格单元的场值，直观地反映电磁场分布情况，是研究超分辨近场结构的有效工具。本部分内容主要介绍了FDTD方法运用中的几个关键问题。 远场光学数值模拟与分析部分首先建立了远场光学数值计算工具——高斯衍射模型，利用MATLAB软件编写了计算程序并进行了相关的验证。接着利用高斯衍射模型研究了超分辨近场结构光盘中bubble微结构的形成过程。理论计算得到的透过率变化曲线与文献报道的实验结果一致，说明我们设计的bubble微结构形成过程的简化模型(包含折射率的变化和形变)可基本反映超分辨近场结构中掩膜结构在激光作用下的结构变化过程，并证明该模型是研究薄膜内微结构的一种有效方法。最后利用高斯衍射模型分析了三种金属氧化物型超分辨近场结构光盘的超分辨读出性能产生差异的原因。研究结果表明读出信噪比与材料的折射率之间存在密切关系，并且通过bubble尺寸的控制可以使CNR得到进一步的提高。 近场光学数值模拟与分析部分我们提出了二元共晶合金掩膜实现近场超分辨的微结构模型，利用时域有限差分法分析了其近场光学特性。大量的实验研究发现以二元共晶合金作掩膜的super-RENS光盘具有较高的读出信噪比，但是其工作机理一直未能得到合理的解释。结合二元共晶合金材料在激光作用下于共晶温度下能够发生共晶转变并可形成多种规则的共晶微纳结构的特点，我们利用FDTD方法对这些周期性共晶微纳结构的近场光强分布特性进行了研究。数值计算结果表明，与空孔和均质结构相比，层状和片状周期结构的近场得到了显著的增强。这种近场增强效应可能是以二元共晶合金作掩膜的超分辨近场结构光盘产生较高信噪比的原因。这也为新型纳米近场光学元件的设计、制备提供了新的思路。 最后的结论部分对本论文的整个工作进行了总结。
英文摘要	This thesis is mainly composed of six sections: introduction, review, methods for simulation and calculation, simulation and analysis for far field, simulation and analysis for near field, conclusion. The section of introduction pointed out that the main purpose of this paper is to further clarify the working mechanism of super-RENS and propose a material selection guidance of mask layer by studying the near-field and far-field optical property of micro-/nano- structures in super-resolution near-field structure (super-RENS) disk using theoretical methods. The section of review described the history and recent progress of near-field optical storage, especially for super-RENS technology. With the development of high definition multimedia system and computer network servers, ultrahigh density, huge capacity and high data transfer rate has become necessary for the next generation optical storage. Super-RENS, which aggregates the advantages of super-resolution technology and near-field optics, has been considered as one of the most promising ultrahigh density optical storage techniques. However, the working mechanism of super-RENS is not very clear yet. The section of methods for simulation and calculation gives a simple introduction of calculation methods for near field and far field. For far field, the z-scan diffraction theory is used. In this theory, a thin nonlinear medium is regarded as a phase-modulated screen and can diffract the Gaussian beam. Based on the Fresnel-Kirchhoff diffraction theory, the complex electric field distribution on the aperture plane can be calculated and then the transmittance can be obtained. For near field, finite-difference time-domain (FDTD) method is used, which is a numerical solution for solving Maxwell’s equations directly. The essence of FDTD is to calculate the electromagnetic fields in each Yee cell by replacing the temporal and spatial derivatives in Maxwell’s equations with their finite-difference equivalences and then get the distribution of electromagnetic fields. This method can be effectively applied to the super-resolution near-field structure. In this section we only clarified several key points of FDTD. In the section of simulation and analysis for far field, the Gaussian diffraction model of super-RENS is firstly set up using MATLAB and is confirmed. Then the process of micro-structural deformation in super-RENS disk is studied by using this model. The calculated results are in good agreement with previously reported experiment results in literatures. This agreement indicated that the simplified model (including change of bubble structure and refractive index) can reflect the real process of structure deformation in super-RENS and confirmed that this Gaussian diffraction model is an effective method for the study of micro-/nano- structure in thin film. Lastly, using this Gaussian diffraction model we analyzed the reason for different CNR of the three MOx-type super-RENS. Results indicated that the readout CNR strongly depended on the refractive index distribution and can be further improved by controlling the size of bubble. In the section of simulation and analysis for near field, we proposed the micro-/nano- structure model of eutectic-binary-alloy mask layer for super-resolution effect and used FDTD to analyze its near-field property. A series of experiments in literatures showed that higher CNR can be achieved when the atomic composition ratio is near the eutectic point of a binary-alloy mask layer in super-RENS. However, the working mechanism is not effectively clarified. In this section, according to the eutectic transition theory of eutectic-binary-alloy, the near-field intensity distribution of the photo-induced periodic eutectic micro-/nano- structure is studied using FDTD. Results indicated that there exists a great enhancement of the near-field optical intensity for the layered and sliced periodic structures compared with those of bare aperture and homogeneous structure. It is the near-field enhancement effect that results in higher readout CNR. And these results may provide a potential new approach to develop functional micro-/nano- photonics structures. The last section summarized the whole work of this thesis.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/15346]
专题	上海光学精密机械研究所_学位论文
推荐引用方式 GB/T 7714	瞿青玲. 近场超分辨光盘中微纳结构的远场和近场光学性质分析[D]. 中国科学院上海光学精密机械研究所. 2004.

个性服务

查看访问统计

相关权益政策

暂无数据

收藏/分享

除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。