Modeling and Analysis of Super Resolution Near-field Structure

在本篇論文中，我們針對以氧化銀為遮罩層的超解析近場結構光碟（Super resolution near-field structure, Super-RENS）進行分析。氧化銀在經雷射光照射後，會在雷射光點中心溫度較高處解離成大小不一的銀顆粒，我們經由文獻觀察和量測的結果，提出了一個此結構的簡化模型；經由時域有限差分法（FDTD）的模擬，我們證實了此結構對於較小的記錄點會比傳統碟片有較佳的射頻信號。 我們亦根據傳統光碟片的繞射理論，提出一新的架構用於分析此近場結構，並用此理論進行射頻及偏軌信號的模擬；接著探討在有像差（aberration）產生的情形下，其對偏軌信號的影響，最後用有限時域差分法驗證在失焦（defocus） 下，偏軌信號的變化。In this thesis, we analyzed super resolution near-field structure（Super-RENS） with AgOx as mask layer. AgOx will be decomposed to Ag particles with various sizes under higher temperature on the center of laser spot. According to the observation and estimation from the reference, we propose a simple model of Super-RENS. From the finite difference time domain（FDTD） simulation, we proved that it would be better RF signal than DVD’s under smaller recording mark size. According to the diffraction theory used in DVD system, we propose a new theory to analyze the RF signal and tracking error signal of Super-RENS disk. Then we use simulate the tracking error signal under beam aberration. Finally we use FDTD method to simulate the tracking error signal at defocus.Abstract Table of contents List of Figure Chapter 1 Introduction 1.1 Motivation………………………………………………………………………1 1.2 Research Goals…………………………………………………………………2 1.3 Thesis Organization…………………………………………………………….2 Chapter 2 Basic Theory 2.1 The theory of super resolution near-field structure………….………………….4 2.2 Finite Difference Time Domain…………………………………………………5 2.3 Near to far field transformation…………………………………………………8 2.4 Operational signal………………………………………………………………9 Chapter 3 Super-RENS Model and RF Signal Simulation 3.1 Introductionl…………………………………………………………………….14 3.2 FDTD simulation………………………………………………………………..15 3.3 Diffraction theory of laser read-out system……………………………………..22 3.4 Use diffraction theory to analyze Super-RENS disk…………………………….29 Chapter 4 Tracking Error Signal Simulation 4.1 Introduction………………………………………………………………………35 4.2 Beam aberration………………………………………………………………….35 4.3 DPD signal in the presence of defocus…………………………………………..36 4.4 DPD FDTD simulation…………………………………………………………42 Chapter 5 Conclusion…………………………………………………………………..46 Reference………………………………………………………………………………..4