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The Character Of Femosecond Propagation In Subwavelength Metallic Grating

Posted on:2010-02-11Degree:MasterType:Thesis
Country:ChinaCandidate:M N ZhangFull Text:PDF
GTID:2178360275463047Subject:Optics
Abstract/Summary:PDF Full Text Request
Near-field optics is a new interdisciplinary subject which studies the optical phenomena within one wavelength, and it breaks free from the limitation of conventional optical resolution. It is also the category of optics for the femtosecond through the structure of nanometer metallic grating.There is important base signification for the research of the enhanced transmission through the nanometer metallic structures by researching the transmission characteristic of the ultrashort pulsed laser going the nanometer metallic grating,and there is theoretics value for the study of pulse plastic and increasing the pulse's width .Femtosecond pulse by the nano metal grating of the transmission characteristics of the study on surface plasmon enhanced transmission in the metal structure has an important role in the academic value.This paper applys to two-dimensional metal dispersion finite difference time domain (FDTD)method , and the introduction of a model Drode package prepared for ultrashort pulse under different conditions by the nano-metal structure of the distribution of time-domain signal the numerical simulation. By changing the metal silver (Ag) film thickness, the width of the structure of nano-metal, grating period, incident pulse effective relaxation time, receiving the location, access to the femtosecond pulse nano-metal structure by the time-domain signal distribution, and Fourier transform spectra of the corresponding distribution, analyzed the distribution of time-domain signal of the reasons. In this paper, the ideal conductor at the same time through the membrane and metal structure of Ag control of surface plasmon plasmon enhanced transmission at the role of analysis. The whole paper is divided into five chapters. By solating the equation of Maxwell the text gives the formula of FDTD.The first chapter introduces the research background of the subject, a brief overview of the surface plasmon plasmon at the near-field optical applications, as well as the basic theory of femtosecond and the development of the status .In chapter 2, we gives the finite difference time domain method (FDTD) and the characteristics of the basic principles discussed in FDTD method, as well as the stability of the numerical solution of time step and space step length relationship, give a finite difference time domain method currently used perfectly matched layer (PML) absorbing boundary conditions.Chapter 3, for a negative refractive index properties of the metal, imports a Drode (Drode) dispersion model, and prepare of the Dispersive FDTD program independently.Chapter 4 uses of dispersion of the FDTD computational procedures to simulate the femosecond pulse through the nano-metal structure of the distribution of time-domain signal, and gains the corresponding spectrum distribution by Fourier transform.By changing the metal silver (Ag) film thickness, the width of nano-metal structure, grating period, and the incident pulse effective relaxation time, we researches the transmission characteristics of the femosecond pulse going the nano metallic structure. According to the distribution of time-domain signal and the corresponding spectral distribution of femtosecond pulse by the nano metal grating transmission characteristics are analyzed. By comparing the time-domain signal distribution of outputing of the femtosecond pulse through the conductor and the Ag-plated metal structure of the membrane ,a simple analysis is given about the effect of the surface plasmon in the enhanced transmission of nano-metal structures.In chapter 5, on basis of the Finite-difference time-domain technique, the temporal transmission characteristics of the femtosecond pulse through a high-density grating for the perfect conductor are developed. The calculation results show that the temporal waveform of the transmitted pulse through the grating varies with the incident pulse width and is influenced obviously by the grating parameters. Many interesting phenomena, such as the spread of the transmitted pulse, the fluctuation of the pulse envelope, the distortion of the pulse oscillation and the superluminal phenomenon, appear under proper conditions.In chapter 6, we give a summary of this paper, and put forward the following work.
Keywords/Search Tags:finite-difference time-domain (FDTD), nanostructure, femosecond, surface plasmon polaritons
PDF Full Text Request
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