Dissertation > Excellent graduate degree dissertation topics show

Subwavelength Imaging Using Periodic Metal-Dielectric Layered Structure

Author: LiWenLing
Tutor: LiChunFei
School: Harbin Institute of Technology
Course: Optics
Keywords: Metal - dielectric cycle membrane structure Subwavelength imaging Effective medium theory
CLC: O433.4
Type: Master's thesis
Year: 2008
Downloads: 27
Quote: 0
Read: Download Dissertation

Abstract

Subwavelength imaging devices directly to the spread of the far-field and near-field component of the object light field to a certain distance and reproduce things like function. A device having such a function as a breakthrough of the diffraction limit of the conventional optical element, the imaging resolution can be less than a half wavelength of incident light, to achieve the magnitude of subwavelength. Subwavelength imaging in the visible range recent metal - dielectric cycle membrane structure has become a hot research topic, and is expected to improve the resolution of optical printing. The influence of metal - dielectric cycle membrane structure subwavelength imaging intensity and resolution of the key factors is the value and the phase of the communication field spatial frequency range, the transmittance mode. Based on the study of materials, structure parameters and metal - electrical the media cycle membrane structure propagation field spatial frequency range of relations, and to explore the impact of the transmission spectrum of a metal material loss. As a basis for the structure of the visible band subwavelength imaging parameter optimization, real material parameters of the imaging resolution numerical verification. Ignore the material loss, by solving the Bloch eigen equation to determine the relationship between the metal - dielectric cycle film materials, structural parameters and propagation field spatial frequency range. Effective medium theory, the scope of the increase of the frequency range of the propagation field increases. And the dielectric constant of the dielectric and metal ratio of the closer to -1, the smaller the period thickness, the larger the spatial frequency range of the propagation field. Effective medium theory applies within the metal - dielectric cycle membrane structure can be equivalent to the space homogeneous uniaxial crystal. On this basis, this paper discussed when the duty cycle of the metal layer for different values ??of the metal material loss of the transmission spectrum. That under the premise of the distance field can be transmitted in the structure, metal duty most hours transmittance higher modulus value, and the phase is flat, is conducive subwavelength imaging. To reduce the loss, lead to the reduction of the transmittance, the metal recommended to choose the silver, and the dielectric permittivity as high as possible, and the working wavelength should be as long as possible. Based on the discussion of the transmission spectrum, optimize the design of the metal - dielectric cycle film subwavelength imaging in the visible range of the best materials, the structure and parameters. Recommended Ag / GaP cycle membrane structure, the metal for 47.5% duty cycle, and the cycle of a thickness of less than 30 nm. Spectral analysis by Fourier angle the numerical method validation, when the structure of the total length of 1μm, are available in the operating wavelength of 545nm wavelength resolution of 1/10, the vertical incident amplitude transmittance of 13%.

Related Dissertations

CLC: > Mathematical sciences and chemical > Physics > Optics > Spectroscopy > Spectroscopy
© 2012 www.DissertationTopic.Net Mobile