Dissertation > Excellent graduate degree dissertation topics show

Simulating the Stimulated Emission Characteristics in ZnO Random Media

Author: YouQiaoQin
Tutor: XieYingMao
School: Gannan Teachers' College
Course: Optics
Keywords: finite difference time domain(FDTD)method ZnO random media stimulated emission localized modes
CLC: O431.2
Type: Master's thesis
Year: 2011
Downloads: 10
Quote: 0
Read: Download Dissertation

Abstract

Based on the growth and photoluminescence experiment of ZnO nanorods, The structrue model of two-dimensional random media in which the center and radius of ZnO nanorods are all disordered is constructed, the structrue model keep unchanged, the lasing mechanism and property of ZnO nanorods is investigated.Firstly, Using ZnO gain phenomenological model, the spectrum characteristics and spatial distribution of optical field in ZnO nanorods random media without gain and loss is simulated numerically by means of the finite difference time domain method. Firstly using Gaussian pulse in ZnO two-dimensional random media, the spatial distribution of optical field presents localization characteristics in the random media. We select observation point in local region. Four typical resonance peaks of observation point occur in ZnO gain range, then using sinusoidal wave corresponding to the resonance peaks instead of Gaussian pulse, the optical field corresponding to the resonance peaks is discussed. We found the optical field of different localized mode has different spatial distribution.Next the spectrum characteristics and spatial distribution of optical field in ZnO nanorods random media with gain and loss is studied. Using the same Gaussian pulse , the same four transmission resonance peaks of observation point occur in ZnO gain range, that is spectrum is only related to the structure of the media, and it does not change with the gain and loss of active random media. Then using monochromatic harmonic excitation instead of Gaussian pulse, the spatial distribution of optical field presents localization characteristics in the random media is found. The shape of the optical field’s relative intensity has nothing to do with the loss and gain, the loss and gain only change the intensity of optical field. Next the effect of pump power on the lasing of the localized mode in active random media is discussed, the result shows that the pump power threshold for different lasing modes is different.The effect of pump area on laser actions in ZnO nanorods random media was studied from several aspects, change the pump intensity, increasing the pump size every two columns from left to right and only pump a zone of localized mode. The pump intensity is fixed, increasing the excitation area (the number of the ZnO nanorods) in localized area and non-local area respectively. We can get some information as following :When the pump intensity is smaller than pump intensity at the lasing threshold, there is no localized mode can be excited no matter how much the pump area, for different pump power, localized modes can be lasing need different critical pump sizes; the pump size is fixed, the relative light intensity increases with a increase of the pump intensity,when the pump intensity exceed the lasing threshold, then the relative light intensity increases rapidly; the pump intensity is constant, pump the local region, with a increase of the pump size, the position of the localized mode moves toward the direction of the increasing of pump area, simultaneously, relative light intensity is also increased; the pump intensity is fixed, distribution and intensity of optical field does not vary with the change of the pump size in unlocal region.

Related Dissertations

CLC: > Mathematical sciences and chemical > Physics > Optics > The light nature of the theory > Quantum optics
© 2012 www.DissertationTopic.Net Mobile