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Numerical Simulations Of Propagation Of Electromagnetic Solitons In Nonlinear Negative-index Materials

Posted on:2008-11-24Degree:MasterType:Thesis
Country:ChinaCandidate:X Y SongFull Text:PDF
GTID:2178360215979855Subject:Communication and Information System
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The negative-index material (NIM) is a novel material and its most impressive property is their negative permittivity and negative permeability. The most difference between NIM and ordinary optical material is the sign of their index. Moreover, the magnetic permeability is dispersive in the NIM, which is a constant in ordinary positive-index material. Nowadays, it is considered that the NIM to be a revolutionary influence optical technology when NIM in the near IR and optical range have also been experimentally demonstrated. It has become one of the front and focus area in physics and optics research. Additionally, the research of propagation of electromagnetic soliton in nonlinear NIM not only improves the ordinary nonlinear optical region, but also brings the new technologies of optical controlling. By incorporating the novel properties of NIM, one can deal with the problem of nonlinear pulse propagation in metamaterial by using the same way as in ordinary material, or even directly borrowing the existing models for pulse propagation in ordinary materials. By doing so, a general physical model suitable for few-cycle pulse propagation in metamaterial is obtained. The new phenomena and new characteristics in electromagnetic soliton propagation are clearly described, and also the physical mechanisms are analyzed. The main research results are listed below:Firstly, in addition to the opposite of the sign of refractive index, the important difference between NIM and ordinary optical material is the magnetic permeability are dispersive in the NIM, which is a constant in ordinary positive-index material. This requires us to combine the properties of NIM with the characteristic of propagation of electromagnetic soliton to rebuild the model of electromagnetic soliton propagation in NIM. Also, it could provide the theoretical basis for the research of electromagnetic soliton propagation. From the Maxwell equations, using the generalized nonlinear Schr?dinger equation derivation methods, and combining the properties of NIM, a more universal model that describes ultrashort electromagnetic pulse propagates in NIM is found. The model clearly shows the unique properties of NIM, and also shows the differences of the propagation models between NIM and ordinary material, which are due to the dispersive magnetic permeability.Secondly, the propagation of electromagnetic soliton in NIM is limited by various physical factors. And numerical simulation has become a crucial research method for the complicated theoretical analysis. Based on the physical model of electromagnetic soliton propagation in the NIM, the computer program, which can simulate the process of linear and nonlinear propagation of optical pulses, has been independently developed. Compared with the experimental and theoretical results reported in literatures, the validity of the computation results of our program is confirmed.Finally, the roles of the negative self-steepening and the second-order nonlinear dispersion effects in soliton propagation, which are resulted from the dispersive permeability of NIM, are analyzed. It is shown that, like the positive SS effect, the negative SS effect also leads to the asymmetry of soliton, the shift of the soliton center, and the decay of higher-order solitons, but the direction of the shift is decided by the sign of SS. The sign of second-order nonlinear dispersion effect decides the broadening of pulse, and it also leads to the intensity of pulse's periodic change.
Keywords/Search Tags:nonlinear propagation, negative-index material, the split-step Fourier method, electromagnetic soliton, dispersive permeability, self-steepening, second-order nonlinear dispersion
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