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Impacts of higher-order dispersions and saturable nonlinearities on modulation instability in negative-refractive metamaterials 下载免费PDF全文
On the basis of the standard linear stability analysis and Drude electromagnetic model,the impacts of higher-order dispersions and three kinds of typical saturable nonlinearities on modulation instability(MI) have been analyzed and calculated for negative-refractive metamaterials(MMs).Our results show that the MI gain spectra consist of only one spectral region instead of one or two regions in ordinary materials,which may be close to or far from the zero point.Particularly,the spectrum far from the zero point has a high cut-off frequency but a narrow spectral width,which is obviously beneficial to the generation of high-repetition-rate pulse trains.Moreover,MI characteristics here will vary with the normalized angular frequency which can be modified by adjusting the structures of negative-refractive MMs,signifying the controllability of bistable solitons and MI based applications.The effects of saturable nonlinearities are similar to those in ordinary materials. 相似文献
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为探究光纤负五阶非线性和光脉冲预啁啾对高斯光脉冲频率啁啾和频谱的综合影响,在忽略光纤色散的情况下,利用包含三五阶非线性的扩展非线性薛定谔方程,计算和分析了啁啾高斯脉冲的频谱和总啁啾。结果表明,脉冲无预啁啾时,负五阶非线性的存在可使脉冲频率啁啾的形状由单“S”形变为双“S”形,并使脉冲的中心附近由正啁啾变为负啁啾。此外,负五阶非线性的存在使预啁啾对脉冲频谱的影响发生了较大的变化。预啁啾与非线性所致啁啾叠加后对脉冲频谱的谱峰数目影响较小,而对能量在各个谱峰上的分布影响较大,在某些最大非线性相移下,甚至会出现总啁啾减小使谱峰值数目增加的情况。该研究对光开关、光脉冲压缩以及光纤通信系统等领域的深入发展具有一定的指导意义。 相似文献
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Generation of time-dependent ultra-short optical pulse trains in the presence of self-steepening effect 下载免费PDF全文
Starting from the extended nonlinear Schr?dinger equation in
which the self-steepening effect is included, the evolution and the
splitting processes of continuous optical wave whose amplitude is
perturbed into time related ultra-short optical pulse trains in an
optical fibre are numerically simulated by adopting the split-step
Fourier algorithm. The results show that the self-steepening effect
can cause the characteristic of the pulse trains to vary with time,
which is different from the self-steepening-free case where the
generated pulse trains consist of single pulses which are identical
in width, intensity, and interval, namely when pulses move a certain
distance, they turn into the pulse trains within a certain time
range. Moreover, each single pulse may split into several
sub-pulses. And as time goes on, the number of the sub-pulses will
decrease gradually and the pulse width and the pulse intensity will
change too. With the increase of the self-steepening parameter, the
distance needed to generate time-dependent pulse trains will
shorten. In addition, for a large self-steepening parameter and at
the distance where more sub-pulses appear, the corresponding
frequency spectra of pulse trains are also wider. 相似文献
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Generation of High-Repetition-Rate Pulse Trains through the Continuous-Wave Perturbed by a Weak Gaussian Pulse in an Optical Fiber 下载免费PDF全文
A new means of generating all-optically high-repetition-rate pulse trains is proposed and numerically demonstrated in an optical fiber. Our numerical simulations show that, due to the modulation instability effect, the initial continuous-wave with a weak optical pulse instead of conventional weak sinusoidal modulation imposed on it can gradually evolve into high-repetition-rate pulse trains. However, the generated pulse trains take on different features from the conventional case in terms of their widths, intensities, intervals, numbers, and pedestals. 相似文献
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直接从异向介质中包含饱和非线性、自陡峭和二阶非线性色散效应的非线性扩展传输方程出发,采用线性稳定性分析法,导出了调制不稳定性的色散关系、不稳定条件、无量纲的临界扰动频率和增益谱。计算和讨论了异向介质正折射区无量纲的增益谱随归一化角频率和入射功率密度的变化关系。结果表明,在异向介质正折射区,随归一化角频率和入射功率密度的不同,增益谱将会出现扰动频率大于零、扰动频率大于某个非零临界值、扰动频率大于零而小于某个非零临界值3种形式。在归一化角频率较小时,调制不稳定性可能出现阈值入射功率密度;且在较小的入射功率密度时,调制不稳定性只能出现在大于某个临界频率时。 相似文献
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二极管阵列检测-激光诱导荧光光度法测定食品中痕量铜 总被引:5,自引:0,他引:5
为了建立食品中痕量铜的新分析方法,本文利用自行组装的激光诱导荧光-CCD二极管阵列检测器-计算机联用装置,研究了铜催化H2O2氧化罗丹明B的反应体系,在氨-氟化铵(pH=9.0)缓冲溶液中,激发波长532.0nm,发射波长580.0nm条件下,采用催化荧光光度法实现了食品样品中痕量铜的测定,方法的线性范围0.5-4.0ug/L,方法的检出限为0.5ug/L,加标回收率为86.9%-108.6%,s相对偏差不大于9.70%。 相似文献