弱非局域非线性介质中的调制不稳定性  

Modulation instability in a weakly nonlocal nonlinear medium with quintic nonlinearity

作　　者：张少武[1] 

机构地区：[1]湖北师范学院物理与电子科学学院,湖北黄石435002

出　　处：《湖北师范学院学报（自然科学版）》2009年第2期10-13,共4页Journal of Hubei Normal University(Natural Science)

摘　　要：采用Fourier变换研究了含5阶非线性的弱非局域介质中平面波的调制不稳定性(MI)。结果表明,正5阶非线性非局域介质中平面波的稳定性质与弱非局域Kerr介质一致,但负的5阶非线性却改变了其稳定性质。自聚焦介质中MI增益谱为有限宽度,谱的最大值和谱宽均随5阶非线性的增大而增大;与此相反,除特定范围外,自去焦介质具有无限宽的MI增益谱,波数的阈值与5阶非线性的符号和大小有关。Modulational instability of the plane waves in weakly nonlocal medium with quintie nonlinearity is studied. It was found that the stability property of plane wave in the medium with sign - positive quintic nonlinearity is in accordance with that in Kerr medium. However, sign - negative quintie nonlinearity qualitatively alters the modulational instability （MI） property. In the self - focusing media, the MI gain spectrum is of finite bandwidth, in which the maximum gain and the gain bandwidth increase with quintic nonlinearity. In contrast, the self - defocusing medium has MI gain spectrum of infinite bandwidth char- acterizing by the threshold value of wave number associated with the sign and size of quintic nonlinearity, except in a special regime.

关 键 词：调制不稳定性 弱非局域性 3—5阶非线性性 

分 类 号：O431[机械工程—光学工程]