共查询到19条相似文献,搜索用时 953 毫秒
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基于分数阶非线性薛定谔方程,研究分数阶衍射效应下蜂窝晶格中带隙涡旋光孤子的存在性与传输特性.首先采用平面波展开法得到蜂窝晶格能带结构,其次在带隙结构中分别采用改进的平方算子迭代法、分步傅里叶法和傅里叶配置法研究含有蜂窝晶格势的分数阶非线性薛定谔方程中带隙涡旋孤子的模式及其传输特性.研究结果发现带隙涡旋孤子的传输特性受Iévy指数和传播常数的影响.在稳定区间,带隙涡旋孤子可以稳定传输,而在非稳定区间,带隙涡旋孤子会随着传输距离的增加而逐渐汇聚,失去环状结构演变为基孤子.且Lévy指数越大,带隙涡旋孤子能够稳定传输的距离越长,功率越低.此外,相邻晶格同相位两个带隙涡旋孤子与旁瓣能量相叠加,反相位两带隙涡旋孤子与旁瓣能量相抵消,传输过程中逐渐失去环状结构,演化为类偶极子模式,且受方位角调制影响而周期性旋转.在非相邻晶格处两带隙涡旋孤子,由于旁瓣影响较小,带隙涡旋孤子在传输过程中能较好地保持环状结构. 相似文献
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研究了金属和自散焦周期性介质界面表面间隙孤子的形成及其稳定性.这种表面间隙孤子只存在于超过格子深度临界值的有限间隙内,在第一间隙和第二间隙内间隙孤子存在区域包括稳定区域和不稳定区域,第二间隙内格子深度的临界值远大于第一间隙内格子深度的临界值.在第一间隙内,对给定的格子深度,当传播常数增大时,表面间隙孤子的能流变小,格子区域内表面间隙孤子振荡拖尾变短.对给定的传播常数,表面间隙孤子的能流随格子深度的增加而增大,增大格子深度能把表面间隙孤子由不稳定态转为稳定态.不稳定表面间隙孤子在传输中向横轴正向偏转,偏转角度随格子深度的增加而变小,其主瓣传播轨迹是一条锯齿形曲线.在第二间隙内,表面间隙孤子有较多的拖尾振荡,不稳定区域靠近存在区域的上限,并且随着传播常数增加而逐渐减小. 相似文献
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研究了一维光晶格中超流费米气体的能隙孤子. 应用平均场理论和超流费米气体的流体动力学模型, 利用变分法得到了在整个跨越区超流费米气体在光晶格中存在带隙孤子的条件, 即原子间的非线性相互作用项与系统化学势以及晶格深度的相互关系. 通过对超流费米气体的基态能隙孤子空间分布的分析与对比, 揭示了在一维情况下超流费米气体能隙孤子的存在并发现超流费米气体能隙孤子在整个跨越区当系统从Bose-Einstein凝聚端跨越到BCS端时孤子存在的条件与孤子空间分布存在明显的差别. 相似文献
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光孤子传输的实验研究 总被引:1,自引:0,他引:1
本文采用正常色散光纤对增益开关型(GS-DFB)的光孤子源所带的红移啁啾进行补偿,获得接近变换极限的类孤子脉冲,并成功地观测到随功率增加输出脉宽下降的非线性孤子效应。 相似文献
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研究了非宇称时间对称复数势下非线性耦合器中多类型非局域孤子的存在性和稳定性,发现基态孤子、偶极孤子、多极孤子分别从线性谱中不同的离散特征值分叉出来形成孤子族,其功率受非局域程度和传播常数的影响.在相变以下,各个类型孤子均在相对较低功率区间是稳定的.随着非局域程度的增加,基态孤子族的稳定区域变小,其他孤子族的稳定区域则变大.在相变以上,基态孤子则在相对中功率区是稳定的,并且从第二大离散特征值分叉出的偶极孤子不存在稳定区域.孤子线性稳定性分析结果中的特征值总是以共轭对的形式出现.此外,还研究了耦合系数对孤子态的影响. 相似文献
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The contrast between defect solitons in parityben time symmetric superlattice and simple-lattice complex potentials 下载免费PDF全文
The existence and stability of defect superlattice solitons in parity-time (PT) symmetric superlattice and simple-lattice complex potentials are reported. Compared with defect simple-lattice solitons in similar potentials, the defect soliton in superlattice has a wider stable range than that in simple-lattice. The solitons' power increases with increasing propagation constant. For the positive defect, the solitons are stable in the whole region where solitons exist in the semi-infinite gap. For the zero defect, the solitons are unstable at the edge of the band. For the negative defect, the solitons propagate with the shape of Y at low propagation constant and propagate stably at the large one. 相似文献
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The existence and stability of solitons in one-dimensional multilayer photonic crystals potentials are reported. For all of the solitons, there exist cutoff points of the propagation constant below which the solitons vanish in the semi-infinite gap. The fundamental solitons are stable in the whole range where solitons exist. The antisymmetric dipole solitons can be stable when the propagation constant closes to the cutoff point. The range of stability for symmetric tripole solitons is changed with modulation depth and width of the multilayer photonic crystals potentials. The power of solitons increases with increasing of propagation constant and modulation width or decreasing of modulation depth of the potentials. 相似文献
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We reveal theoretically the existence and stability of surface defect solitons (SDSs) at interfaces between dual-frequency and simple lattices with focusing saturable nonlinearity. Solitons with some unique properties exist in such composite structures with the change of defect intensity. For zero defect or positive defect, the surface solitons exist at the semi-infinite gap and cannot exist in the first gap, and solitons are stable at lower power but unstable at high power. For the case of negative defect, the surface solitons exist not only in the semi-infinite gap, but also in the first gap. With increasing the defect depth, the stable region of surface solitons becomes narrower in the semi-infinite gap, these solitons are stable within a moderate power region in the first gap within unstable solitons in the entire semi-infinite gap. 相似文献
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Y. Tan F. Chen P. P. Beli?ev M. Stepi? A. Maluckov C. E. Rüter D. Kip 《Applied physics. B, Lasers and optics》2009,95(3):531-535
Photovoltaic photorefractive binary waveguide arrays are fabricated by proton implantation and selective light illumination
on top of an iron-doped near stoichiometric lithium niobate crystal. Linear discrete diffraction and nonlinear formation of
gap solitons were investigated by single-channel excitation using Gaussian light beams coupled into either wide or narrow
waveguide channels. The results show that, at low power, linear light propagation leads to discrete diffraction, whilst for
higher input power the focusing mechanism dominates, finally leading to the formation of gap solitons in the binary waveguide
arrays. Our simulation of light propagation based on a nonlinear beam propagation method confirms the experimental findings. 相似文献
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We experimentally study dispersive shock waves in nonlinear waveguide arrays. In contrast with gap solitons, the nonlinearity here pushes the propagation constant further into the transmission bands, facilitating Bloch mode coupling and energy transport. We directly observe this coupling, both within and between bands, by recording intensity in position space and power spectra in momentum space. 相似文献
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The existence and stability of defect solitons supported by parity-time (PT) symmetric defects in superlattices are investigated. In the semi-infinite gap, in-phase solitons are found to exist stably for positive defects, zero defects, and negative defects. In the first gap, out-of-phase solitons are stable for positive defects or zero defects, whereas in-phase solitons are stable for negative defects. For both the in-phase and out-of-phase solitons with the positive defect and in-phase solitons with negative defect in the first gap, there exists a cutoff point of the propagation constant below which the defect solitons vanish. The value of the cutoff point depends on the depth of defect and the imaginary parts of the PT symmetric defect potentials. The influence of the imaginary part of the PT symmetric defect potentials on soliton stability is revealed. 相似文献
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We experimentally investigate the interaction of counterpropagating discrete solitons in a one-dimensional waveguide array in photorefractive lithium niobate. While for low input powers only weak interaction and formation of counterpropagating vector solitons are observed, for higher input powers a growing instability results in discrete lateral shifting of the formed discrete solitons. Numerical modeling shows the existence of three different regimes: stable propagation of vector solitons at low power, instability for intermediate power levels leading to discrete shifting of the two discrete solitons, and an irregular temporal dynamic behavior of the two beams for high input power. 相似文献
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基于强非局域非线性介质中的Snyder-Mitchell模型,利用分离变量法得到了(1 1)维光束传输的厄米-高斯型解析解.比较厄米-高斯型解析解与非局域非线性薛定谔方程的数值解,证实了,在强非局域条件下,该厄米-高斯型解与数值解完全吻合.对厄米-高斯光束的传输特性进行研究,结果表明,光束束宽会出现周期性的压缩或者展宽现象.并且得到了实现厄米-高斯光束稳定传输的临界功率、厄米-高斯孤子解及传输常量,临界功率与厄米-高斯光束的阶数无关,但传输常量随阶数的增加而增加.高斯呼吸子和高斯孤子就是基模厄米-高斯呼吸子和基模厄米-高斯孤子. 相似文献
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The existence and stability of defect solitons in defective PT potentials with real part of dual-frequency lattices are reported. For positive defects, fundamental solitons are always stable in the semi-infinite gap and nonexistent in the first gap. While for negative defects, in the semi-infinite gap, fundamental solitons are stable in most of their existence region apart from low power region, but all the fundamental solitons are stable in the first gap. Dipole solitions are unstable in the whole semi-infinite gap regardless of defects, but in the first gap they can be stable in the low power region for positive defects. 相似文献