非局域非线性耦合器中暗孤子的传输

Propagation of dark soliton in nonlocal nonlinear coupler

研究了空间暗孤子在非局域非线性耦合器中的新解和传输稳定性.发现非局域非线性耦合器中存在稳定的基态暗孤子和多极暗孤子的束缚态.分析了非局域程度、非线性参数、传播常数和耦合系数变化对基态暗孤子的峰值、束宽和功率的影响.讨论了基态暗孤子和多极暗孤子的传输稳定性,发现基态暗孤子在其存在的区域总是稳定的,偶极以及多极暗孤子存在不稳定区间,稳定区间取决于传播常数和介质的非局域程度,并且多极暗孤子的稳定传输还受孤子间距的影响.

The characteristics of fundamental and mutipole dark solitons in the nonlocal nonlinear couplers are studied through numerical simulation in this work.Firstly,the fundamental dark solitons with different parameters are obtained by the Newton iteration.It is found that the amplitude and beam width of the ground state dark soliton increase with the enhancement of the nonlocality degree.As the nonlinear parameters increase or the propagation constant decreases,the amplitude of the fundamental dark soliton increases and the beam width decreases.The power of the fundamental dark soliton increases with the nonlocality degree and nonlinear parameters increasing,and decreases with the propagation constant increasing.The refractive index induced by the light field decreases with the nonlocality degree increasing and the propagation constant decreasing.The amplitudes of the two components of the fundamental dark soliton can be identical by adjusting the coupling coefficient.These numerical results are also verified in the case of multipole dark solitons.Secondly,the transmission stability of fundamental and mutipole dark solitons are studied.The stability of dark soliton is verified by the linear stability analysis and fractional Fourier evolution.It is found that the fundamental dark solitons are stable in their existing regions,while the stable region of the multipolar dark solitons depends on the nonlocality degree and the propagation constant.Finally,these different types of dark dipole solitons and dark tripole solitons are obtained by changing different parameters,and their structures affect the stability of dark soliton.It is found that the multipole dark soliton with potential well is more stable than that with potential barrier.The refractive-index distribution dependent spacing between the adjacent multipole dark solitons favors their stability.