Feasible Conditions for Magnetostatic Wave Envelope Solitons and Their Formation under Optimal Conditions

尽管YIG薄膜由于其窄的铁磁共振共振线宽而被广泛应用于微波谐振器，但对于几乎没有传输损耗的静磁波(MSW)包络孤子在YIG薄膜上的传播还不够窄。采用分步傅立叶方法求解NLS方程。为了在实验中观察到类孤子行为，我们必须使MSW的色散变得很高，使得输入脉冲的波形可以发生足够快的变化，并且在耗散效应占优势之前完成MSW孤子的形成。另一方面，色散越强，形成孤子所需的功率就越大。通过定量研究垃圾孤子的衰减特性，讨论了形成和传播垃圾孤子的可能条件。已经发现MSW波包的幅度衰减率依赖于输入功率水平，其半最大全宽的展宽率(FWHM)也是如此，需要强调的是，输入功率的增加对MSW孤子的衰减的影响相当于损耗的减小。通过将金属平面靠近YIG薄膜或将金属栅放在YIG薄膜表面来控制色散，可以形成静磁表面波(MSSW)亮孤子。在YIG薄膜中使用所谓的孤子效应已经被证明是一种很有前途的产生宽度至少为1 ns的静磁脉冲的技术。

Although yttrium iron garnet (YIG) films are widely used for microwave resonators owing to their narrow ferromagnetic resonance linewidth, it is not enough narrow for the magnetostatic wave (MSW) envelope solitons to propagate on the YIG films almost free of propagation losses.The nonlinear Schr_dinger (NLS) equation with the third order dispersion and dissipative effects has been used to describe MSW envelope solitons. The split-step Fourier method has been used to solve the NLS equation. In order to observe a soliton-like behavior in experiments, we must make the dispersion of the MSW so high that the waveform of an input pulse may make a sufficiently rapid change and the MSW soliton formation may be completed before the dissipative effect becomes prevailing. On the other hand, the stronger the dispersion, the more power is needed to form a soliton.Feasible conditions for MSW soliton formation and propagation have been discussed by quantitatively investigating the decay features of MSW solitons. The amplitude decay rate of MSW wave packets has been found to be dependent on the input power level, so is the broadening rate of their full-width at half maximum (FWHM), and it should be emphasized that the increase of input power has further been proved to have an effect on the damping of MSW solitons which is equivalent to the decrease of loss.The magnetostatic surface wave (MSSW) bright solitons can be formed if the dispersion is controlled by putting a metal plane close to or a metal grating on the surface of a YIG film.The use of so-called soliton effects in a YIG film has been shown to be a promising technique for production of magnetostatic wave (MSW) pulses with at least as short width as 1 ns.