共查询到20条相似文献,搜索用时 109 毫秒
1.
高阶色散导致的交叉相位调制不稳定性 总被引:2,自引:0,他引:2
在考虑光纤损耗及高阶色散的情况下,以三、四阶色散项的耦合非线性薛定谔方程为基础,研究高阶色散对交叉相位调制不稳定性的影响.研究表明:三阶色散对调制不稳定性不起作用;由于四阶色散的影响,在光纤的正常、反常色散区,交叉相位调制不稳定性均发生在两个频谱区.且反常色散区两频谱区都比正常色散区的宽,反常色散区第二频谱区比正常色散区的更靠近零点.光纤损耗对增益谱的谱宽有较大影响,它使增益的谱宽变窄,且随传输距离的增大谱宽变得更窄. 相似文献
2.
通过计算损耗型单负材料双层异质结构中的透射、反射和吸收随损耗系数的变化,对单负材料双层异质结构基于损耗的光学性质调控进行了研究。首先,对损耗型单负材料单层结构的透射行为进行了计算,给出了单层结构随损耗系数增大的非单调透射的变化图像。接着,计算了损耗型单负材料双层异质结构中的透射、反射和吸收随损耗系数的变化曲线,并分析了不同频率下透射与损耗系数之间的关系。研究结果表明,在远离隧穿频率处,随损耗系数的逐渐增大,异质结的透射呈现出先减小后增大的变化。计算的电磁场强度分布图像表明,双层异质结中透射与损耗系数之间为非单调关系,起源于损耗型单负材料界面处的反常场局域效应,即随着损耗系数的增大,场局域先减弱后增强。 相似文献
3.
在考虑线性损耗的情况下,对硅基纳米波导中皮秒脉冲传输交叉相位调制不稳定性进行了仿真研究。采用微扰和线性稳定性分析方法,理论推导了调制不稳定性产生所满足的色散关系和调制不稳定性增益谱表达式。分析了脉冲光功率、线性损耗和群速度色散系数等参量对交叉相位调制不稳定性的影响,并进行了仿真分析。结果表明,即使在微弱的入射光功率下,仍然存在强烈的交叉相位调制不稳定性现象;交叉相位调制不稳定性不仅可以在反常色散区出现,而且在正常色散区也会发生。波导的线性损耗对交叉相位调制不稳定性增益谱有明显影响。 相似文献
4.
5.
6.
7.
反常电子粘滞性与锯齿崩塌 总被引:2,自引:2,他引:0
本文研究了反常电子热导产生的反常横向电子粘带性的对居齿振荡现象的影响,得出了新的锯齿崩塌时间,解释了大托卡马克上的快崩塌过程。对于不同的反常输运模型,得到了不同的崩塌时间对电子温度的依赖关系,说明了反常粘滞性高温下起着主要的作用。根据崩塌时间估算出的反常热导对的定标关系与耗散漂移波理论的结论基本相同。 相似文献
8.
本文根据拟合得到的gF因子大小,确定了光磁共振实验中的反常共振信号;用数字示波器测量了反常共振射频信号的频谱,计算了反常共振射频信号各高次谐波的大小;通过线性拟合,得到了正常共振信号幅度与射频信号幅度的关系。利用此关系,计算了各高次谐波产生的反常共振信号大小,计算结果与测量值基本一致。频率计连接射频信号源后,射频信号波形和频谱发生明显变化,反常共振信号随着射频信号频谱的变化发生相应改变,进一步证明了反常共振信号由射频信号的高次谐波共振所引起。这些结果表明,用数字示波器探究光磁共振实验中反常共振信号的机理不仅可行,还能定量估算和预测射频信号波形对反常共振信号大小的影响。 相似文献
9.
反常输运与非线性自持磁岛的自洽分析 总被引:3,自引:3,他引:0
从沿磁力线的等离子体电流与粒子径向输运相关的新经典MHD型的广义欧姆定律出发,提出了分析反常输运与非线性自持磁岛的自洽理论模型,基于该模型导出了反常扩散系数及反常电子热导。结果表明,非线性磁岛链可由磁岛调制的反常输动维持,反过来又通过磁岛短路效应维持反常输运。 相似文献
10.
11.
Results concerning the pinning behaviour of thin Nb3Ge films prepared by sputtering and evaporation onto hot sapphire substrates are reported. The validity of scaling laws in the range of magnetic fields up to 13 T has been verified. We have found that the pinning dependence in evaporated films obeys these laws, however, the maximum of the volume pinning force occurs at constant magnetic field value for sputtered Nb3Ge films. A different microstructure of these two types of films is made responsible for the anomalous pinning behaviour described. 相似文献
12.
General expression for the energy loss in Cerenkov radiation due to a charged particle possessing anomalous magnetic moment
is obtained. The expressions include the spin-polarization of the particles. The contribution to the radiation due to anomalous
magnetic moment is found to be small as compared to that due to charge. The interference term of charge and anomalous magnetic
moment gives better contribution as compared to the term containing only anomalous magnetic moment. Polarization of the radiation
as dependent on polarization of beam of particles is studied. The radiation has a dominant nature of linear polarization with
small quantum corrections. The spin-flip also gives quantum correction to strong linear polarization and at threshold when
phase velocity equals velocity of the particle. 相似文献
13.
G. Bergmann 《Solid State Communications》1982,42(8):553-555
The surfaces of thin films of Pb, In and Sn have been superimposed with Fe-impurities down to a coverage of 2%. The magnetic behaviour of the Fe has been measured by means of the anomalous Hall-effect. It was found that the Fe possesses a moment on top of the Pb-, In- and Sn-surface. By increasing the Fe-concentration one passes from an independent impurity regime to ferromagnetism through an intermediate two-dimensional spinglass state. 相似文献
14.
《Superlattices and Microstructures》1998,24(4):291-293
Mesoscopic conductance fluctuations of a two-dimensional electron gas in a one-dimensional periodic array of antidots have been studied experimentally, for the first time. The fluctuations show a quasiperiodic behaviour on magnetic field, with period corresponding to the quantization of magnetic flux through the area of a unit cell of the one-dimensional array. The existence of the quasiperiodic component is explained by an anomalous area distribution of interfering trajectories. 相似文献
15.
We perform finite-pressure Monte Carlo simulations of an effective spin-analogous model with coupled magnetic and lattice degrees of freedom, which has previously been proposed in order to explain the anomalous temperature driven metamagnetic phase transition in α-FeRh. The results are in reasonable agreement with the experimental (p,?T) phase diagram. The critical behaviour of the system along the transition lines is analysed in detail. 相似文献
16.
Claudine Lacroix 《Physica B: Condensed Matter》2009,404(19):3038-3041
While consequences of frustration of magnetic interactions are much studied in localized spin systems, much less studies have been performed on frustrated metallic systems. However, several effects of strong geometrical frustration in metallic correlated system have also been experimentally observed in rare-earth or transition metal compounds: coexistence of magnetic and non-magnetic sites in ordered magnetic structure, heavy fermion behaviour and anomalous Hall effect due to spin chirality are consequences of frustration. An overview of the experimental observations and of the proposed models is given. Other interesting effects due to magnetic frustration in metallic systems, which have been predicted theoretically, are also reviewed. 相似文献
17.
Stan Zurek Faris Al-Naemi Anthony J. MosesPhilip Marketos 《Journal of magnetism and magnetic materials》2008
The behaviour of ferromagnetic materials under very low magnetic field was investigated more than a century ago by Lord Rayleigh. However, it has been shown since that the so-called Rayleigh law fails for very low magnetic fields, although the explanation for this phenomenon was not given. An anomalous B–H behaviour at very low alternating peak flux density in conventional grain-oriented (GO) and non-oriented (NO) electrical steels is reported. It has been found that the initial permeability is constant for all the measured frequencies (from 20 to 400 Hz) at peak flux density below 0.1 mT, and in this region the magnetisation is almost reversible (for both GO and NO). At higher flux density the B–H loops become visibly irreversible, with a relatively narrow (for GO) or very wide (for NO) transition region. For GO the B–H loop becomes visibly “distorted” for all frequencies at around 2 mT. The eddy current loss calculated from the so-called “classical” equation gives values higher than the measured total losses at lower frequencies. Both these measured results are difficult to explain. 相似文献
18.
Coupling of electron spin to optic phonons due to spin—orbit interaction is studied theoretically for small-gap semiconductors in the presence of a magnetic field. We predict an anomalous behaviour of magnetic levels when spin-flip energies become equal to the phonon energy. The effects should be observable in HgTe-type materials. 相似文献
19.
Carreras B.A. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1997,25(6):1281-1321
Transport is the outstanding physics issue in the quest for fusion by magnetic confinement. In spite of the intrinsic difficulty, a great deal of progress has been made in the past 25 years. Experiments have gone from being dominated by high anomalous losses, of the order of Bohm diffusion losses, to operation with no anomalous transport. This success is due to a combination of improved experimental infrastructure and the high degree of knowledge on how to control plasma discharges, Both have made it possible to access enhanced confinement regimes and to unravel new effects in confinement physics. Although there is not yet a complete understanding of the dynamical mechanisms underlying the anomalous transport process, there is some understanding of important components such as the ion transport loss mechanism at the plasma core and of the main mechanism for turbulence suppression in the enhanced confinement regimes 相似文献
20.
K. Raju G. Lalitha K.V. Sivakumar P. Venugopal Reddy 《Solid State Communications》2010,150(19-20):928-931
With a view to understanding the structural, electrical and magnetic, elastic and anelastic behaviour of charge ordered Nd0.6Ca0.4MnO3, systematic investigations were undertaken. The sample was synthesized by a sol–gel route. The sample was characterized by X-ray diffraction (XRD) using a Rietveld refinement technique and was found to have orthorhombic structure with space group Pnma. A study on the variation of electrical resistivity with temperature has been carried out in the range 100–300 K and it was found to exhibit a field induced transition. The ac susceptibility studies show two transition temperatures, which are attributed to charge ordering and a Néel transition. Internal friction and longitudinal modulus studies were carried out using the composite oscillator technique. An effort has been made to explain the observed anomalous behaviour by a qualitative model. 相似文献