负折射介质中超短脉冲的反常分裂现象

摘要

对超短脉冲在负折射介质中的传输特性进行了研究,着重分析其不同于常规介质的反常脉冲分裂现象.结果表明:由于负的折射率影响,介质将通过反常群速度色散与自散焦非线性的相互作用机理来诱导脉冲的对称分裂.同时,分析由色散磁导率所导致的可控自陡效应对脉冲分裂的影响,发现负折射介质中正负的自陡效应都会引脉冲非对称分裂.其中负的自陡效导致脉冲裂变后其后沿比前沿高,这与常规介质自陡效应(恒为正)情形相同；而负折射介质正的自陡效应对脉冲分裂影响刚好与前者相反,即裂变后脉冲后沿比前沿低.%The properties of ultrashort pulse propagation in metamaterials (MMs) are investigated, and special attention is paid to the anomalous phenomena of pulse splitting inaccessible in ordinary materials. It is found that the interaction of anomalous group velocity dispersion(GVD) and self-defocus effect will lead to the symmetric pulse splitting due to negative index in MMs. In addition, we have investigated the influence of controllable self-steepening(SS) induced by dispersive magnetic permeability on the pulse splitting. It is shown that both positive and negative SS lead to the asymmetric pulse splitting in MMs. Analysis shows that negative SS effect gives rise to the trailing pulse being higher than the leading pulse, same as the corresponding case in ordinary material; positive SS in MMs causes the opposite of the previous case, namely, the trailing pulse being lower than the leading pulse.