通过数值法对包含拉曼延迟响应的(3+1)维非线性薛定谔方程进行求解,研究了超短脉冲激光在负折射介质中传输时拉曼效应对自聚焦传输特性的影响,着重分析其不同与常规介质的反常传输现象。结果表明:由于负的折射率影响,拉曼效应将导致超短脉冲在自聚焦过程中频谱发生蓝移现象,这与常规介质对应情形相反;而它对负折射介质中超短脉冲的自聚焦特性的影响与常规介质相同,即拉曼效应将诱导自聚焦效应首先发生在脉冲的前沿。本文研究工作对将来利用负折射介质来操控超短光脉冲串产生、自聚焦等许多实际应用领域研究具有重要的指导意义。

Influence of Raman effect on self-focusing propagation properties of ultrashort laser pulse in metamaterials is studied through numerical solutions of (3+1)-dimensional nonlinear Schrdinger equation including the contribution of the Raman delayed response, and the especial attention is paid to the anomalous propagation phenomena not found in ordinary materials. It is found that Raman effect will lead to the occurrence of the blueshifted frequencies during the self-focusing process of ultrashort pulse, opposite to the corresponding case in ordinary materials. However, its influence on the self-focus properties of the self-focusing of ultrashort pulse is the same as the case in ordinary materials, namely, it will make the self-focus occurring firstly in the leading part of pulse. Our works are of very important significance in the practical application, such as controlling a train of ultrashort pulse and self focus etal by using metamaterials.