Xiaohua Cui*, Xiaoqing Huang, Zengru Di.Target wave imagery in nonlinear oscillatory systems. Europhysics letters, 112(2015)54003

摘要：几个世纪以来，我们已经熟知波的各种传播行为，线性和非线性系统内波都可以反射、衍射、正常和反常折射等等。但是在线性系统内常见的成像现象目前在非线性系统还没有相关的研究报导。在本文，我们发现了非线性靶波的成像现象。通过在一个区域周期性驱动产生一个固定的靶波波源，我们在界面的另一侧观察到了明显的靶波像。这跟线性系统的成像完全不同，我们在没有借助仪器的情况下，仅利用非线性系统的非均匀性观察到了成像现象。在文章中我们详细讨论了成像的过程和各个特征。该现象的发现对于非线性波形为的理解，和设计新型的功能材料具有重要意义。

Abstract:

Scientists have been familiar with various phenomena of wave propagation for several centuries, such as reflection, diffraction, normal and negative refraction in both linear and nonlinear systems. However, there has been no report about wave imagery in nonlinear systems which is a well-known phenomenon in linear optics. By periodically pacing a small area of a medium in one side of the interface, we reveal target wave imagery in the medium of the other side of the interface. We demonstrate that unlike what happens in linear optics, with certain proper parameter sets, imaging target waves in nonlinear systems can form without apparatus. The imagery process has been discussed in detail. Moreover, the position of the image will move when the core of the pacing-generated target wave changes. This imagery phenomenon provides a new insight into the understanding of the behavior of nonlinear waves, and is helpful to design new functional materials.

Fig1. Target wave imagery is observed in the right medium. The imaging target waves are NWs which are observed by continuous snapshots of spatial patterns. In other words, the pacing-generated target waves which are AWs propagate, crossing the interface, and then form the imaging target waves in the right medium.