Centre for Optical and Electromagnetic Research, Zhejiang Provincial Key Laboratory for Sensing Technologies, State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, China.
Sci Rep. 2012;2:583. doi: 10.1038/srep00583. Epub 2012 Aug 16.
It was claimed that the incident light can be gradually slowed down and finally trapped in a tapered metamaterial waveguide. Here we show that the energy incident from the input port of the tapered metamaterial waveguide will be totally reflected (instead of being trapped) due to the strong intermodal coupling between the forward and backward modes. The underlying physical mechanism for this strong intermodal-coupling is given. The occurrence of energy reflection is unambiguously proved using several independent methods, (1) the semi-analytical mode matching technique, (2) the numerical finite element simulation, (3) the requirement of energy and momentum conservation, and (4) an experimental verification at microwave frequency. The dream of 'trapped rainbow' for storage of light might still be possible if this intermodal coupling could be blocked, and our study provides a useful guidance for such an endeavor.
据称，入射光可以逐渐减速，并最终被困在锥形超材料波导中。在这里，我们表明，由于前向和后向模式之间的强模式耦合，从锥形超材料波导输入端口入射的能量将完全被反射（而不是被捕获）。给出了这种强模式耦合的物理机制。使用几种独立的方法（1）半解析模式匹配技术，（2）数值有限元模拟，（3）能量和动量守恒的要求，以及（4）微波频率的实验验证，明确证明了能量反射的发生。如果能够阻止这种模式耦合，那么存储光的“捕获彩虹”的梦想仍然有可能实现，我们的研究为此提供了有益的指导。
