论文标题
时间负折射
Temporal negative refraction
论文作者
论文摘要
负折射是一种特殊的波传播现象，当波浪在给定频率下两个本构参数为阴性的常规介质和培养基之间的边界时发生。然后，传输波的相位速度和组速度转动反行。在这里，我们提出了使用时间依赖培养基的负折射现象的时间类似物。我们没有通过空间边界传输波，而是通过人工的时间边界传输它，这是通过将两个参数从常数转换为频率分散的。我们表明，由此产生的动态与空间案例截然不同，在正面和负面方案中同时以反射和折射为特征。我们使用电磁介质在分析和数值上证明了我们的结果。此外，我们表明，通过针对靶向分散，可以使时间边界不反射，同时保留正折射和负折射。
Negative refraction is a peculiar wave propagation phenomenon that occurs when a wave crosses a boundary between a regular medium and a medium with both constitutive parameters negative at the given frequency. The phase and group velocities of the transmitted wave then turn anti-parallel. Here we propose a temporal analogue of the negative refraction phenomenon using time-dependent media. Instead of transmitting the wave through a spatial boundary we transmit it through an artificial temporal boundary, created by switching both parameters from constant to dispersive with frequency. We show that the resulting dynamics is sharply different from the spatial case, featuring both reflection and refraction in positive and negative regimes simultaneously. We demonstrate our results analytically and numerically using electromagnetic medium. In addition, we show that by a targeted dispersion tuning the temporal boundary can be made nonreflecting, while preserving both positive and negative refraction.
