Engineering the electric and magnetic dispersive responses of artificial media

工程人工介质的电和磁反应我们的许多现代便利和技术进步都是由于我们有能力控制和修改自然产生的材料的行为，并制造出具有自然界所不具备的特性的人工材料。在电磁理论中，材料的行为和响应通常根据所谓的“色散效应”进行分类。根据研究人员感兴趣的领域和专业知识，他或她可能会使用不同的描述，如各种延迟（例如，相位延迟、群延迟、群延迟色散等）、指数或速度来表征相同的色散效应。尽管有这些不同的术语，但我们可以注意到，各种延迟、指数和速度之间存在着基本而重要的关系。这个提案的标题传达了我们的愿望，即通过合成人工材料并利用其新特性来管理、操纵和补偿上述各种延迟、指数或速度——色散效应。这种制造具有自然系统中没有的特性的人造材料的能力使我们能够展示一些非常不寻常和反直觉的现象；例如，证明负折射率和观察负或超光速群延迟和群速度。在第一种情况下，一束光的折射似乎与通常预期的相反，在第二种情况下，电磁脉冲的峰值（或包络线）在输入脉冲的峰值（或包络线）到达输入端之前出现在输出端。尽管它们的外表与直觉相悖，但这两种效果都是因果关系，完全符合我们的基本物理定律。在本提案中，我们打算在分散工程范式的背景下进一步研究这些效应的理论和实践意义。

ENGINEERING THE ELECTRIC AND MAGNETIC RESPONSES OF ARTIFICIAL MEDIA Much of our modern conveniences and technological advances are the consequence of our ability to control and modify the behaviour of naturally occurring materials and to manufacture artificial materials with properties otherwise absent in the natural world.  In electromagnetic theory, the material behaviours and responses are often classified according to the so called "dispersive effects."  Depending on the researcher's area of interest and expertise, he or she may use different descriptions such as various delays (for example, phase delay, group delay, group delay dispersion, and so on), indices, or velocities to characterize the same dispersive effects.   Despite these different terminologies, we may note that fundamental and important relations exist among the various delays, indices, and velocities.  The title of this proposal then conveys our desire to manage, manipulate, and compensate the aforementioned various delays, indices, or velocities - the dispersive effects - by synthesizing artificial materials and utilizing their novel properties.   This ability to manufacture artificial materials with properties not found in the natural systems has allowed us to demonstrate some very unusual and counter intuitive phenomena; for example, the demonstration of negative index of refraction and the observation of negative or superluminal group delays and group velocities.   In the first case a beam of light seems to be refracted opposite to what is commonly expected, and in the second case, the peak (or envelope) of an electromagnetic pulse appears at the output terminal before the peak (or envelope) of the input pulse has reached the input terminal.  Despite their counter intuitive appearances, both effects are causal and in complete agreement with our fundamental physical laws.   In the present proposal, we intend to further investigate the theoretical and practical implications of these effects in the context of Dispersion Engineering paradigm.