Abstract Electromagnetic (EM) metamaterials are artificially engineered media composed of subwavelength unit cells, which achieve exotic EM properties beyond the limits of natural materials and provide great freedom to manipulate EM waves. Here, we review the recent progress on metamaterials in terms of three aspects: effective medium metamaterials, plasmonic metamaterials, and information metamaterials, respectively. In the first section for the effective medium metamaterials, we summarize the fundamental physics and typical applications such as invisibility cloaks, lenses, antennas, and other passive devices. Tunable, reconfigurable, and active metamaterials are also introduced. In the second section, we review the research progress of single plasmons at optical frequencies, and then present highly efficient excitation methods of spoof surface plasmon polaritons (SPPs) and introduce typical passive and active SPP devices such as waveguides, beam splitters, filters, directional couplers, amplifiers, and second harmonic generators. SPP on-chip components and circuits are also investigated with the remarkable advantages in crosstalk reduction to solve the signal-integrity problem, which has challenged to the microwave devices and integrated circuit technologies for many years. Subsequently, spoof localized surface plasmons (LSPs) having novel resonant modes and potential application in high sensitivity sensors are illustrated. In the third section, we first give a brief introduction of EM metasurfaces as well as their applications in generation of optical vortex beams, holograms, and metalenses, and then give a comprehensive review on the recently proposed information metamaterials, including digital coding metamaterials and field-programmable metamaterials, by taking account of the physical principles and their new functions in real-time manipulation of the EM waves such as anomalous reflections or refractions, radar cross section (RCS) reductions, and beam scanning. We further demonstrate the applications of programmable metamaterials in programmable radar, imaging, wireless communication, and hologram systems. Finally, an outlook of the future directions of metamaterials is offered.

中文翻译：

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超材料最新进展：从有效介质模型到实时信息处理系统

摘要 电磁 (EM) 超材料是由亚波长晶胞组成的人工工程介质，可实现超越天然材料极限的奇异电磁特性，并为操纵电磁波提供了极大的自由度。在这里，我们分别从三个方面回顾了超材料的最新进展：有效介质超材料、等离子体超材料和信息超材料。在有效介质超材料的第一部分中，我们总结了基本物理和典型应用，例如隐形斗篷、透镜、天线和其他无源器件。还介绍了可调谐、可重构和活性超材料。在第二部分中，我们回顾了光频单等离子体的研究进展，然后介绍了欺骗表面等离子体激元 (SPP) 的高效激发方法，并介绍了典型的无源和有源 SPP 器件，例如波导、分束器、滤波器、定向耦合器、放大器和二次谐波发生器。还研究了SPP片上元件和电路在降低串扰方面的显着优势，以解决多年来对微波器件和集成电路技术提出挑战的信号完整性问题。随后，说明了具有新型谐振模式和在高灵敏度传感器中的潜在应用的欺骗局部表面等离子体 (LSP)。在第三部分，我们首先简要介绍了 EM 超表面及其在产生光学涡旋光束、全息图和超透镜中的应用，然后通过考虑物理原理及其在实时操纵电磁波（例如异常反射或折射）中的新功能，对最近提出的信息超材料（包括数字编码超材料和现场可编程超材料）进行全面回顾，雷达截面 (RCS) 减少和波束扫描。我们进一步展示了可编程超材料在可编程雷达、成像、无线通信和全息系统中的应用。最后，展望了超材料的未来发展方向。通过考虑物理原理及其在实时处理 EM 波中的新功能，例如异常反射或折射、雷达横截面 (RCS) 减少和波束扫描。我们进一步展示了可编程超材料在可编程雷达、成像、无线通信和全息系统中的应用。最后，展望了超材料的未来发展方向。通过考虑物理原理及其在实时处理 EM 波中的新功能，例如异常反射或折射、雷达横截面 (RCS) 减少和波束扫描。我们进一步展示了可编程超材料在可编程雷达、成像、无线通信和全息系统中的应用。最后，展望了超材料的未来发展方向。