摘要
零折射率(Near-Zero-Index,NZI)媒质因其在电磁波调控中展现出的独特物理特性,近年来成为人工电磁媒质研究的重要方向.与传统材料不同,NZI媒质能够在介电常数或磁导率趋近于零的条件下表现出波长无限拉伸、相速度趋于无穷、传播相位不变等特征,进而呈现“时域振荡、空域静止”的时空解耦特性.这些特性为突破常规器件在尺寸、带宽和形状受限等方面的瓶颈提供了新的物理途径.本文系统回顾了NZI媒质的物理基础、实现机制及典型人工结构形式.首先从物理机理出发,介绍其波长拉伸、超耦合效应与理想能流特征;随后综述了NZI媒质的实现方式,并进一步介绍了近年来发展迅速的“光学掺杂”理论,即通过在NZI媒质中引入异质掺杂体实现等效磁导率的精细调控,从而在亚波长尺度上构建NZI人工电磁媒质.该方法具有参数可调、几何无关和易集成等优势,已成为NZI媒质工程化的重要手段.在应用方面,本文从吸收、传输与辐射三个角度总结了NZI人工电磁媒质的典型功能与性能优势;在吸收方面,利用NZI媒质中的场增强效应、阻抗匹配机制及完美相干吸收,可实现超高灵敏度传感、高效热辐射调控、超薄吸收表面等;在传输方面,利用NZI媒质的超耦合效应、阻抗调控能力与色散工程,可实现任意形状的无反射能量传输、高效率可弯曲互连、多端口功率分配以及多通道频分复用等功能器件;在辐射方面,利用NZI媒质的几何无关性与零相移特性,可实现波前整形、定向辐射与方向图可重构等功能,构建形状无关、高集成度的可调控天线器件.目前,NZI人工电磁媒质仍面临带宽受限、损耗较大与工艺兼容性差等关键挑战.未来发展方向包括:发展宽带低损耗材料体系,实现结构与模式的协同优化;推动力学、热学、量子等多物理场交叉融合,实现与芯片及光学深度集成等.
Near-zero-index(NZI)media have emerged as a significant research direction in artificial electromagnetic(EM)media in recent years due to their unique physical properties in EM wave manipulation.Unlike traditional materials,NZI media can exhibit features such as infinitely stretched wavelength,infinite phase velocity,and unchanged propagation phase under conditions where the permittivity or permeability approaches zero.This leads to a spatiotemporal decoupling characteristic described as“temporal oscillation,spatial stillness”.These properties provide new physical pathways to overcome the bottlenecks of conventional devices in terms of size,bandwidth,and shape constraints.This article systematically reviews the physical fundamentals,implementation mechanisms,and typical NZI metamaterials.Starting from the physical mechanisms,this article introduces their wavelength stretching,supercoupling effects,and ideal power flow characteristics.Subsequently,the implementation methods of NZI media are summarized,and the rapidly developing theory of“photonic doping”is further introduced.This theory involves introducing heterogeneous doping elements into NZI media to achieve fine-tuning of the effective permeability,thereby constructing NZI metamaterials at subwavelength scales.This method offers advantages such as tunable parameters,geometry independence,and ease of integration,making it an important engineering approach for NZI media.In terms of applications,this article summarizes the typical functions and performance advantages of NZI metamaterials from three perspectives:absorption,transmission,and radiation.In absorption,leveraging the field enhancement effects,impedance matching mechanisms,and perfect coherent absorption in NZI media enables ultra-high sensitivity sensing,efficient thermal radiation control,and ultra-thin absorbing surfaces.In transmission,utilizing the supercoupling effects,impedance control capabilities,and dispersion engineering of NZI media enables functional devices such as reflectionless energy transmission of arbitrary shapes,high-efficiency bendable interconnects,multiport power distribution,and multichannel frequency division multiplexing.In radiation,exploiting the geometry independence and zero-phase-shift characteristics of NZI media enables wavefront shaping,directional radiation,and reconfigurable radiation patterns,facilitating the construction of shape-independent,highly integrated tunable antenna devices.Currently,NZI metamaterials still face critical challenges such as limited bandwidth,significant losses,and poor process compatibility.Future development directions include:developing broadband,low-loss material systems to achieve synergistic optimization of structures and modes;promoting interdisciplinary integration across mechanical,thermal,quantum,and other physical fields;and realizing deep integration with chip and optical platforms.
作者
闫雯荻
李越
YAN Wen-di;LI Yue(Department of Electronic Engineering,Tsinghua University,Beijing 100084,China;Beijing National Research Center for Information Science and Technology,Beijing 100084,China;State Key Laboratory of Space Network and Communications,Tsinghua University,Beijing 100084,China)
出处
《电子学报》
北大核心
2025年第11期4157-4170,共14页
Acta Electronica Sinica
基金
国家自然科学基金(No.U22B2016)
国家重点研发计划(No.2021YFA0716601)。
关键词
零折射率媒质
零折射率等效媒质理论
光学掺杂
阻抗匹配
传输线
天线
near-zero-index medium
near-zero-index metamaterials
photonic doping
impedance matching
transmission line
antenna
