太赫兹超材料及其成像应用研究进展

电磁超材料因具有特殊的物理性质以及在电磁波操控方面的重要应用而备受关注。本文综述了太赫兹超材料及其成像应用的研究进展:首先介绍了太赫兹超材料的研究概况,重点讨论了可调谐与可重构太赫兹超材料、太赫兹数字编码与现场可编程超材料的研究进展;在此基础上,阐述了太赫兹超材料在成像领域的应用,包括基于超表面透镜、超材料吸波器、可重构超表面和现场可编程超表面的太赫兹成像技术;最后讨论了太赫兹超材料及其成像应用发展趋势。功能可重构及智能化将是太赫兹超材料的重要发展方向,而新兴的信息超材料融合了超材料与信息技术也将使太赫兹成像更加高效便捷。     

高效光学可调谐介质超表面研究进展

自超表面(超薄亚波长厚度超材料)被提出之后,其基础材料经历了从金属、混合介质再到全介质材料的更迭.传统超表面功能单一,在实际应用中存在局限性,因此,研究者们把目标放在了动态可调谐的超表面上.本文介绍了具有高效光传输特性的混合介质和全介质的可调谐超表面的一些理论基础,并对近期的研究进展进行了综述,全介质型可调谐超表面又分为材料调谐和物理调谐两部分.在红外和太赫兹波段,主要介绍了锗-锑-碲化合物(Ge2 Sb2 Te5,GST)、VO2、石墨烯、液晶、砷化镓等一些常用材料的可调谐超表面的研究进展,最后,给出了对可调谐超表面未来发展的一些个人看法.     

金属纳米结构的表面等离子体光学研究获得系列进展

金属纳米结构的表面等离子体光学在光催化、纳米集成光子学、光学传感、生物标记、医学成像、太阳能电池,以及表面增强拉曼光谱（SERS）等领域有广泛的应用前景,这些功能和金属纳米结构与光相互作用时产生的表面等离子体共振密切相关。最近,中科院物理研究所光物理实验室李志远研究组,     

纳米材料作为增强基底在表面增强红外技术中的研究

吸附在金属薄膜或金属纳米颗粒表面的分子的红外吸收强度会发生很大的提高,这种现象称为表面增强红外,它与表面增强拉曼具有类似的增强机理,能极大降低红外检测的下限。简单介绍了表面增强红外光谱特点、增强机制、测试方式及其应用,总结了近10余年纳米材料作为红外增强基底在表面增强红外光谱中的研究,并展望其发展前景。     

超表面的电磁特性研究进展

超表面由于具有自然界不存在的独特电磁特性而引起了人们极大的兴趣,它是占有更少物理空间,提供更小损耗,更容易被制造的一类超材料。简要介绍了超表面的概念和背景,并着重阐述了超表面结构在微波段、太赫兹波段以及光频段的模拟计算及实验研究进展。这些超表面在微波、光波、光电子器件中具有潜在的应用价值。     

二维材料MXenes在传感领域的应用研究进展

二维(2D)材料MXenes独特的结构、组成和物理化学特性,使其成为继石墨烯之后2D材料研究领域又一种"明星"材料.MXenes的应用范围从机械、光学、电子、储能等领域扩展到生物医学、环境保护等.这主要是由于其具有大比表面积、高导电性、丰富的表面功能基团、良好的生物相容性,以及可利用各种聚合物或纳米颗粒进行表面功能化,使其有望应用于精准的生物传感、有毒气体和液体污染物传感监测平台.目前,MXenes材料在传感领域的研究主要集中于电流型生物传感、生物/气体电阻传感和压电传感等.在生物电化学传感中,MXenes材料主要用作蛋白质、生物酶、生物发光材料等的固定化基质,以利用其大比表面积、高导电性的特性,提高电子传质效率和速率,从而达到提高传感灵敏度、降低检测限的目的;生物/气体电阻传感是基于MXenes材料对外来吸附分子(生物分子或气体分子)造成的电导率扰动的灵敏性反映,而MXenes材料对外来生物分子或气体分子的吸附是基于其丰富的功能基团(主要为-OH、-F、-O、-Cl等)与这些分子之间的相互作用;压电传感方面的研究主要集中于便携式或可穿戴式压电传感器,MXenes受应力作用,其层间距发生变化,导致其电导率发生变化而产生电信号.可见,在传感器的应用中,人们利用的是MXenes材料的大比表面积和导电性以及表面功能基团.但是,MXenes材料的导电性受表面功能基团的影响,这些基团在一定程度上会降低MXenes的导电性,甚至某些基团使其变为半导体,这不利于传感器高导电性的要求.事实上,功能基团和高电导率是一对矛盾体,研究工作需要在两者之间寻找最佳平衡点.另外,不同的功能基团对不同元素类型的MXenes材料的导电性影响也存在差别.因此,研究者在研究利用进一步的功能化修饰电极(例如修饰贵金属纳米粒子、碳纳米管等)来克服电导率的问题的同时,也在积极寻求更适合传感的不同元素类型的MXenes材料.本文简要概述了MXenes材料的制备、结构、性能研究进展,重点综述了为生物医学、环境保护应用而设计的MXenes传感器的构建及其最新研究进展,包括电流型生物传感、可穿戴式生物传感、MXenes还原电化学传感、生物电阻传感、气体电阻传感、压电/应变传感等.本文还讨论了MXenes材料在传感领域应用面临的困难和挑战.希望本文能在MXenes传感器的开发及应用中为研究者提供有益的指导和帮助.     

武汉光电国家实验室在石墨烯阵列中的增强吸收研究方面取得新进展

<正>石墨烯作为一种新型二维材料,具有电导率可控、电子迁移率高和易于与其它光学器件集成的特点,近年来吸引了研究者的广泛关注。在可见光波段,石墨烯具有饱和吸收特性,仅能吸收2.3%的入射光能,限制了其在光电子器件上的应用。武汉光电国家实验室超快光学团队陆培祥教授、王兵教授、博士生柯少林等针对十字形石墨烯阵列结构进行了系统的数值模拟。研究表明,在红外和太赫兹波段,阵列结构中产生的表面等离激元共振可以有效地     

表面等离子共振氢气传感研究进展

基于表面等离子共振原理的光学氢气传感已经成为氢气传感技术研究的热点.表面等离子共振传感器具有安全可靠、灵敏度高、实时性好、便于分布式多点检测等优点,在氢气泄漏检测方向具有广阔的应用前景.本综述介绍了表面等离子共振氢气传感器的三种主要结构类型:棱镜耦合结构,光栅耦合结构和光纤耦合结构的检测原理、典型结构及其研究进展;重点论述了表面等离子共振氢气传感技术中氢敏感膜系的研究现状和技术难题;分析了目前表面等离子共振氢气传感实际应用所面临的瓶颈,并对未来的研究方向进行了展望.结合实际,提出了开发基于光纤微结构和纳米材料的新型氢气传感器件,并且将传感原理延伸至局域表面等离子体共振,表面等离子体共振成像等新兴技术.     

太赫兹脉冲焦平面成像技术的发展与应用

作为太赫兹技术中的重要组成部分,太赫兹脉冲焦平面成像一经问世就引起了行业内的广泛关注,人们引入了各种方法去提升此成像技术的测量性能,同时也尝试将此成像技术应用于不同的工业和基础研究领域。本文综述了近年来人们对太赫兹脉冲焦平面成像的技术改良和应用研究,包括提升成像系统的空间分辨率、信噪比、信息获取能力,以及将此成像技术应用于光谱识别检测、超表面器件功能验证、太赫兹特殊光束测量、太赫兹表面波观测等,希望该综述能够推动太赫兹脉冲焦平面成像的进一步技术革新和应用拓展。     

细菌视紫红质在生物传感器中的应用进展

生物传感器是生物敏感材料、理化换能器与电信号放大装置等多学科交叉的综合集成技术装置.典型的生物传感器以特异性感知的生物活性材料作为敏感元件,结合基于微电子器件的物理化学换能器和调理电路,实现生物敏感信息的电信号转换及放大.换能器的灵敏度、抗干扰能力等因素直接影响生物传感器的性能.从嗜盐菌中提取的细菌视紫红质是一种具有良好光敏特性的生物材料,可直接将光信号转化成电信号,从而实现将敏感元件和换能器合二为一的功能,已广泛应用于多种生物传感器中.细菌视紫红质的感光灵敏度和稳定性适用于开发具有颜色灵敏度的光传感器,最早的应用方向是人工视网膜;其光敏感和换能一体化特性可实现使用单个传感元件进行光学运动检测的功能,应用可扩展到运动传感领域.除了在视觉传感领域的应用,细菌视紫红质在病原体检测、水体pH检测、细胞膜电位检测等领域均表现出良好的灵敏性、稳定性和特异性.其不仅在生物传感领域具有应用价值,而且为半导体传感方法的研究提供了新途径.本文在简述细菌视紫红质的质子泵和光电响应特性等基本功能的基础上,阐述了细菌视紫红质构建生物传感器的应用进展,分析了不同传感器的特点,以期为细菌视紫红质的机理及其应用研究提供参考.     

Hybrid Lead Halide Perovskites for Ultrasensitive Photoactive Switching in Terahertz Metamaterial Devices

The recent meteoric rise in the field of photovoltaics with the discovery of highly efficient solar‐cell devices is inspired by solution‐processed organic–inorganic lead halide perovskites that exhibit unprecedented light‐to‐electricity conversion efficiencies. The stunning performance of perovskites is attributed to their strong photoresponsive properties that are thoroughly utilized in designing excellent perovskite solar cells, light‐emitting diodes, infrared lasers, and ultrafast photodetectors. However, optoelectronic application of halide perovskites in realizing highly efficient subwavelength photonic devices has remained a challenge. Here, the remarkable photoconductivity of organic–inorganic lead halide perovskites is exploited to demonstrate a hybrid perovskite–metamaterial device that shows extremely low power photoswitching of the metamaterial resonances in the terahertz part of the electromagnetic spectrum. Furthermore, a signature of a coupled phonon–metamaterial resonance is observed at higher pump powers, where the Fano resonance amplitude is extremely weak. In addition, a low threshold, dynamic control of the highly confined electric field intensity is also observed in the system, which could tremendously benefit the new generation of subwavelength photonic devices as active sensors, low threshold optically controlled lasers, and active nonlinear devices with enhanced functionalities in the infrared, optical, and the terahertz parts of the electromagnetic spectrum.     

Chalcogenide Phase Change Material for Active Terahertz Photonics

The strikingly contrasting optical properties of various phases of chalcogenide phase change materials (PCM) has recently led to the development of novel photonic devices such as all‐optical non‐von Neumann memory, nanopixel displays, color rendering, and reconfigurable nanoplasmonics. However, the exploration of chalcogenide photonics is currently limited to optical and infrared frequencies. Here, a phase change material integrated terahertz metamaterial for multilevel nonvolatile resonance switching with spatial and temporal selectivity is demonstrated. By controlling the crystalline proportion of the PCM film, multilevel, non‐volatile, terahertz resonance switching states with long retention time at zero hold power are realized. Spatially selective reconfiguration at sub‐metamaterial scale is shown by delivering electrical stimulus locally through designer interconnect architecture. The PCM metamaterial also features ultrafast optical modulation of terahertz resonances with tunable switching speed based on the crystalline order of the PCM film. The multilevel nonvolatile, spatially selective, and temporally tunable PCM metamaterial will provide a pathway toward development of novel and disruptive terahertz technologies including spatio‐temporal terahertz modulators for high speed wireless communication, neuromorphic photonics, and machine‐learning metamaterials.     

吸波超材料研究进展

吸波超材料由于其独特的电磁特性,在过去十几年内成为吸波功能材料领域的研究热点。本文通过对近些年吸波超材料报道的归纳总结,对吸波超材料的研究进展进行介绍。经过多年来的发展,吸波超材料从最初的单一功能窄频段吸波特性逐渐向宽频带、宽角度入射、可智能调节等多功能方向发展,而在吸波频段的研究也由微波频段扩展至太赫兹、近红外、可见光等频段。对不同类型的吸波超材料分别进行介绍,对于不同特点吸波超材料的制备、设计方法和工作原理进行总结,最后对吸波超材料的发展方向进行了展望。      

A Metamaterial Analog of the Ising Model

The interaction between microscopic particles is always a fascinating and intriguing area of science. Direct interrogation of such interactions is often difficult. Structured electromagnetic systems offer a rich toolkit for mimicking and reproducing the key dynamics that govern the microscopic interactions, and thus provides an avenue to explore and interpret the microscopic phenomena. In particular, metamaterials offer the freedom to artificially tailor light–matter coupling and to control the interaction between unit cells in the metamaterial array. Here, a terahertz metamaterial that mimics spin‐related interactions of microscopic particles in a 2D lattice via complex electromagnetic multipoles scattered within the metamaterial array is demonstrated. Fano resonances featured by distinct mode properties due to strong nearest‐neighbor interactions are discussed, which draw parallels with the 2D Ising model. Interestingly, a phase transition from single Fano resonance to hyperfine splitting of the Fano spectrum is observed by manipulating the 2D interactions without applying external magnetic or electric fields, which provides a potential multispectral platform for applications in super‐resolution imaging, biosensing, and selective thermal emission. The dynamic approach to reproduce static interaction between microscopic particles will enable more profound significance in exploring the unknown physical world by the macroscopic analogs.     

Emerging Trends in Terahertz Metamaterial Applications

The terahertz spectrum of electromagnetic waves is finding its position in various applications of day to day life because of its unique properties, including the penetration through opaque materials. Naturally occurring materials in this range are rare due to the display of a natural breakpoint of both electric, and magnetic resonances in these materials. However recent advances in artificially engineered materials, which show resonance in this region are able to harness desirable properties in the terahertz region. In this paper, terahertz design and fabrication issues have been explored along with their applications. A brief review of metamaterial terahertz applications has been carried out including metamaterial absorbers, filters, modulators, switches, lenses, and cloaking structures. The various patterns of metamaterial unit cells are discussed elaborately along with the possibility of flexible active terahertz structures.     

Bilayer fractal structure with multiband left-handed characteristics

We present a bilayer fractal structure for the realization of multiband left-handed metamaterial at terahertz frequencies. The structure is composed of metallic H-fractal pairs separated by a dielectric layer. The electromagnetic properties of periodic H-fractal pairs have been investigated by numerical simulation. The period in the propagation direction is extremely small as compared to the wavelength at the operational frequency. Under the electromagnetic wave normal incidence, the material exhibits negative refraction simultaneously around the frequencies of 0.10 and 0.15 THz for parallel polarization, and around the frequencies of 0.19 and 0.38 THz for perpendicular polarization. The design provides a left-handed metamaterial suitable for multiband and compact devices at terahertz frequencies.     

Soft Computing for Terahertz Metamaterial Absorber Design for Biomedical Application

The terahertz region of the electromagnetic spectrum plays a vital role in biomedical imaging because of its sensitivity to vibrational modes of biomolecules. Advances in broadband terahertz imaging have been emerging in the field of biomedical spectroscopy. Biomedical imaging is used to distinguish between the infected (cancer) and the non-infected tissue, which requires broad band and highly efficient radar absorbing material (RAM) designs (to obtain high resolution image of the tissue). In this paper, a metamaterial broadband RAM design is proposed towards biomedical spectroscopy applications in the THz region. The particle swarm optimization (PSO) algorithm is used for the design and optimization of the RAM, which enhances the absorption to nearly 99.32% at the required operational frequency.     

Graphene‐Based Biosensors: Going Simple

The main properties of graphene derivatives facilitating optical and electrical biosensing platforms are discussed, along with how the integration of graphene derivatives, plastic, and paper can lead to innovative devices in order to simplify biosensing technology and manufacture easy‐to‐use, yet powerful electrical or optical biosensors. Some crucial issues to be overcome in order to bring graphene‐based biosensors to the market are also underscored.     

Enhanced THz absorption of graphene cavity-based electromagnetic metamaterial structures

ABSTRACT

We investigate THz absorption characteristics of graphene cavity-based electromagnetic metamaterial structures by using the conductivity characteristic matrix method. We demonstrate that the proposed structure can obtain ideal terahertz absorption due to the strong localization of photons in the defect layer of the electromagnetic metamaterial structure. The THz absorption can be continuously adjusted from 0% to 100% by controlling the chemical potential of graphene through a gate voltage. The maximum THz absorption value can be tailored by adjusting the incident angle or the period number of the two PCs with respect to the graphene layer. The position of the THz absorption peak can be adjusted by changing the thickness ratio of the layers constituting the electromagnetic metamaterial structure. Our proposal may have potentially important applications in photodetectors, saturable absorbers, and photovoltaics.