共查询到17条相似文献,搜索用时 406 毫秒
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超构光学为平面光学器件的发展提供了新的思路与方向。超构器件由亚波长人工纳米结构组成,能在二维平面上实现对入射光的振幅、相位和偏振的操纵。研究人员已经发展了多种超构表面技术,将其用于满足各式各样的光学需求。本文首先回顾了超构器件的前沿研究与技术发展现状,介绍了超构器件的广义设计流程,并以连续宽带消色差超构透镜为例进行逐步说明,帮助读者理解;然后,展示了多种超构器件加工方法,包括直写刻蚀、图案转移刻蚀和混合图案刻蚀等,进一步讨论了超构器件在成像应用中的发展,包括偏振成像、光场成像、光学感测以及生物成像等;最后,进行了总结,并对超构器件未来的发展提出了见解与展望。 相似文献
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作为波的本性之一,衍射是现代物理学的重要研究内容.衍射导致自由空间中波的能量不能被无限小地聚集,从而为成像、光刻、光存储、光波导等技术设定了一个原理性的障碍——衍射极限.对于电磁波和光波而言,尽管通过提高介质的折射率可以压缩衍射效应,但由于自然界中材料的折射率有限,该方法存在很大限制.近年来,随着表面等离子体光学的兴起,表面等离子体在超越传统衍射极限方面的能力和应用前景受到了学术界的关注.本文从亚波长电磁学的角度出发,介绍衍射极限研究的历史,综述了突破衍射极限的理论方法.首先,利用金属介质表面等离子体激元的短波长特性,可将等效波长压缩一个数量级以上,在纳米尺度实现光波的聚焦或定向传输;更进一步,通过人为设计超构材料和超构表面,利用结构化金属和介质中的局域谐振、耦合等特殊电磁响应,可实现亚波长局域相位调制、超宽带色散调控、近完美吸收、光子自旋轨道耦合等,从而突破传统理论的诸多局限,为下一代电磁学和光学功能器件奠定重要基础. 相似文献
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自从电磁波被发现和应用以来,利用各种材料或者结构调节电磁波的辐射行为、构造高性能的电磁辐射器件一直是研究人员的追求目标.经过百余年的发展,电磁辐射器件的方向性提高、带宽拓展等技术逐渐达到瓶颈.受自然材料电磁特性的限制,微带天线、喇叭天线等传统电磁辐射器件存在体积重量大、工作带宽窄、无法快速动态调控等缺陷,难以满足日益发展的通信技术的需求.近年来出现的亚波长结构可在深度亚波长尺度下调控电磁波的传输行为,出现了多种奇异的电磁现象,完善了传统的电磁学理论,在一定程度上突破了传统材料电磁特性的限制,形成全新的电磁辐射技术,有效解决了传统天线存在的口径大、厚度高、带宽窄等难题,促进了电磁学、光子学、材料学等领域的发展.这种基于超构材料的新型天线可以被称为超构天线,具有高方向性、低副瓣、超宽带、可重构等传统天线难以实现的功能.本文主要回顾了近年来基于亚波长超构材料的超构天线技术的发展现状和取得的成果,介绍了超构材料在亚波长尺度下对电磁波振幅、相位、偏振态等的衍射调控机理,以及在此基础上形成的新型辐射器件,例如相控阵天线、高方向性天线、低雷达散射截面天线,基于亚波长结构的多种偏振调控器件及其在天线中的应用等.在衍射极限尺度下,这种亚波长结构的调控行为可有效提升电磁辐射器件的方向性、带宽,并可重构天线的工作频率、偏振态等性能. 相似文献
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The geometric phase of light has been demonstrated in various platforms of the linear optical regime, raising interest both for fundamental science as well as applications, such as flat optical elements. Recently, the concept of geometric phases has been extended to nonlinear optics, following advances in engineering both bulk nonlinear photonic crystals and nonlinear metasurfaces. These new technologies offer a great promise of applications for nonlinear manipulation of light. In this review, we cover the recent theoretical and experimental advances in the field of geometric phases accompanying nonlinear frequency conversion. We first consider the case of bulk nonlinear photonic crystals, in which the interaction between propagating waves is quasi-phase-matched, with an engineerable geometric phase accumulated by the light. Nonlinear photonic crystals can offer efficient and robust frequency conversion in both the linearized and fully-nonlinear regimes of interaction, and allow for several applications including adiabatic mode conversion, electromagnetic nonreciprocity and novel topological effects for light. We then cover the rapidly-growing field of nonlinear Pancharatnam-Berry metasurfaces, which allow the simultaneous nonlinear generation and shaping of light by using ultrathin optical elements with subwavelength phase and amplitude resolution. We discuss the macroscopic selection rules that depend on the rotational symmetry of the constituent meta-atoms, the order of the harmonic generations, and the change in circular polarization. Continuous geometric phase gradients allow the steering of light beams and shaping of their spatial modes. More complex designs perform nonlinear imaging and multiplex nonlinear holograms, where the functionality is varied according to the generated harmonic order and polarization. Recent advancements in the fabrication of three dimensional nonlinear photonic crystals, as well as the pursuit of quantum light sources based on nonlinear metasurfaces, offer exciting new possibilities for novel nonlinear optical applications based on geometric phases. 相似文献
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电磁超表面属于超材料的一种,是由许多亚波长纳米结构单元组成的二维功能性平面结构.根据惠更斯原理,超表面阵列可以任意调控光波的相位、振幅和偏振.与传统器件相比,基于这种超材料设计的光学功能器件最大的优势是其具有极薄的厚度.本文首先介绍了广义斯涅耳定律以及纳米单元结构调控相位的基本原理,重点归纳了电磁超表面在透镜成像技术方面的研究进展,包括等离子体超表面、全介质超表面以及金属/介质混合式超表面在成像方面的应用,最后指出了超表面在成像方面尚未解决的前沿问题以及与实际应用接轨的重要问题,希望能为以后的深入研究提供一定的参考和借鉴. 相似文献
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Guangzhou Geng 《中国物理 B》2022,31(12):124207-124207
The photonic spin Hall effect has attracted considerable research interest due to its potential applications in spin-controlled nanophotonic devices. However, realization of the asymmetrical photonic spin Hall effect with a single optical element is still a challenge due to the conjugation of the Pancharatnam-Berry phase, which reduces the flexibility in various applications. Here, we demonstrate an asymmetrical spin-dependent beam splitter based on a single-layer dielectric metasurface exhibiting strong and controllable optical response. The metasurface consists of an array of dielectric nanofins, where both varying rotation angles and feature sizes of the unit cells are utilized to create high-efficiency dielectric metasurfaces, which enables to break the conjugated characteristic of phase gradient. Thanks to the superiority of the phase modulation ability, when the fabricated metasurface is under normal incidence with a wavelength of 1550 nm, the left-handed circular polarization (LCP) light exhibits an anomalous refraction angle of 28.9°, while the right-handed circular polarization (RCP) light transmits directly. The method we proposed can be used for the flexible manipulation of spin photons and has potentials in high efficiency metasurfaces with versatile functionalities, especially with metasurfaces in a compact space. 相似文献
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近年来,基于超表面材料的研究发现了很多新的光学现象,其中几何相位调制是最具吸引力的方向之一。笔者介绍了超表面材料用于光波相位精密操控方面的研究,包括电磁响应的各向异性、电磁共振等机理研究、以及一系列新概念光器件。研究表明,基于金纳米棒超表面材料制造的计算全息片,能够在波长为630 nm~1 050 nm的宽带范围内高效工作,且在波长825 nm处的衍射效率超过80%;基于硅材料超表面材料制造的光分束器,能够在远场形成衍射角为59°×59°的4×4个均匀点阵,且其衍射效率在波长为1 530 nm~1 565 nm的范围内超过50%;基于硅材料超表面材料制造的偏振分离器,其在纳米棒长轴方向的反射率高达98.5%,在短轴方向透过率达到94.7%,且仅需通过调节纳米棒的宽度,就可以在波长为1 460 nm~1 625 nm的宽带范围内任意选择峰值反射波长。研究结果表明,基于几何相位调制机理的超表面材料在具备连续、任意、精密、高效的相位操控等优点的同时,在制造上却仅需要简单的二台阶微纳光学工艺条件,可用于打造新一代高性能、芯片级的光电子元器件,在光纤通信、军事国防、工业及消费电子等领域得到重要应用。 相似文献
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Two-dimensional materials-decorated microfiber devices for pulse generation and shaping in fiber lasers
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Two-dimensional(2D) materials have been regarded as a promising nonlinear optical medium for fabricating versatile optical and optoelectronic devices. Among the various photonic applications, the employment of 2D materials as nonlinear optical devices such as saturable absorbers for ultrashort pulse generation and shaping in ultrafast lasers is one of the most striking aspects in recent years. In this paper, we review the recent progress of 2D materials based pulse generation and soliton shaping in ultrafast fiber lasers, and particularly in the context of 2D materials-decorated microfiber photonic devices. The fabrication of 2D materials-decorated microfiber photonic devices, high performance mode-locked pulse generation, and the nonlinear soliton dynamics based on pulse shaping method are discussed. Finally, the challenges and the perspective of the 2D materials-based photonic devices as well as their applications are also discussed. 相似文献
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Quadratic nonlinear photonic crystals are materials in which the second order susceptibility χ(2) is spatially modulated while the linear susceptibility remains constant. These structures are significantly different than the more common photonic crystals, in which the linear susceptibility is modulated. Nonlinear processes in nonlinear photonic crystals are governed by the phase matching requirements, which are determined by the reciprocal lattice of these crystals. Therefore, the modulation of the nonlinear susceptibility enables to engineer the spatial and spectral response in various three‐wave mixing processes. It enables to support the efficient generation of new optical frequencies at multiple directions. We analyze three wave mixing processes in nonlinear photonic crystals in which the modulation is either periodic, quasi‐periodic, radially symmetric or even random. We discuss both one‐dimensional and two‐dimensional modulations. In addition to harmonic generations, we outline several new possibilities for all‐optical control of the spatial and polarization properties of optical beams in specially designed nonlinear photonic crystals. 相似文献
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超表面是由亚波长结构组成的超薄人工表面,对电磁波具有突出的调控能力。近年来,因其在非线性效应增强方面的巨大潜力,超表面引起了人们越来越多的重视。具有现场可编程能力和时空信息调制能力的时空编码数字超表面可精准、高效地操控非线性电磁效应和电磁信息,因此成为非线性超表面的一种新模式。文章首先介绍时空编码数字超表面的基本概念,重点讨论近几年在非线性电磁调控方面的研究进展,包括谐波生成、电磁参数控制和非线性波前调控等相关工作。最后,对时空编码数字超表面面临的挑战及未来的发展趋势进行了总结和展望。 相似文献