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研究人员宣布光子-声子突破

已有 1336 次阅读 2021-10-9 20:23 |个人分类:新科技|系统分类:博客资讯

研究人员宣布光子-声子突破

诸平

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Alexander Khanikaev,  Professor

Fellow of the Optical Society of America

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Topologically distinct photonic crystals (orange and blue) with a layer of hexagonal boron nitride on top enable coupling of topological light and lattice vibrations to form chiral half-light half-vibration excitations, which can be directionally guided along 1D channels in robust manner. Credit: Filipp Komissarenko and Sriram Guddala

据美国纽约城市学院(City College of New York简称CCNY2021108日提供的消息,纽约城市学院的一个研究小组发现了一种将两种不同状态的物质结合起来的新方法(Researchers announce photon-phonon breakthrough)。拓扑光子即光(topological photons—light)与晶格振动(lattice vibrations)也称为声子(phonons)结合在一起,以一种稳健和可控的方式控制它们的传播,这是第一次。相关研究结果于2021108日已经在《科学》(Science)杂志网站发表——S. GuddalaF. KomissarenkoS. KiriushechkinaA. VakulenkoM. LiV. M. MenonA. Alù, A. B. Khanikaev. Topological phonon-polariton funneling in mid-infrared metasurfacesScience, 8 Oct 2021, 3746564: 225-227. DOI: 10.1126/science.abj5488. http://www.science.org/doi/10.1126/science.abj5488

该研究利用了拓扑光子学(topological photonics),这是光子学的一个新兴方向,它利用了数学拓扑领域的基本思想,即在连续变形下改变几何物体的部分时保持不变的守恒量即拓扑不变量(topological invariants)。这种不变量的一个最简单的例子是洞的数量,例如,从拓扑的角度来看,这使得甜甜圈(donut)和马克杯(mug)等价。拓扑性质赋予光子螺旋性(helicity),当光子在传播时自旋,导致独特和意外的特性,如对缺陷的健壮性和沿拓扑截然不同的材料之间界面的单向传播。由于与晶体振动的相互作用,这些螺旋光子可以利用振动引导红外光。

这项工作的意义是广泛的,特别是允许研究人员推进拉曼光谱,这是用来确定分子的振动模式。这项研究也为振动光谱(也称为红外光谱)带来了希望,它可以通过吸收、发射或反射来测量红外辐射与物质的相互作用。这可以用来研究、鉴定和表征化学物质。

该研究的通讯作者、CCNY格罗夫工程学院(CCNY's Grove School of Engineering)的物理学家亚历山大·哈尼卡耶夫(Alexander Khanikaev)说:“我们将螺旋光子(helical photons)与六方氮化硼(hexagonal boron nitride)的晶格振动耦合在一起,创造了一种新的混合物质,称为声子-极化激元(phonon-polaritons)。它一半是光,一半是振动。由于红外光和晶格振动与热有关,我们创造了光和热一起传播的新通道。通常,晶格振动很难控制,引导它们绕过缺陷和尖角(sharp corners)之前是不可能的。”

这种新方法还可以实现定向辐射传热,这是一种通过电磁波散热的能量传递形式。亚历山大·哈尼卡耶夫教授团队的博士后研究员、该论文的第一作者史利南·古达拉(Sriram Guddala)博士补充说:“我们可以为这种混合光和物质激发形式创建任意形状的通道,在我们创建的二维材料中引导它们。这种方法也允许我们改变振动沿这些通道的传播方向,向前或向后,仅仅通过改变入射激光束的偏振方向。有趣的是,当声子极化激元传播时,振动也随着电场旋转。”

上述介绍,仅供参考。欲了解更多信息,敬请注意浏览原文或者相关报道

Coupling light and heat

Understanding of the topological features of bandgaps has provided a route for engineering optical structures that exhibit directional propagation of light and are robust to defects. Guddala et al. combined a silicon-based topological photonic crystal with an atomic monolayer of hexagonal boron nitride (hBN). The topological features of the photonic crystal are coupled to the lattice vibrations of the hBN through the formation of phonon-polaritons. Funneling of helical infrared phonons along arbitrary pathways and across sharp bends provides the possibility of realizing directional heat dissipation along topologically resilient heat sinks. —ISO

Abstract

Topological photonics offers enhanced control over electromagnetic fields by providing a platform for robust trapping and guiding of topological states of light. By combining the strong coupling between topological photons with phonons in hexagonal boron nitride (hBN), we demonstrate a platform to control and guide hybrid states of light and lattice vibrations. The observed topological edge states of phonon-polaritons are found to carry nonzero angular momentum locked to their propagation direction, which enables their robust transport. Thus, these topological quasiparticles enable the funneling of infrared phonons mediated by helical infrared photons along arbitrary pathways and across sharp bends, thereby offering opportunities for applications ranging from Raman and vibrational spectroscopy with structured phonon-polaritons to directional heat dissipation.




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