Nano Letters
Surface Plasmon-Mediated Nanoscale Localization of Laser-Driven sub-Terahertz Spin Dynamics in Magnetic Dielectrics
Alexander L. Chekhov, Alexander I. Stognij, Takuya Satoh,Tatiana V. Murzina, Ilya Razdolski, and Andrzej Stupakiewicz
Nano Letters 2018 18 (5), 2970-2975
Abstract: We report spatial localization of the effective magnetic field generated via the inverse Faraday effect employing surface plasmon polaritons (SPPs) at Au/garnet interface. Analyzing both numerically and analytically the electric field of the SPPs at this interface, we corroborate our study with a proof-of-concept experiment showing efficient SPP driven excitation of coherent spin precession with 0.41 THz frequency. We argue that the sub diffractional confinement of the SPP electric field enables strong spatial localization of the SPP-mediated excitation of spin dynamics. We demonstrate two orders of magnitude enhancement of the excitation efficiency at the surface plasmon resonance within a 100 nm layer of a dielectric garnet. Our findings broaden the horizons of ultrafast spin-plasmonics and open pathways toward nonthermal optomagnetic recording on the nanoscale.
摘要：利用表面等离子体激元（SPPs）的逆法拉第效应，在金/石榴石界面处可以产生有效磁场的空间定位。概念验证实验显示了高效SPP驱动的相干自旋进动激励，具有0.41THz的频率，通过数值和理论方法分析SPP在这个界面处的电场，我们的研究得到了证实。我们认为，SPP电场的亚绕射限制导致SPP介导的自旋激发具有很强的空间定位特性。我们在100nm的石榴石介电层内的表面等离子体共振处，把激发效率提高了两个数量级。我们的研究结果开拓了超快自旋-等离子体激元的研究范围，并为纳米尺度的(非热)光磁效应存储开辟了新道路。
https://pubs.acs.org/doi/10.1021/acs.nanolett.8b00416
编辑：Xiao Fang
Nature Communications
Continuous-wave highly-efficient low-divergence terahertz wire lasers
Simone Biasco, Katia Garrasi, Fabrizio Castellano, Lianhe Li, Harvey E. Beere, David A. Ritchie, Edmund H. Linfield, A. GilesDavies & Miriam S. Vitiello
Nature Communications volume 9, Article number: 1122 (2018)
Abstract: Terahertz (THz) quantum cascade lasers(QCLs) have undergone rapid development since their demonstration, showing high power, broad-tunability, quantum-limited linewidth, and ultra-broadband gain. Typically, to address applications needs, continuous-wave(CW) operation, low-divergent beam profiles and fine spectral control of the emitted radiation, are required. This, however, is very difficult to achieve in practice. Lithographic patterning has been extensively used to this purpose(via distributed feedback (DFB), photonic crystals or microcavities), to optimize either the beam divergence or the emission frequency, or, both of them simultaneously, in third-order DFBs, via a demanding fabrication procedure that precisely constrains the mode index to 3. Here, we demonstrate wire DFB THz QCLs, in which feedback is provided by a sinusoidal corrugation of the cavity, defining the frequency, while light extraction is ensured by an array of surface holes. This new architecture, extendable to a broad range of far-infrared frequencies, has led to the achievement of low-divergent beams(10°), single-mode emission, high slope efficiencies (250 mW/A), and stable CW operation.
摘要：自提出相关概念后，太赫兹（THz）量子级联激光器（QCLs）经历了快速的发展，表现出高功率、宽调谐性、有限量子线宽和超宽带增益的良好特性。通常，实际应用中需要辐射源工作连续波（CW）模式、具有低发散射束轮廓特性并可以对发射辐射光谱的精细控制。但这在实践中很难实现。为优化光束发散或发射频率，平版印刷刻蚀已被广泛应用（通过分布式反馈（DFB），光子晶体或微腔），或者通过精确限制模式系数为3的加工工艺在三阶分布式反馈中同时优化二者。本文提出线型分布式反馈太赫兹量子级联激光器，其中空腔的正弦波提供反馈并确定频率，同时表面孔阵列确保了光萃取。这种新结构可扩展到远红外波段，从而实现低射束（10°），单模发射，高单位效率（250 mW / A）和稳定的连续波操作。
https://www.nature.com/articles/s41467-018-03440-4
编辑：Xiao Cao
Scientific Reports
Terahertz-driven polymerization of resists in nanoantennas
Woongkyu Park, Youjin Lee, Taehee Kang, Jeeyoon Jeong & Dai-Sik Kim
Scientific Reports volume 8, Article number: 7762 (2018)
Abstract: Plasmon-mediated polymerization has been intensively studied for various applications including nanolithography, near-field mapping, and selective functionalization. However, these studies have been limited from the near-infrared to the ultraviolet regime. Here, were port a resist polymerization using intense terahertz pulses and various nanoantennas. The resist is polymerized near the nanoantennas, where giant field enhancement occurs. We experimentally show that the physical origin of the cross-linking is a terahertz electron emission from the nanoantenna, rather than multiphoton absorption. Our work extends nano-photochemistry into the terahertz frequencies.
摘要：等离子体介导的聚合已被深入研究用于各种应用，包括纳米光刻，近场制图和可选择功能化。 然而，这些研究一直受到近红外到紫外线区域的限制。在这里，我们报告了使用强太赫兹脉冲和各种纳米天线的抗蚀剂聚合。 抗蚀剂在纳米天线附近聚合，从而使场强得到显著增强。 我们通过实验证明，这种交联现象是源于纳米天线的太赫兹电子发射，而不是多光子吸收。我们的工作将纳米光化学扩展到太赫兹频率。
https://www.nature.com/articles/s41598-018-26214-w
编辑：Xiao Kong
Optics Express
Twenty years of terahertz imaging
Daniel M. Mittleman
Optics Express Vol. 26, Issue 8, pp. 9417-9431 (2018)
Abstract: The birth of terahertz imaging approximately coincides with the birth of the journal Optics Express. The 20th anniversary of the journal is therefore an opportune moment to consider the state of progress in the field of terahertz imaging. This article discusses some of the compelling reasons that one may wish to form images in the THz range, in order to provide a perspective of how far the field has come since the early demonstrations of the mid-1990’s. It then focuses on a few of the more prominent frontiers of current research, highlighting their impacts on both fundamental science and applications.
摘要：太赫兹成像几乎与期刊《光学快报》同时诞生。值此期刊成立20周年之际，正是一个很好的时机来思考一下太赫兹成像领域的进展。本文探讨了一些为什么要在太赫兹频段成像的有力理由，也为这个领域自20世纪90年代中期以来的进展提供了一个观点。然后，本文聚焦于当前研究中的几个更为突出的前沿，突出了他们在基础科学和应用中的影响。
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-8-9417#
编辑：Xiao Shan
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