We derive an effective medium model to characterize the macroscopic electromagnetic response of metallic nanowire arrays embedded in a host dielectric with a Kerr-type nonlinear permittivity function. It is shown that the macroscopic electromagnetic fields are coupled to the conduction current in the nanowires and to an additional quasi-static potential through a system of nonlinear equations. We prove that a weak nonlinearity leads to an electromagnetic response closer to that of an indefinite medium, and to isofrequency contours with increased hyperbolicity. For high-field intensities the negative refraction of electromagnetic waves at an air nanowire material interface is enhanced when the nanowires are embedded in a self-focusing Kerr medium.
Comprehensive Control of Optical Polarization Anisotropy in Semiconducting Nanowires
半导体纳米线的强光致发光偏振各向异性的展示体现了技术承诺和科学挑战。在这里,我们目前的进展,在这两个方面通过研究的随机取向的纳米线合奏材料的光致发光偏振各向异性没有/具有晶体各向异性,小/宽带隙,和III-V/II-VI化学(InP/ZnO纳米线,分别)。极化各向异性的综合控制是通过与共形沉积的Ta 2 O 5(InP和ZnO的介电比分别为9.6:4.41和4.0:4.41)的介电匹配来实现的。介电匹配后,纳米线系综的极化各向异性降低了86%的InP:Ta 2 O 5和84%的ZnO:Ta 2 O 5。
Magnetization reversal mechanism of double-helix nanowires probed by dark-field magneto-optical Kerr effect
TU Wien(维也纳工业大学);University of Loughborough(拉夫堡大学);Instituto de Nanociencia y Materiales de Aragón, CSIC-Universidad de Zaragoza(阿拉贡纳米科学与材料研究所,西班牙科学理事会-萨拉戈萨大学);Synchrotron SOLEIL(SOLEIL同步辐射中心);University of Vienna(维也纳大学);Max Planck Institute for Chemical Physics of Solids(马克斯·普朗克固体化学物理研究所);Hiroshima University(广岛大学)
Photonic band structure and effective medium properties of doubly-resonant core-shell metallo-dielectric nanowire arrays: low-loss, isotropic optical negative-index behavior
Disorder effects in topological insulator nanowires
研究了具有量子化表面子带谱的三维拓扑绝缘体(TI)纳米线作为Majorana束缚态(MBS)器件的主要组成部分。然而,已知这种线具有大浓度$N \sim 10^{19}$ cm $^{-3}$的库仑杂质。据信,只有当随机库仑势$Γ$的长程波动的幅度小于子带隙$Δ$时,MBS器件才能起作用。在这里,我们计算$Γ$最近实验研究的大介电常数(Bi $_{1-x}$ Sb $_x$)$_2$ Te $_{3}$线在小介电常数的环境(无超导体)。我们表明,提供了这样的介电常数的对比度,限制电线内的杂质的电场允许更遥远的杂质,以促进$Γ$,导致$Γ\sim 3Δ$。我们还计算了TI线电阻作为费米能级和载流子浓度的函数,由于散射库仑和中性杂质,并没有发现可观察到的离散子带光谱相关的振荡在$N \gtrsim 10^{18}$ cm $^{-3}$。
在强激光照射下,少层石墨烯表现出由于可饱和吸收和非线性相移的透射率增加。在这里,我们明确区分这两种非线性光学效应,并确定石墨烯的复非线性折射率的实部和虚部。我们发现石墨烯具有巨大的非线性折射率n2=10- 7 cm ~ 2 W ~(-1),比体相石墨烯大9个数量级。我们发现,非线性折射率随激发光通量的增加而减小,但比吸收慢。这表明石墨烯可能是一种非常有前途的非线性介质,为基于石墨烯的非线性光子学铺平了道路。