论文标题

来自银纳米线的聚焦线性偏振光散射:光学自旋效应的实验表征

Focused linearly-polarized light scattering from a silver nanowire: Experimental characterization of optical spin-Hall effect

论文作者

Paul, Diptabrata, Sharma, Deepak K., Kumar, G. V. Pavan

论文摘要

自旋轨道相互作用(SOI)是一组亚波长的光学现象,其中自旋和空间光自由度本质上是耦合的。 SOI的独特示例之一,光(SHEL)是广泛研究的领域,并在自旋控制的光子设备以及旋转式和旋转的新兴领域中进行了潜在应用。在这里,我们报告了我们对SHEL的实验研究,这是由于聚焦线性两极化的高斯和Hermite-Gaussian($ \ textrm {hg} _ {10} $)的前向散射,来自银纳米线(AGNW)。分析散射光的极化时,获得自旋依赖性的抗对称强度模式。通过计算远场纵向自旋密度($ S_3 $)获得相应的旋转信号。此外,通过比较$ s_3 $分布,与高斯光束相比,发现了$ \ textrm {hg} _ {10} $ beam的旋转信号的显着增强。对客观镜头焦平面上光场的研究揭示了纵向旋转场的产生,这是效应的主要原因。实验结果通过三维数值模拟证实。结果可以更好地理解SOI,并且可以直接对芯片尺度旋转辅助光子设备产生影响。

Spin-orbit interactions (SOI) are a set of sub-wavelength optical phenomenon in which spin and spatial degrees of freedom of light are intrinsically coupled. One of the unique example of SOI, spin-Hall effect of light (SHEL) has been an area of extensive research with potential applications in spin controlled photonic devices as well as emerging fields of spinoptics and spintronics. Here, we report our experimental study on SHEL due to forward scattering of focused linearly polarized Gaussian and Hermite-Gaussian ($\textrm{HG}_{10}$) beams from a silver nanowire (AgNW). Spin dependent anti-symmetric intensity patterns are obtained when the polarization of the scattered light is analysed. The corresponding spin-Hall signal is obtained by computing the far-field longitudinal spin density ($s_3$). Furthermore, by comparing the $s_3$ distributions, significant enhancement of the spin-Hall signal is found for $\textrm{HG}_{10}$ beam compared to Gaussian beam. The investigation of the optical fields at the focal plane of the objective lens reveals the generation of longitudinally spinning fields as the primary reason for the effects. The experimental results are corroborated by 3-dimensional numerical simulations. The results lead to better understanding of SOI and can have direct implications on chip-scale spin assisted photonic devices.

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