Ghaffari Abbas, Kashani Somayeh, Li Jiazhen, Gkoupidenis Paschalis, Riehn Robert, Gu Qing
Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States.
Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, United States.
ACS Nanosci Au. 2025 May 8;5(4):306-313. doi: 10.1021/acsnanoscienceau.5c00031. eCollection 2025 Aug 20.
Plasmonic polarization conversion offers significant advantages over conventional methods, including a smaller device footprint and easier integration into photonic circuits. In this work, we numerically and experimentally investigate the polarization conversion properties of a plasmonic double-hole structure surrounded by circular nanograting, i.e., a bull's eye antenna. Using a combination of polarimetric imaging via back focal plane (BFP) microscopy and Stokes parameter analysis, we demonstrate the functionality of our structure as a miniature on-chip polarization converter. Our results show that this nanostructure enables complex polarization transformations, including converting linear to circular polarization and vice versa. Polarization conversion efficiency is found to be dependent on the periodicity of the circular gratings and is particularly pronounced in the central region of Fourier space. Moreover, strong asymmetric scattering leads to distinctive patterns in the Stokes parameters across various incident polarization states. This work provides insights into the plasmonic manipulation of light polarization at the nanoscale with potential applications in miniature on-chip polarization convertors, polarization-controlled emitters, and advanced sensing technologies.
表面等离激元偏振转换比传统方法具有显著优势，包括更小的器件尺寸以及更易于集成到光子电路中。在这项工作中，我们通过数值模拟和实验研究了由圆形纳米光栅包围的表面等离激元双孔结构（即靶心天线）的偏振转换特性。通过结合后焦平面（BFP）显微镜的偏振成像和斯托克斯参数分析，我们展示了我们的结构作为微型片上偏振转换器的功能。我们的结果表明，这种纳米结构能够实现复杂的偏振转换，包括将线偏振转换为圆偏振以及反之亦然。发现偏振转换效率取决于圆形光栅的周期，并且在傅里叶空间的中心区域尤为明显。此外，强烈的不对称散射导致在各种入射偏振态下斯托克斯参数出现独特的图案。这项工作为纳米尺度下光偏振的表面等离激元操纵提供了见解，在微型片上偏振转换器、偏振控制发射器和先进传感技术方面具有潜在应用。
