Zar Tchiya, Krause Alon, Shavit Omer, Aharon Hannah, Ron Racheli, Oheim Martin, Salomon Adi
Department of Chemistry, BINA Nano Center for advanced materials, Bar-Ilan University, Ramat-Gan, Israel.
Université Paris Cité, CNRS, Saints Pères Paris Institute for the Neurosciences, F-75006 Paris, France.
Phys Chem Chem Phys. 2023 Jul 19;25(28):18915-18925. doi: 10.1039/d3cp01678a.
Metamaterials and plasmonic structures made from aluminum (Al) have attracted significant interest due to their low cost, long-term stability, and the relative abundance of aluminum compared to the rare metals. Also, aluminum displays distinct dielectric properties allowing for the excitation of surface plasmons in the ultraviolet region with minimal non-radiative losses. Despite these clear advantages, most of the research has been focused on either gold or silver, probably due to difficulties in forming smooth thin films of aluminum. In the present work, we detect and characterize second harmonic generation (SHG) in the optical regime, emanating from triangular hole arrays milled into thin aluminum films in reflection mode, at normal incidence. We report intense nonlinear responses, year-long stability, and overall superior performances with respect to gold. The robustness of the Al structures and high reproducibility of the measured SHG responses allowed us to investigate changes in the directional emission upon tiny modifications in the structure's symmetry. We also demonstrate large-field instantaneous SHG imaging over areas containing several hole arrays using a recent, non-linear single-spinning disk microscope. Such high spatio-temporal resolution imaging has important applications, , when studying chemical transformations occurring at electrode surfaces during charging and discharging cycles, as well as ageing.
由铝（Al）制成的超材料和等离子体结构因其低成本、长期稳定性以及与稀有金属相比铝的相对丰富性而引起了极大的关注。此外，铝具有独特的介电特性，能够在紫外区域激发表面等离子体，且非辐射损耗最小。尽管有这些明显的优势，但大多数研究都集中在金或银上，这可能是由于难以形成光滑的铝薄膜。在本工作中，我们检测并表征了光学波段中的二次谐波产生（SHG），它源于在反射模式下垂直入射时铣削到薄铝膜中的三角形孔阵列。我们报告了强烈的非线性响应、长达一年的稳定性以及相对于金而言总体更优异的性能。铝结构的稳健性以及所测量的SHG响应的高再现性使我们能够研究结构对称性发生微小变化时方向发射的变化。我们还使用一种新型的非线性单旋转盘显微镜展示了在包含多个孔阵列的区域上的大场瞬态SHG成像。这种高时空分辨率成像在研究充电和放电循环以及老化过程中电极表面发生的化学转变时具有重要应用。
