Abstract Access to surface plasmon polaritons (SPPs) with directional control excited by electrical means is important for applications in (on-chip) nano-optoelectronic devices and to circumvent limitations inherent to approaches where SPPs are excited by optical means (e.g., diffraction limit). This paper describes directional excitation of surface plasmon polaritons propagating along a plasmonic strip waveguide integrated with an aperiodic groove array electrically driven by an Al–Al2O3–Au tunnel junction. The aperiodic groove array consists of six grooves and is optimized to specifically reflect the SPPs by 180° in the desired direction (+x or −x) along the plasmonic strip waveguide. We used constrained nonlinear optimization of the groove array based on the sequential quadratic programming algorithms coupled with finite-difference time-domain (FDTD) simulations to achieve the optimal structures. Leakage radiation microscopy (Fourier and real plane imaging) shows that the propagation direction of selectively only one SPP mode (propagating along the metal–substrate interface) is controlled. In our experiments, we achieved a directionality (i.e., +x/−x ratio) of close to 8, and all of our experimental findings are supported by detailed theoretical simulations.

中文翻译：

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通过电驱动非周期性凹槽阵列反射器定向发射表面等离子体激元

摘要 获得具有由电方式激发的方向控制的表面等离子体激元 (SPP) 对于（片上）纳米光电器件中的应用和规避 SPP 由光学方式激发的方法固有的限制（例如，衍射极限）很重要。 . 本文描述了沿等离子体条形波导传播的表面等离子体极化激元的定向激发，该等离子体条形波导与由 Al-Al2O3-Au 隧道结电驱动的非周期性凹槽阵列集成。非周期性凹槽阵列由六个凹槽组成，并经过优化以沿等离子体条形波导在所需方向（+x 或 -x）上将 SPP 反射 180°。我们使用基于顺序二次规划算法结合有限差分时域 (FDTD) 模拟的凹槽阵列的约束非线性优化来实现最佳结构。泄漏辐射显微镜（傅立叶和实平面成像）显示，选择性地仅控制一种 SPP 模式（沿金属 - 基板界面传播）的传播方向。在我们的实验中，我们实现了接近 8 的方向性（即 +x/−x 比率），并且我们所有的实验结果都得到了详细的理论模拟的支持。