Inefficient and wide‐angle emission as well as low emission rate of optical nanoemitters (such as quantum dots) have been strongly limiting their practical applications in next‐generation nanophotonic devices, such as nanoscale light‐emitting diodes (LEDs) and on‐chip single photon sources. Optical nanoantennas provide a promising way to deal with these challenges. Yet, there has been no solution that can overcome these drawbacks simultaneously on a single device. Here, a hybrid plasmonic nanoantenna consisting of a silver nanocube positioned at the center of a gold concentric‐ring structure is proposed, which can simultaneously enhance the emission directionality and decay rate of quantum dots embedded in the nanogap beneath the nanocube while maintaining high quantum efficiency. Coupling quantum dots to this nanoantenna can result in 60% of the emitted photons collected by the first lens with a numerical aperture (NA) of 0.5 and 21% for a NA of 0.12. The total emission intensity and decay rate are enhanced by 121‐fold and 424‐fold, respectively, compared with quantum dots on a glass substrate. A high quantum efficiency above 50% is obtained in simulation. This novel platform can be applied to enhance various types of optical nanoemitters and to develop high‐speed directional nano‐LEDs and single photon sources.

中文翻译：

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混合等离子纳米天线可实现单向，超快和明亮的自发发射源

光学纳米发射器（例如量子点）的低效率和广角发射以及低发射率已经严重限制了它们在下一代纳米光子器件（例如纳米级发光二极管（LED）和片上单芯片）中的实际应用。光子源。光学纳米天线提供了一种有希望的方式来应对这些挑战。但是，还没有一种解决方案可以在单个设备上同时克服这些缺点。在这里，提出了一种混合等离子纳米天线，它由位于金同心环结构中心的银纳米立方体组成，可以同时提高嵌入在纳米立方体下方纳米间隙中的量子点的发射方向性和衰减率，同时保持高量子效率。将量子点耦合到该纳米天线可导致第一透镜收集的发射光子中有60％的数值孔径（NA）为0.5，对于NA为0.12的数值孔径为21％。与玻璃基板上的量子点相比，总发射强度和衰减率分别提高了121倍和424倍。在仿真中获得了高于50％的高量子效率。这个新颖的平台可用于增强各种类型的光学纳米发射器，并开发高速定向纳米LED和单光子源。