It is well known that the intersubband radiation of InAs/GaAs quantum dots (QDs) falls in the terahertz/far-infrared spectral region. If these so-called atom-like systems are placed in the vicinity of graphene, their radiation can be coupled with plasmonic modes of graphene. As the graphene plasmons tightly concentrate the electromagnetic waves in the small zones, beyond the diffraction limit, the optical properties of QDs can then be enhanced by the so-called Purcell effect if frequency tuning and mode overlapping are well performed. Owing to this idea, in this work, we report on the enhancement of linear and third-order optical susceptibilities of truncated pyramidal-shaped InAs/GaAs QDs with use of graphene plasmonics. Graphene flakes in various configurations were located inside the QDs, and their transition dipole moments (TDMs) were calculated. Our results show 120-fold enhancement in TDM with optimization on the flakes’ and QDs’ geometries. Consequently, the linear and nonlinear optical susceptibilities of QDs are enhanced noticeably. Precisely, the linear and third-order susceptibilities of QDs with base length of 25 nm and height of 3 nm were enhanced enormously up to ${1.18} \times {{10}^5}$ and ${1.4} \times {{10}^{10}}$ times, respectively. This passive method is promising for enhancing the performance of QD-based optoelectronic devices such as lasers, LEDs, sensors, and so on.

中文翻译：

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石墨烯等离子体耦合与截锥形 InAs/GaAs 量子点的子带间辐射

众所周知，InAs/GaAs 量子点 (QD) 的子带间辐射落在太赫兹/远红外光谱区。如果这些所谓的类原子系统被放置在石墨烯附近，它们的辐射可以与石墨烯的等离子体模式耦合。由于石墨烯等离子体将电磁波紧密地集中在小区域中，超出了衍射极限，如果频率调谐和模式重叠能够很好地执行，则可以通过所谓的珀塞尔效应增强 QD 的光学特性。由于这个想法，在这项工作中，我们报告了使用石墨烯等离子体增强截断金字塔形 InAs/GaAs QD 的线性和三阶光学磁化率。各种配置的石墨烯薄片位于 QD 内部，并计算了它们的跃迁偶极矩（TDM）。我们的结果显示 TDM 增强了 120 倍，并优化了薄片和 QD 的几何形状。因此，量子点的线性和非线性光学磁化率显着增强。准确地说，基长为 25 nm 和高度为 3 nm 的 QD 的线性和三阶磁化率显着提高至${1.18} \times {{10}^5}$和${1.4} \times {{10}^{10}}$次，分别。这种被动方法有望提高基于 QD 的光电器件（如激光器、LED、传感器等）的性能。