Hamidi Jafar, Zavvari Mahdi
Appl Opt. 2018 Dec 20;57(36):10505-10509. doi: 10.1364/AO.57.010505.
Recently, quantum confined structures have been widely studied for their nonlinear properties and applications in harmonic generation. However, because of lower orders of susceptibility, the generated harmonic power is low. In this paper, we present coupling of metamaterial resonance to intersubband transitions of quantum dots (QDs) for enhanced second-harmonic generation efficiency. To do so, first the QDs are designed so as to exhibit three electronic energy levels with identical energy spacing. The values of energy levels and the wave functions are calculated by solving the Schrödinger equation using modified effective mass approximation. The second-order nonlinear susceptibility of QD layers is then calculated, and the results are used in finite-difference time domain (FDTD) simulation of structure. Metamaterial structure is also designed to resonate in response to the frequency of QDs. The results show that for a pump input with 24 THz fundamental frequency, a harmonic with the 48 THz frequency appears in the output, with conversion efficiency of about 5×10.
近年来，量子限域结构因其非线性特性以及在谐波产生方面的应用而受到广泛研究。然而，由于较低的极化率阶数，所产生的谐波功率较低。在本文中，我们提出将超材料共振与量子点（QD）的子带间跃迁相耦合，以提高二次谐波产生效率。为此，首先设计量子点，使其呈现出具有相同能级间距的三个电子能级。通过使用修正的有效质量近似求解薛定谔方程来计算能级值和波函数。然后计算量子点层的二阶非线性极化率，并将结果用于结构的时域有限差分（FDTD）模拟。超材料结构也被设计为响应量子点的频率而发生共振。结果表明，对于具有24太赫兹基频的泵浦输入，输出中出现了频率为48太赫兹的谐波，转换效率约为5×10。
