基于增益媒质的亚波长纳米阵列超传输特性研究

Extraordinary Optical Transmission Coupled to A Gain Medium Based on The Subwavelength Nanostructure

增益媒质因其优良的放大特性和广阔的应用前景吸引了国内外学者的广泛关注,然而,激发增益媒质补偿欧姆损耗需要较强的外部能量,极大地限制了增益媒质的发展前景。本文使用辅助位微分方程的时域有限差分方法研究了麦克斯韦方程与半经典的电子速率方程相耦合的自洽仿真过程,并基于四能级原子系统描述的增益媒质和异常光传输现象间的耦合机制,提出了一种新颖的含亚波长周期裂缝的增益/金属/增益纳米阵列结构。研究结果表明,本文提出的纳米结构可以使用较低外部能量实现完全补偿欧姆损耗的目的。该结果对深入了解纳米结构和增益媒质之间的相互作用有着重要的意义。

As a focus on the study of metamaterials, the gain medium attracts a wide range of attention due to its excellent amplification characteristics. However, high external energy is needed to excite the gain material to compensate loss or create laser, which greatly limits the practical application of the gain materials. We investigate a computational scheme allowing for a self-consistent treatment of periodic arrays of subwavelength apertures coupled to a gain material incorporated into the nanostructure. Taking advantage of the amplification of extraordinary optical transmission(EOT) phenomena, the resonant electric-field intensity is enhanced associated with the effect of surface plasmon polariton(SPP). We present a simulation framework allowing for EOT coupled to gain media, which enables complete Ohmic loss compensation by using a moderate pump intensity level. The active gain media is represented with four-level atomic system by solving the semiclassical electronic rate equations. Finite-difference time-domain(FDTD) method incorporated with auxiliary differential equation is used to simulate electromagnetic field. Our results can be used as instruction for the realistic experiments, and provide a deep insight into the interaction between nanostructure and gain materials.