激光与电磁场作用的自洽多物理仿真算法及其应用研究

The electromagnetic properties of existing materials in the nature limit the further development of the electromagnetic device performance. The new artificial electromagnetic materials(metamaterials) can greatly expand the electromagnetic device design and development of space, to improve the device performance, to achieve breakthrough new electromagnetic device. .Most of these artificial materials,designed to have specially tailored properties not to be found in nature, exploit plasmonic effects and are therefore composed of metallic building blocks. Unfortunately, metal nanoparticles suffer from intrinsic losses due to absorption, which are especially severe in the optical wavelength regime..Conclusively, it is currently one of the most important goals of the metamaterial and plasmonics community to compensate or at least reduce these intrinsic losses in the metal structures. The project intends to use the laser to compensate the loss of and study the specific mechanism.. We will study theoretically the self-consistent process of the lasing and electromagnetic field theory and further provide verification for the real experimental results. Specifically, the following aspects of the work are to be carried out:.(1)Using the four level rate equations to describe the process of particle evolution, and constructing coupled equations to describe the interaction with the classical electromagnetic field;.(2)Seeking the high-precision model to describe the electromagnetic dispersion characteristics of the metal in optic frequency, such as the Drude,the Lorentz and Drude plus Lorentz model, which can be applied in time domain simulation using FDTD algorithm;.(3)Applying the parallel FDTD algorithm to numerical simulate the corresponding multiphysics system built by the self-consistent multiphysics model, and the experimental results will be compared to verify the built model; the physical mechanism of the loss of metamaterials will also be explored.

目前自然界中现有材料的电磁性质限制了电磁器件性能的进一步发展，新型人工电磁材料的研究可以大大拓宽电磁器件设计和开发空间、提高器件性能，实现具有突破性的新型电磁器件。遗憾的是绝大多数人工电磁材料是由金属构成，因此在光波及近红外波段如何有效地降低甚至补偿金属损耗越来越引起国内外学者的关注。本项目拟从理论上探讨利用激光以补偿损耗的具体机理，通过激光与电磁场自洽场过程的实验模拟验证所提理论。具体来说，拟开展如下几方面的工作：.（1）利用描述粒子演化过程的四能级速率方程，构造其与经典电磁场相互作用的耦合方程；.（2）寻求适宜时域模拟的高精度模型以描述光波段金属的电磁色散特性，如Drude、Lorentz及Drude与Lorentz叠加等模型；.（3）利用并行时域有限差分算法对所建的多物理系统进行多物理自洽过程的模拟，并与实验结果进行对比验证所建算法；探讨其在典型新型人工电磁材料损耗弥补中的物理机理。

围绕项目，针对项目研究内容，按照研究计划做了如下几方面的工作：.1.建立了处理激光系统及电磁场方程自洽模型的统一处理方法。具体来说就是建立了描述激光场的半经典四能级速率方程，利用FDTD对该方程进行离散求解；对时域电磁场方程依据经典的Yee网格离散，借助于FDTD进行数值求解。最终将构建的算法应用于四能级激光系统电磁仿真。.2.建立了激光场与电磁场相互耦合的多物理场模型，利用FDTD方法实现了其并行化程序。研究了典型含增益人工电磁超材料在泵浦-探测试验中不同的物理机制，为有源电磁超材料的应用提供了技术支持。.3.利用辛积分技术和高阶交错差分技术建立了双色散电磁超材料的仿真与含时薛定谔方程的高阶辛算法（SFDTD(4,4)），在时间上采用四阶辛积分格式离散，空间上采用四阶精度的差分格式离散；探讨了SFDTD(4,4)法的稳定性，获得了含时薛定谔方程的一维以及多维的稳定性条件，并且得到了在含势能情况下该稳定性条件的具体表达式；借助复坐标沿伸概念，实现了SFDTD(4,4)法在量子器件模拟中的完全匹配层吸收边界条件。..项目获得资助以来，已发表学术论文45篇，其中SCI收录16篇，EI收录19篇。受邀撰.写中文专著一部，获安徽省科技进步二等奖一项，培养博士3名，硕士7名。