基于混合表面等离子体波导的纳米激光器的研究

设计了一种带有金属脊和低折射率介质夹层的新型混合表面等离子体波导结构,利用有限元法对该结构进行了数值仿真。COMSOL Multiphysics软件是一款基于有限元法模拟真实物理现象的仿真软件。在COMSOL Multiphysics软件平台上,构建该结构的三维模型,使用模态分析和频域分析模块,研究了其电场分布、归一化模式面积、传输长度、增益阈值、品质因数。结果表明：在工作波长为370 nm时,所设计波导的光场约束可达到较好的深亚波长水平,同时保持大的传输长度。提出的带有金属脊结构与平坦金属层结构相比,波导特性更好。将该结构应用于纳米激光器,由基模和纵模反映出,激光器内光场分布稳定且集中在极小的面积内。在波导特性良好的情况下,该激光器可保持较低的增益阈值和较高的谐振腔品质因数。综合考虑,选取最优尺寸为ｒ＝80 nm, d＝45 nm,此时有效模式面积为0.005 1λ2,传输长度为1 668 nm,增益阈值为1.46×10-6 m-1, 品质因子74.5。最后,在最优尺寸下,通过仿真得到了该结构的发射光谱,其发射波长为360 nm,输出电能比输入电能增强了3 100倍。该结构为小型化和集成化的纳米设备提供了技术支持,在生物医学和光通信等领域有广泛的应用前景。

A Hybrid Plasmonic Waveguide for Nanolaser Applications

In this paper, a novel hybrid plasmonic waveguide with a metal ridge and a dielectric layer of low refractive index was demonstrated. We numerically simulated the waveguide by using finite-element method. The COMSOL Multiphysics Software is a superior numerical simulation software to simulate the real physical phenomena based on finite element method. On the basic of the COMSOL Multiphysics Software, a three-dimensional model was built. Using the modal analysis module and the frequency domain analysis module, we analyzed the normalized mode scaling factor, distance, lasing threshold and quality factor. The results indicated that the waveguide structure can reach good deep-subwavelength mode confinement while maintaining long distance at the 370 nm working wavelength. Compared to the previously reported structure with a metal plate, it has better waveguide performance. When this structure applied to nanolasers, the electric field distribution in nanolasers is stable and concentrated on a tiny area. In the case of good waveguide characteristic, the nanolasers can keep low gain threshold and high quality factor of the resonant cavity at the 370 nm working wavelength. By comprehensive consideration, the optimal size can be choosed as ｒ＝80 nm, d＝45 nm. In this case, the effective mode area was , the distance was 1 668 nm, the lasing threshold was 1.68, and the quality factor was 74.5. Finally, the emission spectrum was obtained by simulation at the optimal size. The emission wavelength was 360 nm, and the output power was increased 3 100 times than the input power. This structure affords technical support to miniaturization and integration of lasers which have broad application prospects in the field of the biomedical and optical communications.