设计了一种带圆角的金属脊和低折射率空气间隙的新型混合表面等离子体波导结构。基于有限元法建立数学模型, 在工作波长为489 nm的可见光波段研究了该波导的电场分布、归一化模式面积、传输距离、品质因子和珀塞尔因子随金属脊曲率半径的变化情况。结果表明, 调整结构参数可使波导实现超深亚波长的光场限制, 同时获得较大的SPPs辐射增强倍数。在最优几何参数(纳米线半径为95 nm, 金属脊曲率半径为20 nm)下, 波导有效模式面积为0.0037λ2, 品质因子为268, 珀塞尔因子为65, 增益阈值为 0.2768 μm-1, 其表征激光增强值为69800。该激光器谐振腔具有超强的局域能力和激光增强能力, 可以实现超深亚波长的低阈值激射。

A novel hybrid surface plasmon waveguide structure with rounded metal ridge and low refractive index air gaps is designed. The changes of electric field distribution, normalized mode area, transmission distance, quality factor and Purcell factor with radius of metal ridge curvature are studied at operating wavelength of 489 nm. The results show that the waveguide can achieve a larger radiation enhancement factor while ultra-deep subwavelength optical field can be limited by adjustment of structure parameters. The optimal geometric parameters are as follows: nanowire radius and curvature radius are 95 nm and 20 nm, respectively. Under the optimal parameters, effective mode area is 0.0037λ2, quality factor is 268, Purcell factor is 65 and gain threshold is 0.2768 μm-1. The value of the laser enhancement is calculated as 69800. Resonant cavity of the laser has superior local ability and laser enhancement ability, and can realize low threshold excitation of ultra-deep subwavelength.