Yu Yue, Si Jiangnan, Ning Yaying, Sun Minghai, Deng Xiaoxu
Opt Lett. 2017 Jan 15;42(2):187-190. doi: 10.1364/OL.42.000187.
A plasmonic wavelength splitter based on a sub-wavelength metal-insulator-metal (MIM) periodic rectangle wrinkle waveguide with a graded grating coupler is theoretically analyzed and experimentally demonstrated. The surface plasmon polaritons (SPPs), excited in the metal grating with wavelength selection, are deflected by the graded difference according to the aplanatic parametric principle. The wave vector of the deflected SPPs meets the phase-matching condition and couples into the periodic rectangle wrinkle waveguide with a plasmonic bandgap. The characteristic of the plasmonic wavelength splitter is simulated by finite difference time domain (FDTD) simulation, which agrees well with the theoretical analysis. By electron beam lithography and ion beam etching process, the plasmonic wavelength splitter was fabricated. The SPPs excited by incident 650 and 832 nm were successfully split and guided to opposite directions of the MIM waveguide with extinction ratios of 27.5 dB and 32.7 dB, respectively, which was observed under an optical microscope using a CCD camera. The proposed wavelength splitter is simple fabricated and has a large coupling aperture by utilizing the graded grating coupler.
基于带有渐变光栅耦合器的亚波长金属-绝缘体-金属（MIM）周期性矩形褶皱波导的表面等离子体激元波长分离器，在理论上进行了分析并通过实验进行了演示。在具有波长选择功能的金属光栅中激发的表面等离子体激元极化激元（SPP），根据消球差参数原理，因渐变差异而发生偏转。偏转后的SPP的波矢满足相位匹配条件，并耦合到具有表面等离子体带隙的周期性矩形褶皱波导中。利用时域有限差分（FDTD）模拟对表面等离子体激元波长分离器的特性进行了模拟，模拟结果与理论分析结果吻合良好。通过电子束光刻和离子束蚀刻工艺制备了表面等离子体激元波长分离器。在光学显微镜下使用电荷耦合器件（CCD）相机观察到，由650和832 nm入射光激发的SPP成功地被分离，并分别以27.5 dB和32.7 dB的消光比被引导到MIM波导的相反方向。所提出的波长分离器制作简单，并且通过利用渐变光栅耦合器具有较大的耦合孔径。
