Department of Physics, Indian Institute of Technology Kanpur, Kanpur, India.
Opt Lett. 2011 Sep 15;36(18):3705-7. doi: 10.1364/OL.36.003705.
Surface enhanced Raman scattering has been investigated from rhodamine 6G molecules embedded in polymethyl methacrylate (R6G+PMMA) and coated on one-dimensional and two-dimensional gold-dielectric gratings fabricated by laser interference lithographically. The Raman signals from these plasmonic templates are 200 to 400 times larger than the signal from R6G+PMMA coated on plain gold films. The enhancement of the Raman signal varies almost periodically with the period of the grating. Finite-difference time-domain simulations show that large electromagnetic near fields occur at the metallic edges due to the resonant excitation of localized surface plasmon of the gold patches by the pump laser. These give rise to large enhancements of the Raman signal. The dependence on period is due to the combined effects of the localized surface plasmon and the periodic grating that couples the pump laser to the surface plasmon polariton.
表面增强拉曼散射已从嵌入聚甲基丙烯酸甲酯的罗丹明 6G 分子（R6G+PMMA）中进行了研究，并涂覆在通过激光干涉光刻制造的一维和二维金-介电光栅上。这些等离子体模板的拉曼信号比涂覆在普通金膜上的 R6G+PMMA 的信号大 200 到 400 倍。拉曼信号的增强几乎随光栅的周期呈周期性变化。有限差分时域模拟表明，由于泵浦激光对金片的局域表面等离激元的共振激发，在金属边缘会产生大的电磁场近场。这导致拉曼信号的大幅增强。对周期的依赖性是由于局域表面等离激元和周期性光栅的组合效应所致，该效应将泵浦激光耦合到表面等离激元极化激元上。
