Gao H, McMahon J M, Lee M H, Henzie J, Gray S K, Schatz G C, Odom T W
Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
Opt Express. 2009 Feb 16;17(4):2334-40. doi: 10.1364/oe.17.002334.
Surface plasmon polaritons (SPPs) and Rayleigh anomalies (RAs) are two characteristic phenomena exhibited by periodic grating structures made of plasmonic materials. For Au subwavelength hole arrays, SPPs and RAs from opposite sides of the film can interact under certain conditions to produce highly intense, narrow spectral features called RA-SPP resonances. This paper reports how RA-SPP effects can be achieved in subwavelength hole arrays of Pd, a weak plasmonic material. Well-defined resonances are observed in measured and simulated optical transmission spectra with RASPP peaks as narrow as 45 nm (FWHM). Dispersion diagrams compiled from angle-resolved spectra show that RA-SPP resonances in Pd hole arrays shift in wavelength but do not decrease significantly in amplitude as the excitation angle is increased, in contrast with RA-SPP peaks in Au hole arrays. The apparent generality of the RA-SPP effect enables a novel route to optimize resonances in non-traditional plasmonic media.
表面等离激元极化激元（SPPs）和瑞利异常（RAs）是由等离子体材料制成的周期性光栅结构所表现出的两种特征现象。对于金亚波长孔阵列，来自薄膜两侧的SPPs和RAs在一定条件下可以相互作用，产生称为RA-SPP共振的高强度、窄光谱特征。本文报道了如何在弱等离子体材料钯的亚波长孔阵列中实现RA-SPP效应。在测量和模拟的光学透射光谱中观察到了明确的共振，RA-SPP峰窄至45纳米（半高宽）。从角分辨光谱编制的色散图表明，与金孔阵列中的RA-SPP峰相比，钯孔阵列中的RA-SPP共振波长发生偏移，但随着激发角的增加，幅度不会显著降低。RA-SPP效应的明显普遍性为优化非传统等离子体介质中的共振提供了一条新途径。
