Coupling Efficiency of Surface Plasmon Polaritons: Far- and Near-Field Analyses

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• 作者：Tahir Iqbal
• 关键词：Surface plasmon polaritons (SPPs) ; Coupling efficiency ; Scanning near field optical measurements ; Far ; field and near ; field modeling
• 刊名：Plasmonics
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：12
• 期：1
• 页码：215-221
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Biotechnology; Nanotechnology; Biophysics and Biological Physics; Biochemistry, general;
• 出版者：Springer US
• ISSN：1557-1963
• 卷排序：12

文摘

The excitation of surface plasmon polaritons (SPPs) through one-dimentional (1D) metallic (Au) grating on higher refractive index -GaP substrate is investigated. Such grating devices find potential applications in real world, only if the coupling efficiency (η) of a free-space transverse-magnetic plane-wave into a SPPs mode is maximum. A simple and robust technique is used to estimate the η, by simply measuring the transmission through the grating while varying slit width (a) but period (Λ) and the thickness (t) remain fixed. When the wave vector (k₀) of the incident light is matched to that of SPP, highest η is achieved. It is found that Λ/3 < a < Λ/2 yields a maximum η where the intermediate scattering couples more incident energy to SPPs. These gratings are designed in such a way that they support only the fundamental plasmonic mode yielding higher η. Scanning near-field optical measurements also confirm and corroborate the observations of far-field and near-field modeling (COMSOL multiphysics) results.