Verhagen Ewold, Kuipers L, Polman Albert
Center for Nanophotonics, FOM-Institute for Atomic and Molecular Physics (AMOLF), Science Park 113, 1098 XG Amsterdam, The Netherlands.
Opt Express. 2009 Aug 17;17(17):14586-98. doi: 10.1364/oe.17.014586.
Upconversion luminescence from erbium ions placed in the near field of subwavelength aperture arrays is used to investigate field enhancement of incident near-infrared light in such nanostructures. We study field enhancement due to the excitation of both propagating and localized surface plasmon resonances in arrays of square and annular apertures in a Au film. The conversion of 1480 nm excitation light to 980 nm emission is shown to be enhanced up to a factor 450 through a subwavelength hole array. The effects of array periodicity and aperture size are investigated. It is shown that a Fano model can describe both far-field transmission and near-field intensity. The upconversion enhancement reveals the wavelength and linewidth of the surface plasmon modes that are responsible for extraordinary transmission in such arrays. Angle-dependent measurements on annular aperture arrays prove that the field enhancement due to localized resonances is independent of the incident angle. These experiments provide insight in the mechanisms responsible for extraordinary transmission and are important for applications that aim to exploit near-field enhancement in nanostructured metal films.
将铒离子置于亚波长孔径阵列的近场中产生的上转换发光，被用于研究此类纳米结构中入射近红外光的场增强情况。我们研究了金膜中方形和环形孔径阵列中传播表面等离子体共振和局域表面等离子体共振激发所导致的场增强。通过亚波长孔阵列，1480 nm激发光到980 nm发射光的转换增强了450倍。研究了阵列周期性和孔径大小的影响。结果表明，法诺模型可以描述远场透射和近场强度。上转换增强揭示了对此类阵列中异常透射起作用的表面等离子体模式的波长和线宽。对环形孔径阵列的角度相关测量证明，局域共振导致的场增强与入射角无关。这些实验深入了解了导致异常透射的机制，对于旨在利用纳米结构金属膜中近场增强的应用具有重要意义。
