Enhanced Transmission through Periodic Arrays of Subwavelength Holes: The Role of Localized Waveguide Resonances

Department of Microelectronics and Applied Physics (MAP), KTH Royal Institute of Technology, Tukholma, Stockholm, Sweden
Physical Review Letters (Impact Factor: 7.51). 07/2006; 96(23):233901. DOI: 10.1103/PhysRevLett.96.233901
Source: PubMed


By using the rigid full-vectorial three-dimensional finite-difference time-domain method, we show that the enhanced transmission through a metallic film with a periodic array of subwavelength holes results from two different resonances: (i) localized waveguide resonances where each air hole can be considered as a section of metallic waveguide with both ends open to free space, forming a low-quality-factor resonator, and (ii) well-recognized surface plasmon resonances due to the periodicity. These two different resonances can be characterized from electromagnetic band structures in the structured metal film. In addition, we show that the shape effect in the enhanced transmission through the Au film with subwavelength holes is attributed to the localized waveguide resonance.

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    • "The resonance mechanisms behind EOT have been proved theoretically and experimentally, which mainly correspond to the SPP and cavity mode (CM) [11] [12] [13] [14]. There are many applications by using SPP [15] [16] [17] and CM [18] [19], but here we consider to combine the SPP and CM for plasmonic sensing. "
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    ABSTRACT: A novel spatial and spectral selective plasmonic sensing based on the metal nanoslit arrays has been proposed and investigated theoretically, which shows a high performance in the multiplexing biomolecular detections. By properly tuning the geometric parameters of metal nanoslit arrays, the enhanced optical fields at different regions can be obtained selectively due to the excitation of SPP, cavity mode (CM), and their coupling effects. Simulation results show that the resonances of the metal nanoslit arrays at different spatial locations and different wavelengths can be achieved simultaneously. A relative bigger red-shift of 57 nm can be realized when a layer of biomolecular film is adsorbing at the slit walls, and the corresponding total intensity difference will be enhanced near 10 times compared to that at the top surface. In addition, when a BSA protein monolayer is adsorbing at slit walls with different slit widths, the corresponding wavelength shifts can reach to more than 80 nm by modulating the widths of the slit. The simulated results demonstrate that our designed metal nanoslit arrays can serve as a portable, low-cost biosensing with a high spatial and spectral selective performance.
    Full-text · Article · Jan 2016 · Optics Communications
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    • "The introduction of voids into a thin film significantly alters the characteristics of the medium, leading to exotic and interesting physical properties. In fact, such voids can lead to quantum effects in the conductivity [1] [2], enhanced optical transmission [3], artificial vortex pinning sites in superconductors [4] and magnonic crystals [5] [6], facilitating research and technological applications. Regarding magnetic materials, the inclusion of these artificial defects becomes an easy way to engineer their properties at micrometer and nanometer scales [7] [8]. "
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    ABSTRACT: In this work, we use anodic aluminum oxide (AAO) templates to build NiFe magnetic nanohole arrays. We perform a thorough study of their magnetic, electrical and magneto-transport properties (including the resistance R(T), and magnetoresistance MR(T)), enabling us to infer the nanohole film morphology, and the evolution from granular to continuous film with increasing thickness. In fact, different physical behaviors were observed to occur in the thickness range of the study (2 nm < t < 100 nm). For t < 10 nm, an insulator-to-metallic crossover was visible in R(T), pointing to a granular film morphology, and thus being consistent with the presence of electron tunneling mechanisms in the magnetoresistance. Then, for 10 nm < t < 50 nm a metallic R(T) allied with a larger anisotropic magnetoresistance suggests the onset of morphological percolation of the granular film. Finally, for t > 50 nm, a metallic R(T) and only anisotropic magnetoresistance behavior were obtained, characteristic of a continuous thin film. Therefore, by combining simple low-cost bottom-up (templates) and top-down (sputtering deposition) techniques, we are able to obtain customized magnetic nanostructures with well-controlled physical properties, showing nanohole diameters smaller than 35 nm. (Some figures may appear in colour only in the online journal)
    Full-text · Article · Feb 2013 · Journal of Physics Condensed Matter
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    • "Very recently, an array of holes with very acute angles was found to exhibit a strong EOT effect caused by the LSP [27], an array of three-dimensional holes was also found that it has strong EOT effect induced by the LSP [28]. The waveguide mode across each hole can also play an important role in the extraordinary transmission through Fabry–Perot resonance [14, 29]. Until now, there have been no reports about the extraordinary transmission in a non-planar asymmetric structure. "
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    ABSTRACT: We developed a method to fabricate a periodic array of three-dimensional crescent-like holes (3DCLH) via an inverted hemispherical colloidal lithography. It is found that there exists an extraordinary optical transmission in this non-planar perforated periodic array of 3DCLH when the electric field of the incident light is perpendicular to the cross-line of the crescent-like hole. This extraordinary optical peak is insensitive with the incident angles and sensitive with the angle between the electric field of the incident light to the cross-line of the 3DCLH. Numerical simulation based on finite-difference time-domain method reveals that this peak is caused by an asymmetric localized surface plasmon resonance. This structure might be useful for the optical sensing and optical-integrated circuits.
    Full-text · Article · Jun 2012 · Plasmonics
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