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ABSTRACT: A semianalytical Fabry-Perot model is presented to investigate the electromagnetic enhancement by double grooves in gold substrate. The influence of hybrid wave (HW) propagating along the metal surface on field enhancement is explored systematically with a HW model. Simulation results imply that the hybrid generated by one groove can affect the mode fields in the other groove after propagating along the metallic surface. Giant electromagnetic field intensity at resonance condition is found for the groove distance of 0.6λ with the contribution of surface waves, which is nearly independent of the incidence wavelength and groove width.
Optics Letters 12/2012; 37(23):4898-900. · 3.40 Impact Factor
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ABSTRACT: The electromagnetic properties of subwavelength metallic surfaces are due to
two kinds of elementary distinct waves, the famous surface plasmon polariton
and the quasi-cylindrical wave, which are both scattered by the subwavelength
indentations as they propagate on the metal. The ab-initio microscopic
description of the electromagnetic properties starting from the sole knowledge
of the elementary waves launched in between the indentation has a long history
in grating theories. We review the evolution of the ideas and the fundamental
principles that govern these waves and their impacts. For the sake of
illustration, the emblematic case of a metal surface perforated by a
subwavelength-hole array, which exhibits remarkable transmission properties, is
taken to illustrate our purpose.
07/2012;
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ABSTRACT: We present comprehensive investigations of the electromagnetic enhancement by a periodic array of rectangular nanogrooves in a metallic substrate. The impacts of array parameters and of illumination conditions on the enhanced electric-field intensity are explored using fully vectorial methods. The calculations are performed mainly for gold and for the visible and infrared wavelengths. The fully vectorial results are reproduced and explained by a simple Fabry-Perot model. Compared with the case of a single groove, the electric-field enhancement of the groove array is found to be much higher by almost 1 order of magnitude, which is shown to be related to the excitation of surface plasmon polaritons with the aid of the model. Practical considerations of a finite groove number and of a finite groove length are also provided.
Journal of the Optical Society of America A 05/2011; 28(5):879-86. · 1.56 Impact Factor
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ABSTRACT: As shown in a recent letter [Nature 452, 728 (2008)] with a microscopic model, the phenomenon of the extraordinary optical transmission (EOT) is intrinsically due to two distinct surface waves: the surface plasmon polariton and the quasi-cylindrical wave (quasi-CW) that efficiently funnel light into the hole aperture at resonance. Here we present a comprehensive microscopic model of the EOT that takes into account the two surface waves. The model preserves the desirable physical insight of the previous approach, but since it additionally takes into account the quasi-CWs, it provides highly accurate predictions over a much broader spectral range, from visible to microwave radiation. The net outcome is a complete understanding of many aspects of the EOT and especially of the role of the metal conductivity that has largely puzzled the initial interpretations. We believe that the main conclusions of the present analysis may be applied to many Wood-type surface resonances on metallic surfaces.
Journal of the Optical Society of America A 12/2010; 27(12):2542-50. · 1.56 Impact Factor
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ABSTRACT: We propose systematic investigations of the electromagnetic enhancement by a single nano-groove in gold substrate. The impacts of the groove parameters and of the illumination conditions on the enhanced intensity are explored using a fully vectorial numerical method. The obtained data can be well predicted and explained by a simple Fabry-Perot model. By virtue of the semi-analytical model, we identify two main factors that enable giant electric-field enhancement in very narrow grooves: the Fabry-Perot resonance and the large wave impedance of the fundamental mode in the groove.
Journal of the Optical Society of America A 07/2010; 27(7):1555-60. · 1.56 Impact Factor
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ABSTRACT: The electromagnetic interaction between nano-objects on the metal surface is driven by two different waves: the SPP mode and a quasi-cylindrical wave that persists on the surface over a few wavelength propagation distance. We discuss the impact of these two waves in the extraordinary transmission.
Journal of Physics Conference Series 12/2008; 139(1):012001.
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ABSTRACT: The phenomenon of extraordinary light transmission through metallic films perforated by nanohole arrays at optical frequencies was first observed a decade ago and initiated important further experimental and theoretical work. In view of potential applications of such structures--for example, subwavelength optics, optoelectronics devices, and chemical sensing--it is important to understand the underlying physical processes in detail. Here we derive a microscopic theory of the transmission through subwavelength hole arrays, by considering the elementary processes associated with scattering of surface-plasmon-polariton (SPP) modes by individual one-dimensional chains of subwavelength holes. Using a SPP coupled-mode model that coherently gathers these elementary processes, we derive analytical expressions for all the transmission spectrum characteristics--such as the resonance wavelength, the peak transmission and the anti-resonance. Further comparisons of the model predictions with fully vectorial computational results allow us quantitatively to check the model accuracy and to discuss the respective impacts of SPP modes and of other electromagnetic fields on producing the extraordinary transmission of light. The model greatly expands our understanding of the phenomenon and may affect further engineering of nanoplasmonic devices.
Nature 05/2008; 452(7188):728-31. · 36.28 Impact Factor
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ABSTRACT: Using a scanning near-field optical microscope, we visualize, in three dimensions, the electromagnetic field distribution near an isolated slit aperture in a thin gold film. At the metal-air interface and for a TM incident polarization, we confirm some recently observed results and show that the slit generates two kinds of surface waves: a slowly decaying surface plasmon polariton and a quasi-cylindrical wave that decreases more rapidly when moving away from the slit. These waves are not generated for a TE incident polarization. In a noncontact mode, we also observe how the transmitted light diverges in free space. At a small distance from the slit (< 2 microm), we find that the emerging light spreads in all directions for TM, forming an electromagnetic cloud, whereas it is concentrated above the slit for TE, forming a more directive light jet. The experimental images are in good agreement with the numerical simulations.
Applied Optics 12/2007; 46(36):8573-7. · 1.41 Impact Factor
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ABSTRACT: Theories to calculate the propagation of arbitrary-order correlations of stationary or nonstationary partially coherent electromagnetic fields are proposed. The theories are based on separated-coordinate mode decomposition, and can make the well-developed propagation theories of fully coherent electromagnetic fields applicable to partially coherent electromagnetic fields governed by linear Maxwell equations. The validity of the theories is illustrated by an example.
Journal of the Optical Society of America A 03/2007; 24(2):368-78. · 1.56 Impact Factor
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ABSTRACT: Propagation theories of partially coherent electromagnetic fields based on coherent mode decomposition or separated-coordinate mode decomposition are proposed. With the proposed propagation theories, various powerful theories for the propagation of fully coherent electromagnetic fields can be used for the propagation of partially coherent electromagnetic fields. The proposed theories are applicable to any propagation problem of partially coherent electromagnetic fields governed by linear Maxwell equations. Some examples are provided to illustrate the validity of the proposed theories.
Journal of the Optical Society of America A 10/2006; 23(9):2208-18. · 1.56 Impact Factor
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ABSTRACT: We report design theories of a diffractive superresolution element (DSE) to implement optical superresolution of focused partially spatially coherent laser beams. The design problem of the DSE can be transformed into a problem of linear programming to obtain a globally optimal solution. By using the design theories, some fundamental limits of optical superresolution of focused partially spatially coherent laser beams are proposed, and several design examples are provided. As expected, both the fundamental limits and the design examples show that worse spatial coherence will cause worse superresolution performance. The design theories provide a design approach with partially coherent beams and may be useful for other design problems under partially coherent illumination.
Journal of the Optical Society of America A 07/2006; 23(6):1301-10. · 1.56 Impact Factor
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ABSTRACT: Theories of a technique for compression of an ultrashort femtosecond laser pulse beyond its Fourier-transform limit based on the pulse shaping technique are proposed. The technique is called superresolution in time domain (STD). Global optimization theories for the design of a mask to modulate the spectrum of an input pulse to obtain a STD output pulse are proposed. Several design examples illustrate the feasibility of STD. Some fundamental limits of STD are also provided.
Journal of the Optical Society of America A 05/2006; 23(4):848-57. · 1.56 Impact Factor
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Physical Review B.
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IEEE Journal of Selected Topics in Quantum Electronics.
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OSA-IEEE Topical Meeting on Advances in Optoelectronics & Micro/Nano-optics.
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France-US Workshop on Nanophotonics.
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Metamaterials and their applications (MetaIn-2008).
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92th OSA Annual Meeting Frontier in Optics.
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Fourth International Conference on Surface Plasmon Photonics (SPP4).
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9th International Conference on Photonic and Electromagnetic Crystal Structures (PECS IX).
