Localization and absorption of the local field in two-dimensional composite metal-dielectric films at the percolation threshold

Abstract

We study in this paper the localization of the electric field and the dielectric properties of thin metal-dielectric composites at the percolation threshold. In particular, the effects of the loss in the metallic components are examined. To this end, such systems are modelled as random RL -C networks, and the local field distribution as well as the effective conductivity are determined by using an exact resolution of Kirchhoff equations in addition to a real-space renormalization group method for comparison. We find a delocalization of the eigenmodes which remain weakly localized for vanishing losses. This result seems to be in agreement with the anomalous absorption observed experimentally for such systems.

Plasmon localization and local field distribution in metal-dielectric films

“…The two new block elements h (25) and h (52) appeared due to the interactions of the first row with the second and the fifth rows. As a second step, we apply the above procedure for the minor Ĥ 11…”

Coexistence of Localized and Delocalized Surface Plasmon Modes in Percolating Metal Films

“…Such interactions can lead to spatial localization of electromagnetic energy at subwavelength scales and giant local field fluctuations [5][6][7][8][9]. Near-field intensity statistics have been obtained numerically [7][8][9][10][11] and experimentally [12,13] to characterize the local field fluctuations in various metal aggregates, fractal structures, rough and semicontinuous metal films. The probability density function of intensity enhancement in the multiple scattering regime is shown to be distinctly different from that in the single scattering regime [12].…”

“…The variance of intensity fluctuations is proportional to the inverse participation ratio of the local field R IP , often used to describe the spatial extent of eigenstates [10,11]. In the current experiment where the incident field excites a number of SP modes, R IP gives a qualitative measure of the surface area occupied by hot spots.…”

Near-Field Intensity Correlations in Semicontinuous Metal-Dielectric Films

“…These properties are very different from those in a dielectric random system where the speckle pattern is relatively more homogeneous with an average speckle size of the order of . Moreover, the accumulation and subsequent dissipation of EM energy in localized SP modes result in anomalous absorption in semicontinuous metal films [13][14][15]. These fundamental differences between metallic and dielectric random systems suggest that the near-field intensity correlation functions in these two systems can be dramatically different.…”

“…The drop is much sharper at p 0:65, and Cx; 0 is almost zero when x > 0:5 m. At p 0:83, the decrease becomes gradual again and Cx; 0 remains well above zero even for x > 3 m. The long tail of Cx; 0 suggests the existence of long-range correlation at low and high p, which results from a delocalized field. In the intermediate regime of metal concentration, the rapid decay of Cx; 0 to zero indicates that the intensity correlation becomes short ranged because of strong scattering and anomalous absorption[13][14][15]. The correlation radius R c [HWHM of Cx; 0] allows a quantitative comparison between different samples and is plotted in the inset ofFig.…”