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| Attenuation of light by sub-wavelength apertures | Prev topic | Next topic Fig. 1 |
Light incident onto a metal film that is perforated with an array of nanoholes, each with a diameter smaller the wavelength, behaves in a surprising way: more light is transmitted than that incident onto the combined nanohole area within the light beam footprint. This effect, termed the extraordinary optical transmission (EOT) (Figure 1), is even more surprising considering that the nanoholes have subwavelengh diameters and do not support direct transmission of light [any propagative modes] (Ebbesen TW et al 1998). Note that the array does not to be periodic (for example, Matsui T et al 2007).
The EOT is an interesting manifestation of interaction of light (scattering) with material containing voids and complements light scattering by particles of the material (i.e. voids containing material). The EOT has potential applications in subwavelength patterning (for example, Alkaisi MM et al 1999), optoelectronics devices (for example, Liu C et al 2005) and chemical sensing (for example, Genet C and Ebbesen 2007).
All salient features of the EOT can be reproduced with a microscopic model of interaction of light with an array of nanoholes (Liu H and Lalanne 2008). This model shows that the EOT is due to two kinds of surface waves: (1) the those due to surface-plasmon-polaritons (SPP; Raether H 1988) as initially envisioned by Ebbessen TW et al 1998 and (2) a quasi-cylindrical wave (CW) that creeps on short-range distances along [on] the upper and lower surfaces of the metal film before interacting with the [neighboring] nanoholes. At optical frequencies (short wavelength), both kinds of waves contribute equally to the EOT phenomenon, but at longer wavelengths, the metal conductivity increases and the SPP contribution is negligible (Liu H and Lalanne 2008).
| CITATION: Lalanne P. 2008. Attenuation of light by sub-wavelength apertures (www.tpdsci.com/Tpc/AtnSwaApt.php). In: Top. Part. Disp. Sci. (www.tpdsci.com). |
HISTORY: Published: 28-Aug-2008 Modified: 29-Oct-2008 Peer-reviewed: PENDING |
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