Some considerations on the transmissivity of thin metal films
Hooper, Ian R.
Sambles, J. Roy
University of Exeter
Optical Society of America
As interest in plasmonics grows the optical properties of thin metal films becomes increasingly significant. Here we explore the transmissivity of thin metal films at normal incidence, from the ultraviolet to microwaves, and show how, contrary to simplistic treatments, the microwave transmissivity may be much less than the optical transmissivity for films which are well below the skin depth in thickness. This arises because the film is acting as a zero order Fabry-Perot with very high reflectivity at each interface. The skin depth then becomes irrelevant for thin metal films at microwave frequencies. We also note in passing that the expected exponential dependence on thickness at higher thicknesses has an asymptotic limit at zero thickness which may be as high as four times the input intensity.
Copyright © 2008 Optical Society of America. This paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-22-17258 . Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.
16 (22), pp. 17258-17268