On the electrodynamics of an absorbing uniaxial nonpositive determined (indefinite) medium
- PDF / 233,154 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 87 Downloads / 144 Views
OLECULES, OPTICS
On the Electrodynamics of an Absorbing Uniaxial Nonpositive Determined (Indefinite) Medium D. G. Baranova, A. P. Vinogradova,*, K. R. Simovskiib, I. S. Nefedovb, and S. A. Tret’yakovb a
Institute of Theoretical and Applied Electrodynamics, Russian Academy of Sciences, Moscow, 125412 Russia b Department of Radio Science, School of Electrical and Electronic Engineering, Aalto University, FI00076, AALTO, PO Box 13000 Finland *email: a[email protected] Received May 24, 2011
Abstract—It is shown that a surface plasmon, whose decay length infinitely increases as it approaches the threshold frequency, can propagate over the surface of a halfspace filled with a uniaxial indefinite absorbing metamaterial. At the threshold frequency itself, a new phenomenon is observed—upon incidence of a TM polarized wave on the absorbing material, a real Brewster angle exists, and in the case of a plate made of such a metamaterial, “reflectionless” reflection is observed when two plane waves are incident on the plate from two sides. In the latter case, complete destructive interference of reflected and transmitted waves occurs. DOI: 10.1134/S106377611202001X
1. INTRODUCTION
flux. Below, we will call such a surface wave having a
Recently there has been much interested generated by phenomena related to excitation of surface plasmons, unified under the general term plasmonics [1–9]. A characteristic feature of plasmonics differentiating it from common optics and UHF electrodynamics is that fact that all events in plasmonics unfold at scales much smaller than the wavelength in vacuum. This imparts plasmonics with many nearfield optics fea tures and makes it integral to modern nanotechnolo gies.
similar energy flux distribution a typical plasmon. A surface plasmon can be observed in the optical range on the surface of noble metals, the real part of the permittivity of which is negative [1–4]. However, the permittivity of real metals has a finite imaginary part (ε = ε' + iε''), as a consequence of which the wave vector kpl also has an imaginary part: kpl = k 'pl + i k ''pl ; therefore, when a surface plasmon propagates along the surface, it decays with a characteristic decay length l = 1/Im(kpl(ω)). For the boundary of silver with a free space at a wavelength of 400 nm, the decay length (or the propagation length) is of the order of 50 μm, which is insufficient for many practical applications. It is known that above the surface of an anisotropic metamaterial with a socalled indefinite permittivity in addition to a typical surface plasmon, an atypical surface plasmon can also propagate [2, 12]. The per mittivity tensor εˆ of the anisotropic medium is called indefinite [13] if its components in the principal axes have different signs of the real part. A distinctive fea ture of an atypical surface plasmon is the fact that the Poynting vector in both media is directed to one side [2, 12]. Below we show that a surface plasmon whose decay length infinitely increases when the threshold fre quency is approached can propa
Data Loading...
