Recently, the problem of EM field distribution for long and thin
nanometer-sized needles (nano-wires) has attracted growing interest
(see, e.g., [1]). We consider metal needles, whose diameter is much
smaller than the wavelength of incident light, and whose length is of
the order of the wavelength. The electromagnetic field distribution
for nanowires is found, by using the discrete dipole approximation
beyond the quasi-static approximation as well as analytical solution
for a plasmon localized in a nanowire [2]. By using these approaches
we simulate the field distribution for individual nm-sized metal
needles and for a percolation composite formed by such needles. For
individual needles, it is found that the surface plasmon polaritons
can be excited, resulting in large local fields. For percolation
composites formed by the needles, our simulations suggest localization
of the plasmons and strong local field enhancement associated with
these localized plasmons. The theory is in agreement with the
near-field optical experiments performed by Moskovits' research
team in UCSB [3].
We also show that in plasmonic composite nanomaterials both dielectric
permittivity and magnetic permeability can be negative, opening up new
means for fabricating left-handed materials [2], with the negative
refractive index in the visible and near-infrared parts of the
spectrum. Specifically, such optical left-handed materials can be
fabricated, using metal nano-wires or metal-dielectric percolation
composites [2,4].
References:
1. S. D. M. Brown, P. Corio, A. Marucci, M. A. Pimenta, M. S.
Dresselhaus, and G. Dresselhaus, Phys. Rev. B 61, 7734 (2000)
D. P. Makhnovskiy, L. V. Panina, D. J. Mapps, A. K. Sarychev, Phys. Rev. B
64, 134205 (2001).
2. V. A. Podolskiy, A. K. Sarychev, and
V. M. Shalaev, J. Nonlinear Optical Phys. and Mat. (in press)
A. N. Lagarkov and A. K. Sarychev, Phys. Rev. B 53, 6318 (1996).
3. S. Y. Yang, V. A. Podolskiy, V. Ushchinnskaya, L. -L. Tay, T. Haslett,
A. K. Sarychev, M. Moskovits and V. M. Shalaev (submitted).
4. A. K. Sarychev, R. C. McPhedran, and V. M. Shalaev, Phys. Rev. B 62,
8531 (2000) A. K. Sarychev and V. M. Shalaev, Phys. Reports 335, 275
(2000).