COL 12(10), 101601(2014) CHINESE OPTICS LETTERS October 10, 2014
1671-7694/2014/101601(5) 101601-1 © 2014 Chinese Optics Letters
In the past three decades, there has been a consider-
able interest in the tunneling of electromagnetic (EM)
wave for its practical applications in many various
aspects. With the advancement in the eld of meta-
materials, many unusual physical properties have
been exhibited
[1–5]
and the tunneling in metamateri-
als has attracted signicant attention
[6,7]
. The meta-
materials include double-negative and single-negative
(SNG) materials
[8,9]
. SNG material with negative rel-
ative permittivity (e-negative (ENG)) or negative
relative permeability (m-negative (MNG)) should be
opaque media because the EM wave is evanescent. Un-
der proper conditions, the tunneling through certain
structures consisting of one or more SNG materials
can be achieved
[10–15]
.
Recently, non-radiative EM transfer, enabling ei-
cient and safe wireless energy transfer has received sub-
stantial interest
[16–21]
. This proposed scheme is based on
magnetic resonances (the fact that two same frequency
resonant objects tend to couple, while interacting weak-
ly with other o-resonant environmental objects) and
resonant evanescent coupling through the overlap of the
non-radiative near elds of the two objects. Magnetic
resonances are particularly suitable for everyday appli-
cations because most of the common materials do not
interact with magnetic elds, so interactions with envi-
ronmental objects are suppressed even further. There
is a strong EM coupling between resonant objects, but
the coil-based systems are bulky in order to reach high
eiciencies.
Recently, research on radiative and non-radiative en-
ergy transfer in metamaterial has been reported
[22,23]
.
The possible application of wireless energy transfer
with a sandwich structure consisting of MNG medium,
air, and ENG medium was investigated
[23]
. The distribu-
tion of electric and magnetic elds in some tunneling
structure consisting of SNG media or double-positive
(DPS) media can be controlled
[24–27]
. Inspired by the tun-
neling of EM wave and eld modication in SNG mate-
rials, we investigate a dierent scheme of non-radiative
energy transfer in a multi-layer structure similar to
Feng et al.
[23]
. The dierence is that we have placed two
pairs of ENG/MNG couple layers on the two ends and
there is one more DPS layer on the incident side of air.
The results show our structure is superior and control-
lable because of the following reasons: 1) the magnetic
eld is enhanced and the stronger magnetic eld is lo-
cated on the receiving terminal; 2) the DPS material
accelerates the decay of the electric eld, so the electric
eld in the air is small; 3) the energy of tunneling ends
if the receiving terminal is removed.
The geometry is illustrated in the Cartesian coordi-
nate system (
and
) of Fig. 1. Without loss of
generality, we consider a multi-layer structure in air.
A, B, C, and D represent ENG medium, MNG me-
dium, DPS medium, and air, respectively. e and m are
relative permittivity and relative permeability of me-
dia. Here each slab (including DPS) is isotropic, lin-
ear, and homogeneous. We assume the problem to be
Electromagnetic tunneling through conjugated
single-negative metamaterial pairs and
double-positive layer with high-magnetic elds
Yuanyuan Chen (陈园园)
*
, Shanhong Huang (黄闪红), Xiaona Yan (阎晓娜),
and Jielong Shi (施解龙)
Department of Physics, Shanghai University, Shanghai 200444, China
*
Corresponding author: cyyuan@sta.shu.edu.cn
Received April 10, 2014; accepted June 18, 2014; posted online September 28, 2014
We show that resonant tunneling of electromagnetic (EM) elds can occur through a six-layer structure con-
sisting of two pairs of bilayer slabs: one being an epsilon-negative layer and the other being a mu-negative
layer with a double-positive (DPS) medium and air. This type of tunneling is accompanied by high-magnetic
eld. The Poynting vector distributions and the material dissipation are studied. Our results demonstrate
that the EM eld in the structure is controlled exibly by single-negative media and DPS slab. Therefore,
this structure has potential applications in wireless energy transfer.
OCIS codes: 160.3918, 240.7040.
doi: 10.3788/COL201412.101601.
Fig. 1. Heterostructure containing SNG materials in air.