Biomedical Engineering Reference
In-Depth Information
The electromagnetic energy vortex could be separated into an
inner part and an outer part, with the corresponding Poynting
vectorsexpressedasE
||
×
H
Z
and E
Z
×
H
||
, both fields being
produced by surface charge and surface current; here, E
||
=
E
X
x
+
E
Y
y
and H
||
=
H
X
x
+
H
Y
y
. In Fig. 13.6b and 13.6e, the
distribution of H
Z
is shown as a color bar and the direction of E
||
as purple arrows; their cross-product gives rise to the inner vortex
associated with the Taiji pattern. Similarly, E
Z
×
H
||
produces the
outer vortex.
ThespectralpropertiesaredominatedbythetailofTaijipattern.
The hole and the dot of Taiji pattern show a limited change as
shown in Fig. 13.7. The dot of Taiji pattern only slightly changes the
Figure 13.7
Simulation transmittance spectra for various diameter of
nanohole under (a)
x
-polarized and (b)
y
-polarized illumination. Pur-
pure arrow denotes the direction of electric field. (c)
x
-polarized and
(d)
y
-polarized illumination for comparing the plasmonic Taiji mark
with/without gold dot. The insets show the designed pattern of plasmonic
Taiji mark without gold dot and polarization state.
