Download Applied Electromagnetics

Applied Electromagnetics
Silvio Hrabar
Faculty of Electrical Engineering and
Computing, University of Zagreb, Croatia
The Course Structure
Part I
Artificial electromagnetic materials
Part I
Metamaterial-based guiding structures
Part III
Metamaterial-based antennas and scatterrers
Part IV
Active Metamaterials
Part V
New directions
Part V
New directions in Metamaterials
• Going optical (From RF to ‘plasmoncs’)
• Going nano (From electronics to ‘metatronics’)
• Going ‘carbonical’ (From CNT to graphene)
• Going beyond electromagnetics (from acoustics to
black holes)
• Conclusions
Going optical (From RF to ‘plasmoncs’)
Going Optical – Approach I
Scaling Down the Size of Inclusions
Going Optical – Approach II
Make Use of Surface Plasmons
The Lycurgus Cup (glass;
British Museum; 4th
century A. D.)
Going Optical – A ‘Soft’ Approach
Make Use of Surface Plasmons
Permittivity of silver
Thesurfaceplasmonresonance
Metallicsphereembeddedindielectrichost:
Eo
εεinin
absorption (a. u.)
ε0
electron
sphere
10
9
8
7
6
5
Ag + SiO2
Au + SiO2
Cu + SiO2
4
3
2
1
200
400
600
wavelength /nm
800
Theplasmonicresonanceofa
nano‐sphere
low frequency
high frequency
Localfieldinsidethesphere:
Ein 
3ε0
E0
εin  2ε0
Resonancecondition: ε i +2ε 0
0
•Waveguiding Applications in Optical Regime
•M. Quinten et. al. ‘Electromagnetic energy transport via linear chains of
silver nanoparticles’ (Optics Letters, Vol. 23, No. 17, 1998)
•S. Maier, P.G. Kik, H.A. Atwater, ‘Optical Pulse Propagation in Metal
nanoparticle Chain Waveguides’ (Phys. Rev. B , 2003)
•L
•T
•T
•All figures copied from the original articles
Other potential applications in optical domain
1D Backward-wave and
plasmonic
Forward-wave
Nano-transmission lines
and nano-antennas
Alu and Engheta;
JOSA B, March 2006
Non-plasmonic
2 D Backward-wave
and Forward-wave ‘flatland’ structures (e.g.
super lenses)
Backward-wave and forwardwave 3 D metamaterials ;Alu and
Engheta, Phys. Archive 2006
Ensembles of plasmonic nanospheres at optical
frequencies and a problem of negative
index behavior
E.V. Ponizovskaya and A.M. Bratkovsky
http://arxiv.org/abs/cond-mat/0701186v1 (2007)
New Idea - Scaled RF Replicas of
Plasmonic Structures
What is electrical engineering interpretation of a plasmonic
(i.e. ENG ) nano-sphere (Engheta et. al. IWAT 2005)
P
P
How to obtain the negative electric polarizabilty using a simple
inclusion in RF and microwave regime ?
real part
εr
R
C
Einc
Z
Es ca t
V=L
o ef E in
Za
+
Z
Imaginary
L
0
part
1
0
I
f0
f pmp
f
•D.R. Smith et. al. :‘Loop-wire medium for investigating plasmons at
microwave frequencies’, App. Phys. Lett., Vol 75, No. 10, 1999 )
An ideal ENG sphere
H. A. Wheeler, “Fundamental limitations of small antennas,”
Proc. IRE, vol. 35, pp. 1479–1484, 1947
H. A. Wheeler, “The spherical coil as an inductor, shield, or
antenna,” Proc. IRE, vol. 46, pp. 1595–1602, 1958
S. R. Best, “The radiation properties of electrically small
folded spherical helix antennas,” IEEE Trans. Antennas
Propag., vol. 52, pp.953–960, 2004
An ideal ENG sphere
H
Ein
I
Prototyping of ‘RF replicas’ of plasmonic spheres
(Hrabar et.al., IEEE AP-S, 2007)
diameter = 5.8 cm
Best’s spherical resonator
Simulated E-field distribution
Measurement of E-field phase distribution along
four-sphere chains (RF replicas of plasmonic WG)
0
1
20
-100
Phase[degrees]
L
Measuring points
FW
-200
-300
-400
-500
0
solid: simulated;
dashed: measured
5
10
15
20
Measuring point
Phase[degrees]
400
T
1
Measuring points
20
300
solid: simulated;
dashed: measured
200
BW
100
0
0
5
10
Measuring point
15
20
Full-wave simulation of the electric field distribution
along the chain (T polarization)
How to test a phase reversal of E field ?
(Hrabar et.al. Nanometa 2009)
f0~208 MHz,
diameter~18 cm (~0.12λ)
Measurement of the
phase of S21
Point 1
Point 2
Incoming
plane wave
It is difficult to assure a plane
wave illumination !
Phase 2-phase 1= 192 degrees
Measurement using a quasi static excitation with
homogenous E-field (d = 20 cm, f=150 MHz)
Parallel plate capacitor
Spherical resonator
Parallel plate capacitor Linear taper Linear taper
Best’s spherical resonator Balun
Imaginary
0
part
1
0
f0
f pmp
f
x
Phase difference[degrees]
εr
x
180
real part
x
x
simulations
120
measurements
60
x
0
0.05
x
0.1
0.15
0.2
0.25
Frequency[GHz]
x
0.3
x
0.35
0.4
D
 H  J 
,
t
•This ‘nano-cluster’ is actually a SRR with
circulating displacement current !
•Is it possible to construct
an RF analog of
‘plasmonic circular cluster
’?
•Not fully, due to inherent
anisotropy of RF replicas
of plasmonic nano –
spheres…
•But, it should be
possible to
experimentally prove the
basic principle !
How to test an RF analog of ‘plasmonic circular cluster ‘?
Subwavelength SRR-based Waveguide
•(Marques et.al. 2002, Hrabar et.al. 2003)
Transmission coefficient[dB]
0
-10
-20
-30
-40
-50
-60
-70
-80
0.45
0.5
0.55
0.6
Frequency[GHz]
0.65
0.7
•Animation of simulated distributions of
x-oriented component of the magnetic
field at 484 MHz
•RF
•c
•Feeding
waveguide
•Collections of four
Best's resonators
•Feeding
waveguide
•Is it possible to construct isotropic RF analog of
‘plasmonic nanosphere ‘?
•Prototyping and measurement of isotropic
•RF analog of ‘plasmonic nanosphere ‘
•0 degrees
(x and y)
•45
degrees (x
)
•45
degrees (y
)
Near-field Superlens

 
E
 H  J 
t


H
  E  
t
Near-field Superlens
Experimentally achieved images
N. Fang, H. Lee, C. Sun, X. Zhang, Science 308, 534, (2005).
written object (top)
optical image (center)
optical image without
super- lens
Problem 2 All these structures have significant loss !
What could be an appropriate gift for
tenth birthday?
n’/n’’=8
Going nano (From electronics to ‘metatronics’)
Presentation slide by N. Engheta
Presentation slide by N. Engheta
Presentation slide by N. Engheta
Presentation slide by N. Engheta
Presentation slide by N. Engheta
Presentation slide by N. Engheta
Scaled prototype of optical D-dot wire (Muha, Hrabar et al. 2011)
• Going ‘carbonical’ (From CNT to graphene)
Carbon Nano-tubes (CNT)
Graphene-based One-atom-thick Metamaterials
Figures taken from N. Engheta presentation slides
Graphene-based Metamaterials
Figures taken from N. Engheta presentation slides
Going beyond electromagnetics
(from acoustics to black holes)
(Shu Zhang, Ph.D. thesis) 2005)
Acoustic TL metamaterial
(Shu Zhang, Ph.D. thesis) 2005)
Acoustic TL cloak
What’s next?
• Nanotechnology + metamaterials (plasmonics,
,photonics, lasing, gain materials, superluminal
materials, graphene, nano-spheres and nanofilms)
• One might not have all necessary
technology in nano-science, but basic
physical principles and ideas surely can be
verified with minimal investment