Physics Department, Fudan University, Shanghai 200433, China · Science 308,534(2005) Invisibility...
Transcript of Physics Department, Fudan University, Shanghai 200433, China · Science 308,534(2005) Invisibility...
Light Manipulation by Metamaterials
W. J. Sun, S. Y. Xiao, Q. He*, L. Zhou
Physics Department, Fudan University, Shanghai 200433, China
*Speaker: [email protected]
2011/2/19
Outline
Background of metamaterials
Manipulate light polarizations by metamaterials
Slow-wave meta-surfaces to enhance light-matter interactions
Conclusions
Outline
Background of metamaterials
Manipulate light polarizations by metamaterials
Slow-wave meta-surfaces to enhance light-matter interactions
Conclusions
Artificial media structured on a lattice size scale smaller than wavelength, which enable us to design our own “atoms” and create materials with
exotic optical properties and new functions, which do not exist naturedly.
Metamaterials
ε
1
Some ferromagnetic andantiferromagnetic
materials
Metal
μNatural material phase diagram
atomsMeta-atoms
Materials Meta-materials
MTMs: Powerful tools to manipulate EM wave
Subwavelengthimaging
Science 308,534(2005)
Invisibility (Cloaks)
Science 314, 977(2006)Science 312, 1780(2006)
hhh
Negative refraction
PRL 76, 4773 (1996)Science 292, 77(2001)
Recent works of our group
Perfect transparency of ABA structure
P.R.L 97,053902 (2006)P.R.L 94,243905 (2005)• Evanescent wave amplified in opaque B layer• Effective medium idea • Demonstrated by microwave experiment
Fractal MTM lens realize Sub-wavelength Imaging
Huang, et. al., OE 18, 10377(2010)
Metallic plate with fractal shaped slits
-50 0 500.0
0.5
1.00.0
0.5
1.0
x (mm)
H=63mm(c)
Nor
mal
ized
E-F
ield
s
(b)H=31.5mm
• Independent of lens thickness• Possible to transport through a
long distanceImage resolution ~ /15
119mm
Outline
Background of metamaterials
Manipulate light polarizations by metamaterials
Slow-wave meta-surfaces to enhance light-matter interactions
Conclusions
Conventional methods to manipulate polarization
Wire-Grid Polarizer
Birefringent crystals
Wave plate
Our motivations:• Ultra-thin MTM
(much thinner than )• 100% efficiency
Problems:
• Energy loss issue• Size issue
Our Previous attempt :Control polarization with MTM reflector
• Polarizations completely converted (TE to TM), 100% efficiency• Any polarization (linear, circular, elliptical) is realizable • Good agreements between theory & experiment• Physics: PEC for one polarization and PMC for another
PRL 99,063908 (2007); PRB 77, 094201 (2008) ;PRA 80, 023807 (2009)
Problems & Solutions
• Previous attempts for transmission geometry:
T. Li et. al., APL 93 021110 (2008) J. Y. Chin, et. al., APL 93 251903 (2008)
Our motivationa transparent ultra-thin MTM Phase Plate!
• Interference issues in reflection configuration
no perfect transmission!
Designed MTM structure
pg
E
l 2h
he
d
ab
a
2a
fX
YZ
A layer
B layer
ABA
(a)
(b)
(c)
12 , 10 , 21.3 , 9 , 11 , 1 , 0.6a mm b mm g mm e mm p mm l mm h mm
, Anisotropic electric MTM
Metallic mesh
Transmission spectrum (simulation)
0.0
0.5
1.0
1 4 70
4
8(a)
d = 3mm
TMM
FEM
Frequency (GHz)
|S21
|
1st 2nd 3rd
(b)
1st & 2nd
3rd
TMM
d (m
m)
• Several total transmission peaks • First two are EMT solutions • 3rd one can not be explained by EMT!
2 220.2 1917 5.47xA f
24.483 623.1B f
EMT parameters for A & B layers
What’s the origin for the 3rd peak ?
Origin of the 3rd peak
• Extraordinary optical transmission (EOT)
Ebbson. et. al, P.R.B, 58 ,6779(1998)
Surface plasmons enhance optical transmission through subwavelength holes
Origin of the 3rd peak - EOT
• SPP exists on “B” layer
• “A” layer provides a reciprocal G vector
• Momentum matching Perfect transparency of EOT origin
TM SPP
Independently Tunable peaks
0.0
0.5
1.0
-180
0
180
1.0 4.5 8.00.0
0.5
1.0
1.0 4.5 8.0-180
0
180
FEM Expt.
(a) (c)
||E Y
||E X
(b)
Frequency (GHz)
|S21|
(d)
EOT, small
EMT, high large
Perfect transmissions with large phase difference !
Polarization manipulation effects
• Flexible control of polarization in transmission configuration
• (nearly) lossless, 100% efficiency
• System is only thick
• Good agreement between theory and expt.
Sun. et. al, OL, accepted (2011)
Ultra-thin microwave phase plate
Outline
Background of metamaterials
Manipulate light polarizations by metamaterials
Slow-wave meta-surfaces to enhance light-matter interactions
Conclusions
Why do we need slow light ?
Faster is not always better
Using light smartly rather than simply relying on its speed offers many opportunities. Slow light promotes stronger light-matter interaction. T. F. Krauss et al, Nature Photon. 2,448-449 (2008)
Recent approaches to achieve slow waves
EIT Photonic Band Gap
L. V.Hau et al, Nature. 397,594-598(1999) T. Baba et al, Nature. 2,465-473 (2008)
Available mechanisms to realize slow waves
gdvdk
BULK EFFECT
RESONENCE
atom
L. V.Hau et al, Nature. 397,594-598(1999)
BAND GAP
T. F. Krauss et al, Nature Photon. 2,448-449(2008)
Motivation
Find an ultra-thin system to support slow-waves along all directions?
No Bragg scanning, no F-P effect, how to slow down the wave with Meta-surface?
Fastlight
Our slow-wave meta-surface
1
2 3 4
20 , 105 , 2
a mm l mml l l mm w mm
1 22 , 2h mm h mm
metal airh1 h2
inputFast Light
outputFast Light
SlowLight
Slow light
Demo(C)
Metallic plate with fractal-like shaped
slits
Group velocity can be further reduced !
• Counter intuitive --- the smaller w, the more metal!• The thickness is ultrathin ~ /19
Physical mechanism for slow wave
0 Waveguide Cut-off
0z
ddk
0x
ddk
Prop
. wav
eSu
rf. w
ave
Dispersion Groupvelocity • Waveguide
cutoff mode is a slow-wave mode, independent of h
• SPP facilitates perfect coupling of fast light to slow light: deep subwavelength & high Q factor
z direction
In xy plane
• Slowing wave compresses wave-packet longitudinally• Squeezing into apertures laterally
matter
FasterLight
FasterLight
SlowLight
HighIntensity
Slow-wave meta-surface to enhance light-matter interaction
Strongly enhancelight-matter interaction
airh1 h2
0
20Strong local field
Example 1: Perfect absorber
(A)2D geometry
(B) 3D view
1
2 3 4
20 , 105 , 2
a mm l mml l l mm w mm
1 22 , 2h mm h mm
4
metallossy materialsFR PBC
1 2
1 2 3 4
70070
2 2 2 350
a nmw h h nml l l l nm
Ag
InSb (Kerr nonlinearity)
15 1
12 1
2 2.175 10
2 20 10p s
s
(3) 6 34, 2 10 /linearn erg cm
2
2p
i
Example 2: Slow-wave enhances nonlinear effect
• Infra-red regime• Theoretical prediction
Enhanced THG by MTM (FDTD simulation)
• 4-5 orders in magnitude enhancements can be easily obtained
10 m Working wavelength:
Conclusions• Ultra-thin metamaterial phase plate to control
light polarizations efficiently with perfect transmittance
• Slow-wave meta-surfaces to enhance light-matter interactions - perfect absorption and enhanced nonlinear response
•W. J. Sun, et. al., OL, accepted (2011)• S. Y. Xiao, et. al., Unpublished
• J. M. Hao C. T. Chan X. Q. Huang (HKUST) S. Y. XiaoWujiong Sun L.Zhou(Fudan)
• China-973 ProjectNSFC, Shanghai Sci. Tech. Committee
Acknowledgements