Light Manipulation by Metamaterials

W. J. Sun, S. Y. Xiao, Q. He*, L. Zhou

Physics Department, Fudan University, Shanghai 200433, China

*Speaker: qionghe@fudan.edu.cn

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

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 velocities (theory ~ expt.)

propagating wave (z direction) surface wave (x-y plane)

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

Slow light promotes stronger

light–matter interaction

Absorption

00

Nonlinear optics

Applications

• 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

Basic Results (Expt. ~ Theory)

Perfect absorption for both TE and TM polarizations

~ 19 h

Omnidirectional/polarization insensitive

Perfect agreements between Theory & Expt.

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

Thanks