Transcript Slide 1

ILPB Metamaterial Research
SUNY at Buffalo
Department of Chemistry
“Lighting the Way to Technology through
Innovation”
The Institute for Lasers Photonics and Biophotonics
www.photonics.buffalo.edu
Overview
 Basic Metamaterial Concepts
 ILPB Capabilities
 ILPB NIM Group
 ILPB Metamaterial Research
• Approaches to NIM fabrication
• Experimental and Experimental Results
Publications and Presentations
Electromagnetic Material Properties
The electromagnetic response of a material is defined by its
electromagnetic properties: permittivity  and permeability 

Plasmas
  0,   0
no transmission
Negative Index
Materials
Conventional
Materials
  0,   0
n   
Split Rings
  0,   0
  0,   0
n   
no transmission

Metamaterials
Metamaterials: artificially engineered materials possessing
electro-magnetic properties that do not exist in naturally
occurring materials.
n>0
Normal water
 = 1.7,  = 1
NIM water*
 = -1.3,  = -1.3
Light deflection
*Gunnar Dolling, et. al., Opt. Exp.14, 1842 (2006)
n<0
Light focusing
Perfect Lens (Pendry, 2000)
ILPB Metamaterial Research/Development
Capabilities
Modeling - Design - Fabrication - Characterization
PLASMONICS
Nanoparticles
Nanostructure Media
NANOPHOTONICS
Materials - Devices
Systems
Metamaterials
NIM Applications
Novel Photonic Devices
Characterization Facilities
Macroscopic Scale
• CD spectroscopy
• Interferometry
• Reflectometry
ILPB NIM Group
• Prof. Paras N. Prasad – Nanophotonics, Photonic Devices and Materials
• Prof. Edward Furlani – Multiphysics and Photonics Modeling, Device Physics
• Dr. Alexander Baev – Multiscale Modeling, Material and Device Physics
• Dr. Heong Oh - Polymer Chemistry/Chiral Media
• Researcher Rui Hu – Materials Synthesis and Characterization
• Researcher Won Jin Kim – Polymer Chemistry, Material Synthesis
• Researcher Shobha Shukla - Lithography for Nanostructured Media
ILPB Metamaterials Research
ILPB is pursuing a bottom-up approach to NIM fabrication
Bottom-up approach:
Chiral NIM Media
Top-down approach
Resonant Metallic Nanostructures
(Chemical Synthesis/Assembly)
(Lithography)
Chiral molecules doped with
plasmonic nanoinclusions
neff     ,  1
Achieves  < 0,  < 0 from EM coupling
between paired plasmonic elements
Chiral Media Development
Selected model structures:
Helical polyacetylenes
Theoretical modeling:
Preliminary quantum chemical and EM modeling
predicts enhanced chirality and lowered permittivity
Plasmonic nanoparticles attached
to chiral components lower
dielectric permittivity
O
O
HO
NH2
+
R
O
HN
CH3
i
H O
HN
H
CH3
ii
H
O
R
Br
M
CH3
O
R: -H, -N(CH3)2, or -NO2
R
i) N,N'-dicyclohexylcarbodiimide in methylene chloride
ii) triethylamine, CuI, PdCl2 (PPh3)2, PPh3 in 1,4-dioxane
M
iii
iii) MoCl5-Ph4S in toluene
n
NH
H
O
O
*
*
20
*
20
*
O
HN
O
P1
NH
Proposed synthetic route to chiral components
Basic Chiral Media Relations
neff  ncomposite   composite
ncomposite  nhost  nplasmonic
Current Status of Chiral Media Properties
nplasmonic = 0.5
composite = 10-2
Target Properties for next year
nplasmonic ~ 1
composite ~ 5 x 10-1
Materials Development
Objectives:
1. Development/characterization of composite material with lowered
refractive index.
2. Development/characterization of composite material with enhanced
chirality.
Strategy:
1. In-situ generation of gold/silver nanoparticles to obtain a high
load in the host material.
2. Synthesis of molecular units with high chirality and its polymeric
helical form.
3. Characterization.
4. Multiscale modeling and feedback.
Realization:
The use of photochemical decomposition of noble metal precursors
to generate plasmonic particles loaded composites.
PVP host doped with silver nanoparticles. Suppression of the
refractive index on the high energy side of plasmonic resonance.
n = 0.5
1.9
R efractive index (n)
1.8
G lass
PVP
1.7
S 2(P V P -A g)
1.6
S 6(P V P -A g)
S 7(P V P -A g)
1.5
S 3(P V P -A g)
1.4
S 8(P V P -A g)
n
S 4(P V P -A g)
1.3
l = 337 nm
1.2
200
700
1200
W avelength (nm )
1700
Approaches planned for enhancing the load
Higher load of NPs may be possible with:
1. Using direct mixing in the organic phase. Example:
PMMA host doped with gold nanoparticles prepared in
chlorobenzene.
2. Using templates with high density of binding sites.
3. In-situ generation by two-photon lithography.
4. Using nanoparticles of different morphology
i. Nanorods.
ii. Multipods.
iii.Core-shell structures.
TEM image of gold nanoshell
TEM image of gold nanorods
Plasmonic band tuning:
Ormosil/gold NPs
Gold nanorods
Aspect ratio dependence
Materials Development
Objectives:
1. Development/characterization of composite material with lowered
refractive index.
2. Development/characterization of composite material with enhanced
chirality.
Strategy:
1. In-situ generation of gold/silver nanoparticles to obtain a high loading
in the host material.
2. Synthesis of molecular units with high chirality and its polymeric
helical form.
3. Characterization.
4. Multiscale modeling and feedback.
Realization:
Synthesis of new chiral molecule, M-chitosan, and mixing it with
water soluble gold nanoparticles.
Material Development
S
COOH
+
Modified chitosan
Au NC
Au NC – Chitosan complex
Experimental activity: Mixing of gold NPs with
chiral template (M-chitosan, N = 10-4 M)
New bands due to gold conjugation
25
1.34mg/ml
20
Increasing concentration Au NPs
1.16mg/ml
15
CD (mdeg)
0.97mg/ml
0.76mg/ml
10
0.53mg/ml
5
0.28mg/ml
0
350
370
390
410
430
450
-5
Modified Chitosan, 1mg/ml
-10
wavelength (nm)
First observation of nanoparticle induced chirality
TEM image of the mixture
Partial aggregation is evident
Possible mechanisms of gold conjugation
Smaller particles:
Induced conformational effect helical arrangement due to
chiral template.
Larger particles:
Coating-like arrangement.
Plasmon mediated coupling
results in new band.
Check-up: Change particle morphology (nanorods), composition and size
Characterization
1. Using CD measurements to obtain chirality parameter.
2. Using Kramers-Kronig transform of reflectance spectra to obtain refractive index.
CD spectrum
Reflectance
Measured reflectance
0.1
0.05
0
400
600
800
1000
1200
Wavelength (nm)
KK transform
2
n
Chirality parameter 
obtained from CD spectrum
Lowered n
1
Complex RI
k
0
400
600
800
Wavelength (nm)
1000
1200
Modeling Multiscale Chiral Media
Quantum chemical molecular analysis and design used to predict
and optimize chiral parameter .
A. Baev et al., Optics Express 15, 5730 (2007)
Characterized Material
Chirality parameter 
from CD spectrum
Computed chirality
parameter 
Monomeric Ni Complex
(chiral organometallic complex)
Modeling NIM assisted optical power limiting (OPL)
TPA enhancement factor for a “sandwiched”
structure containing 12.5 mm of TPA material.
Baev, E. Furlani, M. Samoc, and P.N. Prasad,
Negative refractivity assisted optical power limiting,
J. Appl. Phys. 102, 043101, 2007.
Conclusion: TPA-based OPL can be enhanced
and optimized using focusing by NIM slabs.
Optical limiting curves
Modeling NIM assisted OPL
Measure Iout
PML
PML
40 m
Measure Iinp
Two-photon absorbing slab
s = 1000 GM, d = 200 m
PML
PML
40 m
Concave lense, n = 1.2, to compensate for aperture-induced focusing
TPA + NIM slab
s = 1000 GM, n = -1.4, d = 200 m
OPL performance
Modeling plasmonic nanoscale trapping
Polarization Dependent Trapping
TM analysis
TE Analysis
FSca
t
TM Trap
TE Trap
k
-|E|2
-|E|2
Plot of Fx and Fy
Plot of Fx and Fy
Use of gradient force potential
Vtrap  -|E|2 to verify 3D trapping
Modeling Scattering Optical Elements (SOE)
Example: Demultiplexer
A. Hakansson et al, Appl. Phys. Lett. 87, 193506 (2005)
1600 nm
1560 nm
Possible realization:
Dynamical patterning liquid
crystal with optical tweezers
ILPB Metamaterial Publications
and Presentations
• E. P. Furlani and A. Baev, “Electromagnetic Analysis of Cloaking Metamaterial
Structures,” Proc. COMSOL Conf. October 2008.
• E. P. Furlani and A. Baev, “Full-Wave Analysis of Nanoscale Optical Trapping,”
Proc. COMSOL Conf. October 2008.
• E. P. Furlani and A. Baev, “Free-space Excitation of Resonant Cavities Formed
from Cloaking Metamaterial,” submitted to Metamaterials, Sept 2008.
• E. P. Furlani, A. Baev and P. N. Prasad, “Optical Nanotrapping Using Illuminated
Metallic Nanostructures: Analysis and Applications,” Proc. Nanotech Conf. 2008.
• E. P. Furlani and A. Baev, “Optical Nanotrapping using Cloaking Metamaterial, first
revision under review,” Metamaterials, 2008.
• A. Baev, E. P. Furlani, P. N. Prasad, A. N. Grigorenko, and N. W. Roberts, “Laser
Nnanotrapping and Manipulation of Nanoscale Objects using Subwavelength
Apertured Plasmonic Media,” J. Appl. Phys. 103, 084316, 2008.
• A. Baev, M. Samoc, P. N. Prasad, M. Krykunov, and J. Autschbach, “A Quantum
Chemical Approach to the Design of Chiral Negative Index Materials,” Opt. Exp. 15,
9, 5730-5741, 2007.
• A. Baev, E. P. Furlani, M. Samoc, and P. N. Prasad, “Negative Refractivity assisted
Optical Power Limiting,” J. Appl. Phys. 102, 043101, 2007.