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Lighting the Way to Technology through
Innovation
ILPB Metamaterial Research

• SUNY at Buffalo
• Department of Chemistry

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Overview

• Basic Metamaterial Concepts
• ILPB Capabilities
• ILPB NIM Group
• ILPB Metamaterial Research
• Approaches to NIM fabrication
• Experimental and Experimental Results
• Publications and Presentations

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Electromagnetic Material Properties
The electromagnetic response of a material is
defined by its electromagnetic properties
permittivity ? and permeability ?
Conventional Materials
Plasmas
no transmission
Negative Index Materials
Split Rings
no transmission
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Metamaterials
Metamaterials artificially engineered materials
possessing electro-magnetic properties that do
not exist in naturally occurring materials.
Perfect Lens (Pendry, 2000)
Gunnar Dolling, et. al., Opt. Exp.14, 1842 (2006)
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ILPB Metamaterial Research/Development
Capabilities
Modeling - Design - Fabrication - Characterization
NANOPHOTONICSMaterials - DevicesSystems
PLASMONICS NanoparticlesNanostructure Media
Metamaterials NIM ApplicationsNovel Photonic
Devices
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Characterization Facilities
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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

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ILPB Metamaterials Research
ILPB is pursuing a bottom-up approach to NIM
fabrication
Bottom-up approach Chiral NIM Media(Chemical
Synthesis/Assembly)
Top-down approach Resonant Metallic
Nanostructures(Lithography)
Chiral molecules doped with plasmonic
nanoinclusions
Achieves e lt 0, m lt 0 from EM coupling between
paired plasmonic elements
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Chiral Media Development
Theoretical modeling Preliminary quantum
chemical and EM modeling predicts enhanced
chirality and lowered permittivity
Selected model structures Helical polyacetylenes
Plasmonic nanoparticles attached to chiral
components lower dielectric permittivity
Proposed synthetic route to chiral components
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Basic Chiral Media Relations
Current Status of Chiral Media Properties
Dnplasmonic 0.5 kcomposite 10-2
Target Properties for next year Dnplasmonic 1
kcomposite 5 x 10-1
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Materials Development

• Objectives
• Development/characterization of composite
  material with lowered refractive index.
• Development/characterization of composite
  material with enhanced chirality.
• Strategy
• In-situ generation of gold/silver nanoparticles
  to obtain a high load in the host material.
• Synthesis of molecular units with high chirality
  and its polymeric helical form.
• Characterization.
• Multiscale modeling and feedback.
• Realization
• The use of photochemical decomposition of noble
  metal precursors to generate plasmonic particles
  loaded composites.

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PVP host doped with silver nanoparticles.
Suppression of the refractive index on the high
energy side of plasmonic resonance.
Dn 0.5
Dn
l 337 nm
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Approaches planned for enhancing the load

• Higher load of NPs may be possible with
• Using direct mixing in the organic phase.
  Example PMMA host doped with gold nanoparticles
  prepared in chlorobenzene.
• Using templates with high density of binding
  sites.
• In-situ generation by two-photon lithography.
• Using nanoparticles of different morphology
• Nanorods.
• Multipods.
• Core-shell structures.

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TEM image of gold nanorods
TEM image of gold nanoshell
Plasmonic band tuning Ormosil/gold NPs
Gold nanorods
Aspect ratio dependence
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Materials Development

• Objectives
• Development/characterization of composite
  material with lowered refractive index.
• Development/characterization of composite
  material with enhanced chirality.
• Strategy
• In-situ generation of gold/silver nanoparticles
  to obtain a high loading in the host material.
• Synthesis of molecular units with high chirality
  and its polymeric helical form.
• Characterization.
• Multiscale modeling and feedback.
• Realization
• Synthesis of new chiral molecule, M-chitosan, and
  mixing it with
• water soluble gold nanoparticles.

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Material Development
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Experimental activity Mixing of gold NPs with
chiral template (M-chitosan, N 10-4 M)
New bands due to gold conjugation
1.34mg/ml
Increasing concentration Au NPs
1.16mg/ml
0.97mg/ml
0.76mg/ml
0.53mg/ml
0.28mg/ml
Modified Chitosan, 1mg/ml
First observation of nanoparticle induced
chirality
TEM image of the mixture Partial aggregation is
evident
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Possible mechanisms of gold conjugation
Larger particles Coating-like arrangement. Plasmo
n mediated coupling results in new band.
Smaller particles Induced conformational effect
- helical arrangement due to chiral template.
Check-up Change particle morphology (nanorods),
composition and size
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Characterization

1. Using CD measurements to obtain chirality
   parameter.
2. Using Kramers-Kronig transform of reflectance
   spectra to obtain refractive index.

Measured reflectance
CD spectrum
KK transform
Lowered n
Chirality parameter ? obtained from CD spectrum
Complex RI
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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
Monomeric Ni Complex(chiral organometallic
complex)
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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.
Optical limiting curves
Conclusion TPA-based OPL can be enhanced and
optimized using focusing by NIM slabs.
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Modeling NIM assisted OPL
Two-photon absorbing slab s 1000 GM, d 200 mm
Measure Iout
Measure Iinp
PML
PML
Concave lense, n 1.2, to compensate for
aperture-induced focusing
PML
PML
TPA NIM slab s 1000 GM, n -1.4, d 200 mm
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OPL performance
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Modeling plasmonic nanoscale trapping
Polarization Dependent Trapping
TM analysis
TE Analysis
FScat
TE Trap
TM Trap
k
-E2
-E2
Plot of Fx and Fy
Plot of Fx and Fy
Use of gradient force potential Vtrap ? -E2 to
verify 3D trapping
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Modeling Scattering Optical Elements (SOE)
Possible realization Dynamical patterning liquid
crystal with optical tweezers
Example Demultiplexer A. Hakansson et al, Appl.
Phys. Lett. 87, 193506 (2005)
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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.