“Lighting the Way to Technology through Innovation”

1. www.photonics.buffalo.edu ILPB Metamaterial Research “Lighting the Way to Technology through Innovation” SUNY at Buffalo Department of Chemistry

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

3. 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

4. n > 0 n < 0 Light focusing Light deflection NIM water*  = -1.3,  = -1.3 Normal water  = 1.7,  = 1 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)

5. ILPB Metamaterial Research/Development Capabilities Modeling - Design - Fabrication - Characterization NANOPHOTONICSMaterials - DevicesSystems PLASMONICSNanoparticlesNanostructure Media Metamaterials NIM ApplicationsNovel Photonic Devices

6. Macroscopic Scale • CD spectroscopy • Interferometry • Reflectometry Characterization Facilities

7. 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 • ResearcherWon Jin Kim – Polymer Chemistry, Material Synthesis • Researcher Shobha Shukla - Lithography for Nanostructured Media

8. 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 < 0, m < 0 from EM coupling between paired plasmonic elements

9. 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

10. Basic Chiral Media Relations Current Status of Chiral Media Properties Dnplasmonic = 0.5 kcomposite = 10-2 Target Properties for next year Dnplasmonic ~ 1kcomposite ~ 5 x 10-1

11. 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.

12. 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

13. 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.

14. TEM image of gold nanorods TEM image of gold nanoshell Plasmonic band tuning: Ormosil/gold NPs Gold nanorods Aspect ratio dependence

15. 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.

16. Material Development

17. 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

18. Possible mechanisms of gold conjugation Larger particles: Coating-like arrangement. Plasmon 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

19. Characterization • Using CD measurements to obtain chirality parameter. • 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

20. Modeling Multiscale Chiral Media Chirality parameter  from CD spectrum Computed chiralityparameter  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)

21. 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.

22. 40 mm 40 mm 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

23. OPL performance

24. Modeling plasmonic nanoscale trapping Polarization Dependent Trapping TM analysis TE Analysis FScat TE Trap TM 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

25. 1560 nm 1600 nm 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)

26. 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.