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Full Spatio-Temporal Coherent Control on Nanoscale (NSF NIRT Grant CHE-0507147) Mark 1 Stockman , Keith 2 Nelson , and Hrvoje 3 Petek 1Department of Physics and Astronomy, Georgia State University; 2Department of Chemistry, MIT; 3Department of Physics and Astronomy, University of Pittsburgh Nanoconcentration of Terahertz Radiation in Plasmonic Waveguides Motivation and Goals Optical processes on the nanoscale are of great importance both fundamentally and for applications in science, engineering, technology, and defense. Among the fundamental problems of the nanoscale optics and nanoplasmonics is delivery of the optical fields to the nanoscale and their control with nanoscale precision. The conventional methods with tapered optical fibers and sharp metal tips can produce high enough enhancements of the local optical field by the price of a very efficiency of the energy transfer. A goal of this project is to find much more efficient ways to transfer energy to the nanoscale using tapered nanoplasmonic structures. The concentration of the optical energy in the nanoplasmonic structures is coherently controlled using spatio-temporal pulse shapers. We establish the principal limits for the nanoconcentration of the THz radiation in metal/dielectric waveguides and determine their optimum shapes required for this nanoconcentration. We predict that the adiabatic compression of THz radiation from the initial spot size of R0∼λ0 to the final size of R = 100− 250 nm can be achieved, while the THz radiation intensity is increased by a factor of ×10 to ×250. Near a metal nanoparticle carriers exchange a surface plasmon quantum, which can be represented as a modification of Coulomb interaction between carriers. We obtain renormalized interaction near an arbitrary metal nanostructure Interaction near Metal-Dielectric Nanoshell Terahertz wave in dielectric slab covered with metal Thick slab Thin slab k0 c Control of surface plasmons with phase-correlated femtosecond light fields sn n (r ) *n (r) 1 4 W (r, r; ) h r r h n s() sn Properties of Plasmonic-Renormalized Interaction The physical process that limits the extent of spatial concentration is the skin effect, i.e., penetration of the radiation into the metal that causes the losses: the THz field penetrates the depth of ls = 30−60 nm of the metal, which determines the ultimum localization radius. PEEM Imaging of Surface Plasmon Polaritons Simulation Nanoplasmonic Renormalization of Coulomb Interactions Experiment Interferometric time-resolved photoemission electron microscopy ITR-PEEM image: 10-fs, single pulse (i) It is long-ranged Eigenmodes are composed of “hot spots” separated by distances on the scale of the entire plasmonic nanostructure Re m () Q ~ () Im m () Q~100-150 in near-IR for silver (iii) It affects a wide range of many-body phenomena near metal nanostructures: (a) scattering between charge carriers, the carriers and ions, (b) ion-ion interactions, (c) exciton formation (d) chemical reactions and catalysis Adiabatic Concentration of Terahertz Energy in Graded Waveguides Spectroscopic Microscopy by means of Time-of-flight-PEEM (ii) It is highly resonant. Near resonance s(ω)=sn, W is increased by quality factor Q Plasmonic-Renormalized Energy Transfer Förster rate near metal nanostructure 2 2 2 J 2 d d d a F W (r, r; ) 9 Dyadic Green’s function 2 W (r, r; ) W (r, r; ) r r J is spectral overlap integral Time-of-flight PEEM: Dx~70 nm, DE~100 meV Energy Transfer near Metal-Dielectric Nanoshells Control of SPPs in nano-optics is available by using phase-correlated fs-optical pulses. (1) FRET across nanoshell Fields in tapered silver wedge cavity, 1 THz The SPP and light interferes on the screen Light – SPP Coupling Interference control γF Fields in tapered silver coaxial cable, 1 THz Re m () Q~ Im m () Adiabatic Nanoconcentration of Terahertz Energy in Funnel Waveguides To provide for the optimum guiding of the THz wave and its concentration on the nanoscale, the terminating (nanoscopic) part of the waveguide should be tapered in a funnel-like manner. Q~100-150 in near-IR Off-centered focusing of SPP by Circular-arc lenses (2) FRET averaged over acceptor position γF d Competing processes: (3) Energy transfer to the metal γm (4) Radiation γr Although near thick nanoshells FRET quantum efficiency is small, FRET in the vicinity of the nanoshells with high aspect ratios has quantum efficiency around 50% Fields in curved silver wedge cavity, 1 THz 1. 2. 3. 4. 5. Interference pattern reversal is achieved by SPP excitation with different phase-correlated pulse pairs 6. 7. In-phase pair of pulses Out-of-phase pair of pulses 8. Fields in curved silver coaxial cable, 1 THz M. I. Stockman, in Plasmonic Nanoguides and Circuits, edited by S. I. Bozhevolny, Adiabatic Concentration and Coherent Control in Nanoplasmonic Waveguides (World Scientific Publishing, Singapore, 2008). M. I. Stockman, Attosecond Physics - an Easier Route to High Harmony, Nature 453, 731-733 (2008). M. I. Stockman, Spasers Explained, Nature Photonics 2, 327-329 (2008). M. I. Stockman, Ultrafast Nanoplasmonics under Coherent Control, New J. Phys. 10 025031-1-20 (2008). A. Rusina, M. Durach, K. A. Nelson, and M. I. Stockman, Nanoconcentration of Terahertz Radiation in Plasmonic Waveguides, Opt. Expr. 16, 18576-18589 (2008). K. F. MacDonald, Z. L. Samson, M. I. Stockman, and N. I. Zheludev, Ultrafast Active Plasmonics: Transmission and Control of Femtosecond Plasmon Signals, arXiv:0807.2542 (2008). X. Li and M. I. Stockman, Highly Efficient Spatiotemporal Coherent Control in Nanoplasmonics on a Nanometer-Femtosecond Scale by Time Reversal, Phys. Rev. B 77, 195109-1-10 (2008). D. K. Gramotnev, M. W. Vogel, and M. I. Stockman, Optimized Nonadiabatic Nanofocusing of Plasmons by Tapered Metal Rods, J. Appl. Phys. 104, 034311-1-8 (2008). 9. 10. 11. 12. 13. 14. M. Durach, A. Rusina, V. I. Klimov, and M. I. Stockman, Nanoplasmonic Renormalization and Enhancement of Coulomb Interactions, New J. Phys. 10, 105011-1-14 (2008). J. Dai, F. Cajko, I. Tsukerman, and M. I. Stockman, Electrodynamic Effects in Plasmonic Nanolenses, Phys. Rev. B 77, 115419-1-5 (2008). M. I. Stockman, M. F. Kling, U. Kleineberg, and F. Krausz, Attosecond Nanoplasmonic Field Microscope, Nature Photonics 1, 539-544 (2007). A. Kubo and H. Petek, Femtosecond Time-resolved Photoemission Electron Microscope Studies of Surface Plasmon Dynamics, J. Vac. Soc. Jap. 51, 368 (2008) (in Japanese). H. Petek and A. Kubo, Ultrafast photoemission electron microscopy: imaging light with electrons on the femto-nano scale, in Ultrafast Phenomena XVI. E. Riedle and R. Schoenlein, Springer-Verlag, Berlin (in press; invited). M. Durach, A. Rusina, M. I. Stockman, and K. Nelson, Toward Full Spatiotemporal Control on the Nanoscale, Nano Lett. 7, 3145-3149 (2007).