Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Support: Nanoplasmonics: Optical Properties of Plasmonic Nanosystems Mark I. Stockman Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA Lecture 1: Introduction to Nanoplasmonics. Plasmon Polaritonics: Propagation of Surface Plasmon Polaritons in Nanostructured Systems Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.1 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Meet the Author in his natural environment: Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.2 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 CONTENTS OF THE COURSE • Lecture 1: Introduction to Nanoplasmonics. Plasmon Polaritonics: Propagation of Surface Plasmon Polaritons in Nanostructured Systems •Lecture 2: Nanoplasmonics of Nanosystems: Localized Surface Plasmon Resonances •Lecture 3: Ultrafast, Nonlinear, and Quantum Nanoplasmonics Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.3 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 LECTURE 1 Introduction to Nanoplasmonics. Plasmon Polaritonics: Propagation of Surface Plasmon Polaritons in Nanostructured Systems 1. Introduction Problem of nanolocalization of energy Surface plasmons and enhanced optical fields Applications of surface plasmonics 2. Surface plasmon polaritons as interface electromagnetic waves Maxwell equations solution for metal-dielectric interface Surface plasmon polaritons in layered media 3. Adiabatic energy concentration in tapered plasmonic waveguides: theory and experiment 4. Negative refraction in nanoplasmonic waveguides (optional) Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.4 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 PROBLEMS IN NANOOPTICS Macro- and Microscale Delivery of energy to nanoscale: Conversion of propagating EM wave to local fields Lecture Course Nanoplasmonics 2015 Enhancement and control of local nanoscale fields. Enhanced nearfield responses http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Ultrafast, nonlinear, and quantum nanoplasmonics (SPASER) Lecture 1 p.5 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Concentration of optical (electromagnetic wave) energy: Minimum extension of electromagnetic wave in uniform space Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.6 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Nanoplasmonics in a nano-nutshell Wavelength, ~1000 nm Enhanced Local Fields in Proximity of Metal Nanoparticle are Nanoscale-Localized Mean free path, ~40 nm Skin depth, ~25 nm Nanoplasmonics: ~10 nm vF ω Spatial dispersion/Nonlocality radius, ~1 nm Field enhancement Polarizability: or Quality factor: 3 εm − εd α= R , ε m = −2ε d − Re ε m ε m + 2ε d Q= ~ 10 − 100 Im ε m Localized Surface Plasmon: Lattice Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Electrons Lecture 1 p.7 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 I. Freestone, N. Meeks, M. Sax, and C. Higgitt, The Lycurgus Cup - a Roman Nanotechnology, Gold Bull. 40, 270-277 (2007) © Trustees of British Museum Nanoplasmonic colors are very bright. Scattering and absorption of light by them are very strong. This is due to the fact that all of the millions of electrons move in unison in plasmonic oscillations Nanoplasmonic colors are also eternal: metal nanoparticles are stable in glass: they do not bleach and do not blink. Gold is stable under biological conditions and is not toxic in vivo Scanning electron microscopy Dark field optical microscopy W. A. Murray and W. L. Barnes, Plasmonic Materials, Adv. Mater. 19, 3771-3782 (2007) [Scale bar: 300 nm] C. Orendorff, T. Sau, and C. Murphy, ShapeDependent …, Small 2, 636-639 (2006) Lecture Course Nanoplasmonics http://www.phy-astr.gsu.edu/stockman 2015 E-mail: mstockman@gsu.edu Lecture 1 p.8 7/12/2015 11:31 AM Eternal nanoplasmonic (Notre Dame de Paris) Department of Physics colors and Astronomy Georgia State University Atlanta, GA 30303-3083 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.9 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Lecture Course Nanoplasmonics http://www.phy-astr.gsu.edu/stockman Lecture 1 p.10 The most beautiful colors of the world: La Sainte 7/12/2015 Chapelle, Paris 2015 polychroic nanoplasmonic E-mail: mstockman@gsu.edu 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 REUBEN Lecture Course Nanoplasmonics 2015 ASHER http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu DAN Lecture 1 p.11 7/12/2015 11:31 AM Department of Physics and Astronomy Plasmonic Hot Spots Georgia State University Happy 20th Anniversary! Atlanta, GA 30303-3083 •D. P. Tsai et al., Phys. Rev. Lett. 72, 4149 (1994) •M. I. Stockman et al., Phys. Rev. Lett. 75, 2450 (1995) •M. I. Stockman, L. N. Pandey, and T. F. George, Phys. Rev. B 53, 2183-2186 (1996) L. Novotny and S. J. Stranick, Annual Rev. Phys. Chem. 57, 303-331 (2006) M. Rang et al., Nano Lett. 8, 3357 (2008) •J. A. Fan et al., Science 328, 1135 (2010) •M. Hentschel et al., Nano Lett. 10, 2721 (2010) Lecture Course Nanoplasmonics 2015 K. Li, M. I. Stockman, and D. J. Bergman, Phys. Rev. Lett. 91, 227402 (2003) http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu M. I. Stockman, Phys. Rev. Lett. 93, 137404 (2004) Lecture 1 p.12 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 A. Kubo, K. Onda, H. Petek, Z. Sun, Y. S. Jung, and H. K. Kim, Femtosecond Imaging of Surface Plasmon Dynamics in a Nanostructured Silver Film, Nano Lett. 5, 1123 PEEM Image as a Function of Delay (250 as per frame) (2005). 200 nm 30 femtoseconds from life of a nanoplasmonic systems Localized SP hot spots are deeply subwavelength as seen in PEEM (photoemission electron microscope) 1 Delay 0.5 -100 -50 50 100 150 200 -0.5 -1 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.13 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Applications of Nanoplasmonics: 1. 2. 3. 4. 5. 6. 7. Ultrasensitive and express sensing and detection using both SPPs and SPs (LSPRs): see,e.g., J. N. Anker, W. P. Hall, O. Lyandres, N. C. Shah, J. Zhao, and R. P. Van Duyne, Biosensing with Plasmonic Nanosensors, Nature Materials 7, 442-453 (2008); NSOM (SNOM) Nanoantennas: Coupling of light to nanosystems. Extraction of light from LEDs and lasers [N. F. Yu, J. Fan, Q. J. Wang, C. Pflugl, L. Diehl, T. Edamura, M. Yamanishi, H. Kan, and F. Capasso, SmallDivergence Semiconductor Lasers by Plasmonic Collimation, Nat. Phot. 2, 564-570 (2008)]; nanostructured antennas for photodetectors and solar cells; heat-assisted magnetic memory [W. A. Challener et al., Nat. Photon. 3, 220 (2009)] Photo- and chemically stable labels and probes for biomedical research and medicine Nanoplasmonic-based immunoassays and tests. Home pregnancy test (dominating the market), PSA test (clinic), troponin heart-attack test, and HIV tests (in trials) Near perspective: Generation of EUV and XUV pulses Thermal cancer therapy: L. R. Hirsch, R. J. Stafford, J. A. Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J. Halas, and J. L. West, Nanoshell-Mediated Near-Infrared Thermal Therapy of Tumors under Magnetic Resonance Guidance, Proc. Natl. Acad. Sci. USA 100, 13549-13554 (2003). C. Loo, A. Lowery, N. Halas, J. West, and R. Drezek, Immunotargeted Nanoshells for Integrated Cancer Imaging and Therapy, Nano Lett. 5, 709-711 (2005) Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.14 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Surface plasmon frequency shifts to red upon molecules adhesion Molecule ω0 p ωp = εd Nanosensors based on enhanced local fields •X. Zhang, M. A. Young, O. Lyandres, and R. P. Van Duyne, Rapid Detection of an Anthrax Biomarker by Surface-Enhanced Raman Spectroscopy, Journal of American Chemical Society 127, 4484 (2005). •C. R. Yonzon, C. L. Haynes, X. Y. Zhang, J. T. Walsh, and R. P. Van Duyne, A Glucose Biosensor Based on Surface-Enhanced Raman Scattering, Anal. Chem. 76, 78-85 (2004). Metal Nanoparticle Lecture Course Nanoplasmonics 2015 Raman radiation (SERS), fluorescence, quenching, … http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.15 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Use of Enhanced Local Fields for Nano-Microscopy Metal tip Nanoparticle Enhanced Local Optical Fields Scattered Light, SERS Lecture Course Nanoplasmonics 2015 •L. Novotny and S. J. Stranick, NearField Optical Microscopy and Spectroscopy with Pointed Probes, Annual Rev. Phys. Chem. 57, 303-331 (2006). •A. Hartschuh, E. J. Sanchez, X. S. Xie, and L. Novotny, High-Resolution NearField Raman Microscopy of Single-Walled Carbon Nanotubes, Phys. Rev. Lett. 90, 095503 -1-4 (2003). Nanoscale http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.16 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 NSOM images of healthy human dermal fibroblasts in liquid obtained in transmission mode with a Nanonics cantilevered tip with a gold nanosphere Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.17 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.18 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Chirality Changes in Carbon Nanotubes Studied with Near-Field Raman Spectroscopy Neil Anderson, Achim Hartschuh, and Lukas Novotny Nano Lett. 577 – 582 (2007); DOI: 10.1021/nl0622496 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.19 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Next generation of scanning near-field optical microscopy (SNOM) with chemical mapping: Adiabatic concentration of optical energy and giant surface-enhanced Raman scattering (SERS); resolution 7 nm.s (to be discussed in the course) Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.20 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.21 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.22 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 SP Sensing and Detection 1 – Antigen (hCG) 2 – Primary antibody 3 – Gold nanosphere functionalized with secondary antibody 1 – Substrate 2 – Gold nanofilm 3 – Latex nanospheres 4 – Gold nanolayer 5 – Antibodies 6 - Analyte molecules Adapted from: T. Endo et al., Anal. Chem. 78, 6465 (2006). J.N. Anker et al. , Nature Materials 7, 442 (2008) Lecture Course Nanoplasmonics 2015 N. Liu et al., Nat. Mater. advance online publication DOI: 10.1038/nmat3029 (2011) http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.23 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 M. I. Stockman, Nanoplasmonic Sensing and Detection, Science 348, 287-288 (2015). Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.24 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.25 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 William L. Barnes, Alain Dereux & Thomas W. Ebbesen, Nature 424, 824 (2003) Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.26 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 SURFACE PLASMON POLARITONS Assume that we have a plane interface and consider propagation in the xy plane. z y x Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.27 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Maxwell Equations in the absence of the external currents and charges: for E, H ∝ exp(-iωt ) 1 ∂B ∇×E = − c ∂t 1 ∂D ∇×H = c ∂t ∇D = 0 , ⇒ ⇒ ∇ × E = ik0 µH ∇ × H = −ik0εE, where k0 ≡ ω c e ∇H = 0 ; F = eE + [ v × B] Lorent z formuala c See, e.g., L. D. Landau and E. M. Lifshitz, Electrodynamics of Continuous Media (Pergamon, Oxford and New York, 1984). Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.28 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 ∞ General type of linear response D(r, t ) = ∫ ε (r − r′, t − t ′)E(r′, t ′) dt ′d 3 r ′ −∞ ∞ B(r, t ) = 3 ′ ′ ′ ′ ′ ( , ) ( , ) − − µ r r t t H r t d t d r′ ∫ −∞ ∞ Local response D(r, t ) = ∫ ε (r, t − t ′)E(r, t ′)dt ′ ⇒ D(ω ) = ε (ω )E (ω ) −∞ ∞ B(r , t ) = ∫ µ (r, t − t′)H(r, t′)dt′ ⇒ B(ω ) = µ (ω )H (ω ) −∞ ∞ ∞ D(ω ) = ∫ D(t )e dt , D(t ) = ∫ D(ω )e −iωt iωt -∞ Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu -∞ dω , 2π Lecture 1 p.29 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Relation between permittivity and conductivity (Optional) ∂ρ (t ) ∂j(t ) Continuity eq. : + =0 ⇒ ∂t ∂r ∂P ∂ P( t ) ρ =⇒ j(t ) = ⇒ j(ω ) = −iωP(ω ) ∂r ∂t ε (ω ) − 1 D(ω ) = E(ω ) + 4πP(ω ) = ε (ω )E(ω ) ⇒ P(ω ) = E(ω ) 4π ε (ω ) − 1 j(ω ) = −iω E(ω ) 4π ε (ω ) − 1 ⇒ σ (ω ) = −iω j(ω ) = σ (ω )E(ω ) 4π 4π ε (ω ) = 1 + i σ (ω ) ω Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.30 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Seeking for solution as a TM wave H = (H x ( y, z , t ),0,0 ) E = (0, E y ( y, z , t ), E z ( y, z , t ) ) (To be confirmed by equations) Spatio-temporal dependence: H x ( y, z , t ) = H x ( z ) exp(iky − iωt ) Ei ( y, z , t ) = Ei ( z ) exp(iky − iωt ) , i = y, z Wave equations are obtained by Maxwell equations: ∇ 2 + k02εµ H = 0 ⇒ ( (∇ ) 2 ) + k02εµ E = 0 Lecture Course Nanoplasmonics 2015 ⇒ applying curl operation to ∂2 2 2 2 − k + k0 εµ H x = 0 ∂z ∂2 2 2 2 − k + k0 εµ E y , z = 0 ∂z http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.31 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Seeking H x ( z ) ∝ exp(±κz ), E y , z ( z ) ∝ exp(±κz ) From the wave equations: k02εµ = k 2 − κ 2 , k0 = ω ; c ∇ × H = −ik0εE ⇒ x: y: z: ∂H z ∂H y − = −ik0εE x ⇒ E x = 0 ∂y ∂z ∂H x ∂H z iκ Hx = −ik0εE y ⇒ E y = ± − k 0ε ∂z ∂x ∂H y ∂H x k Hx − = −ik0εE z ⇒ E z = k 0ε ∂x ∂y Because we have already satisfied the wave equations, the second Maxwell equation is the satisfied identically Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.32 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Boundary conditions are continuity across the interface plane of i ∂H x H x and E y = k0ε ∂z For a planar layered medium, surface plasmon polariton (SPP) is a TM wave where in an i-th medium layer at a point (y, z) for a wave propagating in the y direction H x (i, y, z ) = [Ai exp(κ i z ) + Bi exp(−κ i z )]exp(iky ), iκ i [Ai exp(κ i z ) − Bi exp(−κ i z )]exp(iky), E y (i, y, z ) = ε i k0 E z (i, y, z ) = k εi H x (i, y, z ); k ≡ k y ; k εµ = k − κ , k0 = 2 0 Lecture Course Nanoplasmonics 2015 2 2 ω c ; i = 1,2,... is layer number http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.33 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 For metal/dielectric interface Boundary conditions : H x (1, y, z ) = H x (2, y, z ) E y (1, y, z ) = E y (2, y, z ) κ1 κ2 =− ε1 ε2 E y (1, y, z ) = − iκ 1 B1 exp(−κ i z ) exp(iky ), ε 1k 0 y These conditions reduce to : B1 = A2 z H (1, y , z ) = B exp(−κ z ) exp(iky ), 1 1 x x Lecture Course Nanoplasmonics 2015 H x (2, y, z ) = A2 exp(κ 2 z ) exp(iky ), iκ 2 E y (2, y, z ) = A2 exp(κ 2 z ) exp(iky ). ε 2 k0 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.34 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Boundary conditions : κ1 κ2 =− ε1 ε2 Wave equations : k ε = k −κ 2 0 1 2 2 1 Definition : k0 = ω c k02ε 2 = k 2 − κ 22 Transforming : Substituti ng : ⇓ κ12 κ 22 = 2 2 ε1 ε 2 k02ε 1 − k 2 ⇒ ε = k02ε 2 − k 2 ε 22 εε Algebraically solving for k 2 : k 2 = k02 1 2 ε1 + ε 2 2 1 ε 22 ε 12 2 2 Finding by substituti on : κ = − k , κ 2 = − k0 . ε1 + ε 2 ε1 + ε 2 2 1 Lecture Course Nanoplasmonics 2015 2 0 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.35 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Metal-Dielectric Interface For a two-medium system, the SPP wave vector is found as a function of frequency (dispersion relation): k= ω c ε 1ε 2 ε1 + ε 2 Evanescent decay exponents in these two media are found as ω ε 12 κ 1= − ε1 + ε 2 c ω ε 22 κ 2= − c ε1 + ε 2 From these, it follows that for the existence of SPPs, it is necessary and sufficient that ε 1 + ε 2 < 0 and ε 1ε 2 < 0 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.36 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Dielectric permittivity for silver and gold in optical region P. B. Johnson and R. W. Christy, "Optical-Constants of NobleMetals," Physical Review B 6, 4370-4379 (1972). 1.24 λ[µ ] = ω[eV] Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.37 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 ω p2 ε = ε0 − ω (ω + iγ ) Drude formula: Im ε ; γ = 0.02 eV 0 20 40 60 80 100 Im ε ; γ = 0.055 eV 8 1 2 3 4 5 Re ε ; ε 0 = 3.6; ω p = 9.1 eV 6 6 4 4 2 2 1 2 3 4 5 ω (eV) Fit to near-ir Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu 1 2 3 4 ω (eV) Fit to visible Lecture 1 p.38 7/12/2015 11:31 AM 5 Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Surface plasmon dispersion and resonance for real silver [data of Johnson and Christy, P. B. Johnson and R. W. Christy, OpticalConstants of Noble-Metals, Phys. Rev. B 6, 4370-4379 (1972)] ω (eV) ε = 1 2 3.5 3 2.5 2 1.5 1 0.5 Re[ε m + ε d ] = 0 ε2 = 3 ω ε mε d k= c εm + εd 20000 40000 60000 80000 Lecture Course Nanoplasmonics 2015 Rek (cm -1 ) [Inverse wavelength in cm] http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.39 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Surface Plasmon Polaritons and Sommerfeld-Zenneck Waves (example for silver in vacuum) k= ω (eV) 6 ω c ε m (ω ) ε m (ω ) + 1 κ vacuum = ε m (ω ) + 1 Light line 6 Zenneck wave 4 c − 1 ω (eV) Light line 5 ω 5 4 3 Overdamped SPP 2 1 Propagating SPP 3 2 10000 20000 30000 40000 50000 10000 20000 -1 Rek (cm ) Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu 30000 40000 50000 Imk (cm-1 ) Lecture 1 p.40 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Surface plasmon polariton fields Metal Metal y Lecture Course Nanoplasmonics 2015 y http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.41 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Surface plasmon polaritons fields Metal Metal y Lecture Course Nanoplasmonics 2015 y http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.42 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Topography of Surface Plasmon Polariton Electric Fields Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.43 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 SPP excitation in Kretschmann geometry and SPP sensing Sensors: http://www.biacore.com/ ε1 sin θ K = ε1 > ε mε 2 , where θ K is Kretschmann angle εm + ε2 ε mε 2 > ε2 εm + ε2 ε1 sin θTIR = ε 2 , where θTIR is total internal reflection angle θ K > θTIR Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.44 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Three-Layer Systems Dispersion relation (exact analytical expression), where d is the layer thickness: defines the SPP wave vector k u1 − u2 ) × ( u3 − u2 ) ( exp [ 2k0d ε 2u2 ] = ; ( u1 + u2 ) × ( u3 + u2 ) ui = 1 ω k2 ε ; − = k i 0 k02 c εi Here ε i is dielectric permittivity of i -th layer Another form: u2 (u1 + u3 ) tanh[k0 dε 2u2 ] = − u1u3 + u22 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.45 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Problem Find quasistatic limit of the dispersion relation, which describes thin metal nanofilms and graphene embedded between two dielectrics. Obtain 2 2 an explicit solution by applying the Drude formula ε 2 = −ω p / ω . Finally, express through Fermi energy EF of electrons (assuming a very low temperature kBT<< EF ). Hint: Consider limit k k0 ε i while kd → 0 u2 ( u1 + u3 ) 1 k2 ω tanh [ k0d ε 2u2 ] = ; ui =2 − ε i ; k0 = − 2 ε i k0 u1u3 + u2 c Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.46 7/12/2015 11:31 AM Solution to Problem Department of Physics and Astronomy Georgia State University 2 Atlanta, GA 30303-3083 2 1 3 i 0 2 2 2 2 i 1 3 2 0 u (u + u ) ω 1 k tanh [ k d ε u ] = ; u = − ε i ; k0 = − ε k uu +u c ε1 + ε 3 1k 1 k − →0 ; tanh k0d ε 2 ui ε i k0 ε 2 k0 ε2 Thus tanh can be expanded as tanh x x yielding ε1 + ε 3 . k− d ε 2 (ω ) Substituting ε 2 = −ω / ω , we obtain SPP dispersion relation: 2 p 2 ω ε1 + ε 3 kd , or ω =ω p k 2 ωp d ε1 + ε 3 2 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.47 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 ω 2 m ε1 + ε 3 4π ne 2 = For 3D metal, ω p = , thus k . 2 m 4π ne d Substituting relation between density and Fermi energy EF , n mEF 2 2 ε1 + ε 3 , we obtain k ω , or = 2 2 4e E F π d ε1 + ε 3 k ω (ω + iγ ) 2 with collision rate γ . 4e E F For graphene in terms of EF , the SPP dispersion relation can be shown to be exactly the same. 2 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.48 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 IMI Waveguide Fast SPP root (Long range SPP) Slow SPP root (Short range SPP) Two roots for nano-thin silver in vacuum: Symmetric and Antisymmetric SPPs. No cut-off for SPP as thickness tends to zero Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.49 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Dispersion Relations for Symmetric Systems ε1 = ε 3 2u1u2 2 tanh x − 2 tanh [ k0d ε 2u2 ] = ; using: tanh 2 x = 2 1 + tanh 2 x u1 + u2 Parity (symmetry) is conventionally defined as that of the normal (z) component of the electric field or the magnetic field (x-component) Even (symmetric) mode u1 1 tanh k0 dε 2u2 = − u2 2 Lecture Course Nanoplasmonics 2015 Odd (antisymmetric) mode u2 1 tanh k0 dε 2u2 = − u1 2 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.50 7/12/2015 11:31 AM of Physics and of Astronomy Dispersion Department relations for nanofilm silver in vacuum (IMI structure): Georgia State University SymmetricAtlanta, mode GA (dashed) and antisymmetric mode (solid line) 30303-3083 Negative refraction branch ∂ω vg = <0 ∂k Decay exponent (Imk) for 30 nm silver layer Symmetric mode Lecture Course Nanoplasmonics 2015 Antisymmetric mode http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.51 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Local electric fields for 10 nm silver layer in vacuum at 2.2 eV frequency Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.52 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Local fields for 10 nm layer of silver in vacuum for a high wave vector Rek=5 105 cm-1 Antisymmetric mode: positive refraction Symmetric mode: negative refraction, high loss (practically, no propagation). The sign of refraction is determined by the sign of the group velocity v g = ∂ω ∂k Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.53 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 SPPs in Metal-Insulator-Metal Waveguides ε m (ω) εd a ε m (ω) for odd (antisymmetric) mode: for all modes: Lecture Course Nanoplasmonics 2015 Im ko ⋅ Re ko < 0 Re ko ≤ Im ko http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu negative refraction large dissipation Lecture 1 p.54 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Radiative condition (other “causality”): Selecting one of the two solutions in electrodynamics. Mandelstam-Veselago’s negative refraction v pvg > 0 v pvg < 0 k k k || k ∂ω kω vg = ; vp = k ∂k k k k || k′ k′ Universal negative refraction condition from causality : Im k ⋅ Re k < 0 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.55 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.56 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 General condition of negative refraction in isotropic medium (does not depend on choice of the square root sign for n): 2 Im n < 0 or Im n ⋅ Re n < 0 or Im k ⋅ Re k < 0; Im n 2 ≡ Re ε Im µ + Re µ Im ε . Group velocity is the transfer of energy velocity only if loses are small enough. If losses at the observation frequency are zero, then an exact causality relation is valid for isotropic medium without spatial dispersion: ∞ c2 2 Im n 2 (ω1 ) = 1+ ∫ dω1 , where ω is the observation frequency 2 2 2 π 0 ω1 − ω v pvg ( ) Criterion of negative refraction without loss at the observation frequency is ∞ Im n 2 (ω1 ) ∫ (ω 0 Lecture Course Nanoplasmonics 2015 2 1 −ω ) 2 2 dω1 < - π 2 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.57 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.58 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 CONCLUSIONS 1. In metal/dielectric layered systems there exist surface plasmon polariton (SPP) modes of different symmetries 2. For a metal layer in a dielectric medium, there are two types of SPP: symmetric (fast or long-range) SPP and antisymmetric (slow or short-range) SPP 3. Slow SPP for a thin metal film is nanolocalized at the surface of the film. It is useful to couple nanosystems to laser sources. 4. There is no cut-off as SPP wavelength tends to infinity. 5. Losses of negative refraction (back-propagating SPP) are very large 6. To have negative refraction without loss at an observation frequency, there must be loss in the adjacent region of negative refraction Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.59 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Adiabatic Nano-Optics Conventional (non-adiabatic) conversion to the near zone (direct excitation of local, near-zone fields by far-zone radiation) is very energy-inefficient, though can generate high local fields. Both aperture and aperturless methods lead to loss of the major fraction of energy. If one could focus optical radiation from the far zone to nanoscale region, then the problem of the energy-efficient excitation of the local fields would have been solved. However, it is commonly known that it is impossible Is it? We show that this common wisdom is wrong. Using adiabatic transformation, one can transfer energy from the far zone to near field without major losses, with a high efficiency, limited only by absorption in plasmonic waveguides. Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.60 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Adiabatic Nanofocusing of Surface Plasmon Polaritons M. I. Stockman, Nanofocusing of Optical Energy in Tapered Plasmonic Waveguides, Phys. Rev. Lett. 93, 137404-1-4 (2004). Waveguide geometry Lecture Course Nanoplasmonics 2015 Propagation direction z http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.61 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 For Cylindrical Plasmonic Waveguide Electric field of SPP wave for TM0 mode (magnetic field is tangential to the surface, normal to the axis; axially-symmetric solution of the Maxwell curl equations) r < R : E z = I 0 (κ m r ) exp( ikz) I 0 (κ m R ) r > R : Ez = K 0 (κ d r ) exp( ikz) K 0 (κ d R ) ik r < R : Er = I1 (κ m r ) exp(ikz ) κm ik I 0 (κ m R ) r > R : Er = K1 (κ d r ) exp(ikz ) κ d K 0 (κ d R ) Continuity of displacement at the surface: Lecture Course Nanoplasmonics 2015 εm ε d I 0 (κ m R ) I1 (κ m R ) = K1 (κ d R ) κm κ d K 0 (κ d R ) http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.62 7/12/2015 11:31 AM L. Novotny and C. Hafner, Light Propagation in a Department of Physics and Astronomy Cylindrical Waveguide with a Complex, Metallic, Georgia State University Dielectric Function, Phys. Rev. E 50, 4094-4106 Atlanta, GA 30303-3083 (1994) For TM0 mode (magnetic field is tangential to the surface, normal to the axis; axially-symmetric solution), dispersion relation is ε m I1 ( k 0 R k 2 − ε m ) k 2 − ε m I 0 (k0 R k 2 − ε m ) k0 = ω c There is single root: =− ε d K1 ( k 0 R k 2 − ε d ) k 2 − ε d K 0 (k0 R k 2 − ε d ) 10 7.5 5 2.5 Slow SPP. There is no cutoff as -2.5 -5 its wavelength tends to zero (or -7.5 wavevector tends to infinity) -10 Lecture Course Nanoplasmonics 2015 0.5 1 1.5 2 2.5 3 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu k / k0 Lecture 1 p.63 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 k = nω c Introduce effective index: Close to the tip (R 0), this effective index diverges as 1/R: 1 n( R ) ≈ k0 R 4ε d 1 , γ ≈ 0.57721 −ε m log −4ε m − γ εd This describes slowing down and asymptotic stopping of SPP. Important, the time to travel to the tip (singularity) of the conic waveguide logarithmically diverges, R 1 t = ∫ n(r )dr ~ − ln( k0 R) → ∞ c Rmax Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.64 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Adiabatic parameter: δ = R′ d ( R) dR dR( z ) where R′ = is the waveguide grading dz For a plasmonic (TM0) mode, close to the tip Thus, adiabatic parameter stays finite everywhere, including the tip. Correspondingly, the adiabatic (eikonal or WKB) approximation is applicable uniformly over the entire tip. Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.65 7/12/2015 11:31 AM Adiabatic Department of Physics and Astronomy Nanofocusing in Tapered Georgia State University Atlanta, GA 30303-3083Nanoplasmonic Waveguides Propagation direction 103 Intensity of Local Fields at the Surface of Tapered Plasmonic Waveguide (Conic Silver Wire) I 0 z 10 100 20 Coordinate s are in the units of ≈ 100 nm 2 0 2 x M. I. Stockman, Nanofocusing of Optical Energy in Tapered Plasmonic Waveguides, Phys. Rev. Lett. 93, 137404-1-4 (2004). Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.66 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Phase velocity of surface plasmon polaritons Group velocity of surface plasmon polaritons Adiabatic parameter (scaled by 10) k ( R) ≈ 1 R 2ε d 1 − ε m 1 log − 4ε m − γ 2 εd −1 −1 k ∂k v p= ∝ R , vg= ∝R ω ∂ω Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.67 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Local Electric Fields at Surface of Plasmonic Tapered Waveguide Transverse field 40 20 -25 -20 -15 -10 -20 -40 Longitudinal field z 20 10 -25 -20 -15 -10 -10 -20 ≈ 100 nm Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.68 7/12/2015 11:31 AM z Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Local Electric Fields in Cross Section of System Transverse electric field Longitudinal electric field 20 10 Ex 0 20 20 10 z Ez 0 10 2 0x 20 10 z 2 0 x 0 2 0 2 Coordinate s are in the units of ≈ 100 nm Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.69 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Vector of optical electric field for TM0 plasmonic mode of conic waveguide made of silver z 35 Spatial scales are in units of 100 nm Lecture Course Nanoplasmonics 2015 -1 -2 -3 -4 -5 -2-1 0 1 2 1 x http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.70 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Problem Analytically estimate field at the apex as a function of the distance to the apex. Hint: Neglect losses and use energy conservation along the SPP propagation length. Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.71 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Solution to Problem Distance to the apex z and local radius R are proportional, z ∝ R. SPP wave vector is k ∝ R −1. The field localization radius is ∆r ∝ k −1 ∝ R ∝ z. The SPP group velocity is vg ∝ R ∝ z. Conservation of energy flux is E 2v g R 2 ∝ 1, or E 2 z 3 ∝ 1. Correspondingly, E 2 ∝ z −3 is the field scaling. Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.72 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Nano Lett. 7, 334-337 (2007) Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.73 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Latest: E. Verhagen, A. Polman, and L. Kuipers, Nanofocusing in Laterally Tapered Plasmonic Waveguides, Opt. Express 16, 45-57 (2008) Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.74 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.75 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Nano Lett. 7, 27842788 (2007). Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.76 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.77 p.77 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 11:31 p.78 7/12/2015 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Di Fabrizio, E., et. al, Italian patent n. TO2008A000693 23.09.2008 5 nm radius Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.79 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 εm Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.80 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Surface plasmon polaritons propagate along the adiabatic plasmonic taper, nanofocus at the tip, and decay due to Landau damping, producing a nanosource of hot electrons at the tip, which forms a Schottky diode with the substrate Laser beam Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.81 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Geometry and principle of adiabatic-plasmonic hot-electron Schottky nanoscopy Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.82 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.83 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Nano Lett. 11, 4309-4313 Atlanta, GA 30303-3083 (2011) Doi: 10.1021/nl2023299 Nearly transformlimited 16-fs pulse at the apex Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.84 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 Adiabatic Nanofocusing Conclusions •Due to adiabaticity, the back reflection and 3D scattering of SPP is minimal. •The high wave vector of the TM0 SPP makes them dark (no coupling to the far field radiation). •The velocity of SPP tends to zero proportionally to R as they approach the tip: adiabatic slowing down and asymptotic stopping. •This leads to the accumulation of the SPP near the tip and their adiabatic nanofocusing. •Under realistic conditions it is possible to transfer to the tip vicinity ~50% of the initial energy flux, that along with adiabatic stopping leads to the local field-intensity enhancement by three orders of magnitude •The energy and optical field concentration at the tip of a taper is usable to excite a high-sensitivity, low-background SERS from a few molecules Lecture Course Nanoplasmonics 2015 http://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 p.85 7/12/2015 11:31 AM Department of Physics and Astronomy Georgia State University Atlanta, GA 30303-3083 END LECTURE 1 SPIE & LectureOptics Course Nanoplasmonics 2015 http://www.phyhttp://www.phy-astr.gsu.edu/stockman E-mail: mstockman@gsu.edu Lecture 1 1 p.86 Lecture p.86 7/12/2015 11:31 AM