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Optical Antennas

Book Description

This consistent and systematic review of recent advances in optical antenna theory and practice brings together leading experts in the fields of electrical engineering, nano-optics and nano-photonics, physical chemistry and nanofabrication. Fundamental concepts and functionalities relevant to optical antennas are explained, together with key principles for optical antenna modelling, design and characterisation. Recognising the tremendous potential of this technology, practical applications are also outlined. Presenting a clear translation of the concepts of radio antenna design, near-field optics and field-enhanced spectroscopy into optical antennas, this interdisciplinary book is an indispensable resource for researchers and graduate students in engineering, optics and photonics, physics and chemistry.

Table of Contents

  1. Coverpage
  2. Optical Antennas
  3. Title page
  4. Copyright page
  5. Dedication
  6. Contents
  7. Preface
  8. List of contributors
  9. Notation
  10. Part I Fundamentals
    1. 1 From near-field optics to optical antennas
      1. 1.1 The near-field
      2. 1.2 Energies and photons
      3. 1.3 Foundations of near-field optical microscopy
      4. 1.4 Scanning near-field optical microscopy
      5. 1.5 Problems of near-field optical microscopy
      6. 1.6 From near-field optical microscopy to optical antennas
      7. 1.7 Optical antennas
      8. 1.8 Conclusions and outlook
    2. 2 Optical antenna theory, design and applications
      1. 2.1 Introduction
      2. 2.2 Nanoantennas and optical nanocircuits
        1. 2.2.1 Optical nanocircuit theory
        2. 2.2.2 Nanoantennas as optical lumped elements
        3. 2.2.3 Other quantities of interest for optical antenna operation
      3. 2.3 Loading, tuning and matching optical antennas
        1. 2.3.1 Loading, impedance matching and optical wireless links
        2. 2.3.2 Optimizing bandwidth and sensitivity with nanoloads
        3. 2.3.3 Optical nonlinearities as variable nanoloads
      4. 2.4 Conclusions and outlook
    3. 3 Impedance of a nanoantenna
      1. 3.1 Introduction
      2. 3.2 Impedance of a nanoantenna
        1. 3.2.1 Definition
        2. 3.2.2 A vacuum
        3. 3.2.3 A microcavity
        4. 3.2.4 A dipolar nanoantenna
        5. 3.2.5 Comparison of a microcavity and a nanoantenna
        6. 3.2.6 Ohmic and radiative losses
      3. 3.3 Impedance of a quantum emitter
        1. 3.3.1 A two-level system
        2. 3.3.2 Impedance and multiple scattering
      4. 3.4 Applications
        1. 3.4.1 Weak coupling and strong coupling
        2. 3.4.2 Conjugate impedance matching condition
        3. 3.4.3 Maximum absorption by a metallic nanoparticle
        4. 3.4.4 Fluorescence enhancement by metallic nanoparticles
      5. 3.5 Conclusions
    4. 4 Where high-frequency engineering advances optics. Active nanoparticles as nanoantennas
      1. 4.1 Introduction
      2. 4.2 Coated nanoparticles as active nanoantennas
        1. 4.2.1 Configuration
        2. 4.2.2 Theory
        3. 4.2.3 Coated-nanoparticle materials and gain models
      3. 4.3 Results and discussion
        1. 4.3.1 Far-field results
        2. 4.3.2 Near-field results
        3. 4.3.3 Influence of the dipole location
        4. 4.3.4 Additional effects – transparency
        5. 4.3.5 Additional coated-nanoparticle cases
      4. 4.4 Open coated nanocylinders as active nanoantennas
        1. 4.4.1 Nanoparticle model
        2. 4.4.2 Results and discussion
      5. 4.5 Conclusions
    5. 5 Optical antennas for field-enhanced spectroscopy
      1. 5.1 Introduction
        1. 5.1.1 Field enhancement
        2. 5.1.2 Spectral response
        3. 5.1.3 Shape
        4. 5.1.4 Basic ingredients to increase the field
      2. 5.2 Surface-enhanced Raman scattering
      3. 5.3 Surface-enhanced infrared absorption
      4. 5.4 Metal-enhanced fluorescence
      5. 5.5 Quantum effects in nanoantennas
    6. 6 Directionality, polarization and enhancement by optical antennas
      1. 6.1 Introduction
        1. 6.1.1 Optical antennas
        2. 6.1.2 Interaction with single emitters
        3. 6.1.3 Resonant coupling of antenna and emitter
      2. 6.2 Local excitation by optical antennas
        1. 6.2.1 Single emitters as near-field probes
        2. 6.2.2 The monopole antenna case
      3. 6.3 Emission control by optical antennas
        1. 6.3.1 Polarization of single molecule emission
        2. 6.3.2 Directionality of single molecule emission
      4. 6.4 Conclusions and outlook
    7. 7 Antennas, quantum optics and near-field microscopy
      1. 7.1 Introduction
      2. 7.2 Microcavities
      3. 7.3 Antennas
        1. 7.3.1 Small antennas
        2. 7.3.2 Planar antennas
      4. 7.4 Modification of the spontaneous emission rate
        1. 7.4.1 Planar antennas
        2. 7.4.2 Microcavities
        3. 7.4.3 Plasmonic nanoantennas
        4. 7.4.4 Metallo-dielectric hybrid antennas
      5. 7.5 Generation of single photons and directional emission
        1. 7.5.1 Microcavities
        2. 7.5.2 Plasmonic nanoantennas
        3. 7.5.3 Planar antennas
      6. 7.6 Antennas immersed in vacuum fluctuations: Casimir and van der Waals interactions
      7. 7.7 Scanning near-field optical microscopy
      8. 7.8 Outlook
    8. 8 Nonlinear optical antennas
      1. 8.1 Introduction
      2. 8.2 Design fundamentals
        1. 8.2.1 Origin of optical nonlinearities in nanoantennas
        2. 8.2.2 Nonlinear susceptibilities of optical materials
      3. 8.3 Nonlinearities in single nanoparticles
        1. 8.3.1 Nanoscale and macroscale nonlinear phenomena
        2. 8.3.2 Symmetry considerations on the nanoscale
        3. 8.3.3 Nonlinear polarization in nanoparticles
      4. 8.4 Nonlinearities in coupled antennas and arrays
        1. 8.4.1 Enhancement of metal nonlinearities
        2. 8.4.2 Enhancement of nonlinearities in surrounding media
        3. 8.4.3 TPL nonlinear microscopy of coupled particles
      5. 8.5 Conclusions and outlook
    9. 9 Coherent control of nano-optical excitations
      1. 9.1 Introduction
      2. 9.2 Local-field control principles
        1. 9.2.1 Fundamental quantities
        2. 9.2.2 Spectral enhancement
        3. 9.2.3 Local polarization-mode interference
        4. 9.2.4 Local pulse compression
        5. 9.2.5 Optimal control
        6. 9.2.6 Analytic optimal control rules
        7. 9.2.7 Time reversal
        8. 9.2.8 Spatially shaped excitation fields
      3. 9.3 Local-field control examples
        1. 9.3.1 Spatial excitation control
        2. 9.3.2 Spatiotemporal excitation control
        3. 9.3.3 Propagation control
      4. 9.4 Applications
        1. 9.4.1 Space–time-resolved spectroscopy
        2. 9.4.2 Coherent two-dimensional nanoscopy
        3. 9.4.3 Unconventional excitations
      5. 9.5 Conclusions and outlook
  11. Part II Modeling, Design and Characterization
    1. 10 Computational electrodynamics for optical antennas
      1. 10.1 Introduction
      2. 10.2 The numerical solution of Maxwell equations
        1. 10.2.1 Finite-difference time-domain method
        2. 10.2.2 Finite-differences method
        3. 10.2.3 Finite-elements method
        4. 10.2.4 Volume integral-equation method
        5. 10.2.5 Boundary-element method
      3. 10.3 Validity checks
      4. 10.4 Modeling realistic optical antennas
      5. 10.5 Tuning the antenna properties
      6. 10.6 Conclusions and outlook
    2. 11 First-principles simulations of near-field effects
      1. 11.1 Introduction
      2. 11.2 Quantum effects on the near-field
      3. 11.3 Plasmon–exciton hybridization
      4. 11.4 Near-field effects on spectroscopy
        1. 11.4.1 Surface-enhanced Raman scattering
        2. 11.4.2 Surface-enhanced fluorescence
      5. 11.5 Near-field effects on molecular photochemistry
        1. 11.5.1 Early examples of photochemistry
        2. 11.5.2 Photochemical enhancement mechanism
      6. 11.6 Conclusions and outlook
    3. 12 Field distribution near optical antennas at the subnanometer scale
      1. 12.1 Introduction
      2. 12.2 Theoretical background
      3. 12.3 Results
        1. 12.3.1 Sphere dimers
        2. 12.3.2 Nano-rods
        3. 12.3.3 Cylinders
      4. 12.4 Enhancement and localization versus distance in particle dimers
      5. 12.5 Conclusions
    4. 13 Fabrication and optical characterization of nanoantennas
      1. 13.1 Introduction
      2. 13.2 Fabrication of single-crystalline antennas
        1. 13.2.1 Role of the dielectric function
        2. 13.2.2 Effects of geometry and multicrystallinity
        3. 13.2.3 Fabrication issues
        4. 13.2.4 Single-crystalline nanostructures
      3. 13.3 Optical characterization of nanoantennas
        1. 13.3.1 Far-field scattering
        2. 13.3.2 Determining the near-field intensity enhancement
        3. 13.3.3 Emission directivity and coupling to quantum emitters
      4. 13.4 Conclusions and outlook
    5. 14 Probing and imaging of optical antennas with PEEM
      1. 14.1 Introduction
      2. 14.2 Photoemission electron microscopy
        1. 14.2.1 Instrumental setup
        2. 14.2.2 The photoemission process
      3. 14.3 Near-field investigation of nanostructured surfaces
        1. 14.3.1 Local near-field mapping
        2. 14.3.2 Imaging of surface plasmon polaritons
        3. 14.3.3 Observing and controlling the near-field distribution
        4. 14.3.4 Nonlinearities on structured surfaces
      4. 14.4 Time-resolved two-photon photoemission
        1. 14.4.1 Phase-averaged time-resolved PEEM
        2. 14.4.2 Phase-resolved PEEM
      5. 14.5 Other potential applications
        1. 14.5.1 Attosecond nanoplasmonic field microscope
        2. 14.5.2 Magneto-plasmonics
      6. 14.6 Conclusions and outlook
    6. 15 Fabrication, characterization and applications of optical antenna arrays
      1. 15.1 Introduction
      2. 15.2 Theory of antenna arrays
        1. 15.2.1 The array factor
        2. 15.2.2 Two-dimensional planar arrays and phased arrays
        3. 15.2.3 Directionality enhancement
      3. 15.3 Differences between RF and optical antenna arrays
        1. 15.3.1 Effective antenna length
        2. 15.3.2 Differences in antenna emission patterns
        3. 15.3.3 Antenna losses
      4. 15.4 The optical Yagi–Uda antenna – linear array of plasmonic dipoles
        1. 15.4.1 Fabrication and characterization of transmitting optical Yagi–Uda antennas
        2. 15.4.2 Design of receiving optical Yagi–Uda antennas
        3. 15.4.3 Characterization of receiving optical Yagi–Uda antenna
      5. 15.5 Two-dimensional arrays of optical antennas
        1. 15.5.1 Characterization of planar optical antenna arrays
        2. 15.5.2 Fabricating three-dimensional nanoantennas
        3. 15.5.3 Optical properties
        4. 15.5.4 Experimental characterization
      6. 15.6 Applications of optical antenna arrays
        1. 15.6.1 Phased arrays for optical wavelengths
        2. 15.6.2 Optical antenna links
    7. 16 Novel fabrication methods for optical antennas
      1. 16.1 Introduction
      2. 16.2 Conventional methods to create nanoantennas
      3. 16.3 Soft nanolithography
        1. 16.3.1 Master
        2. 16.3.2 Elastomeric mask
        3. 16.3.3 Nanopatterned template
        4. 16.3.4 Optical antenna arrays
      4. 16.4 Strongly coupled nanoparticle arrays
      5. 16.5 Metal–insulator–metal nanocavity arrays
      6. 16.6 Three-dimensional bowtie antenna arrays
      7. 16.7 Conclusions and outlook
    8. 17 Plasmonic properties of colloidal clusters: towards new metamaterials and optical circuits
      1. 17.1 Introduction
      2. 17.2 Self-assembled magnetic clusters
      3. 17.3 Plasmonic Fano-like resonances
      4. 17.4 DNA cluster assembly
      5. 17.5 Conclusions and outlook
  12. Part III Applications
    1. 18 Optical antennas for information technology and energy harvesting
      1. 18.1 Introduction
      2. 18.2 Coupling plasmonic antennas to semiconductors
      3. 18.3 Plasmonic antennas for information technology and energy harvesting
      4. 18.4 Operation of semiconductor-based optical antennas
      5. 18.5 Semiconductor antennas for information technology and energy harvesting
      6. 18.6 Conclusions and outlook
    2. 19 Nanoantennas for refractive-index sensing
      1. 19.1 Introduction
      2. 19.2 An overview of plasmonic sensing
        1. 19.2.1 Bulk sensitivity
        2. 19.2.2 Molecular sensing
      3. 19.3 Recent trends in plasmonic sensing
        1. 19.3.1 Fano resonances
        2. 19.3.2 Alternative sensing schemes
        3. 19.3.3 Sensing with nanoholes
        4. 19.3.4 Plasmonic sensing for materials science
      4. 19.4 Conclusions and outlook
    3. 20 Nanoimaging with optical antennas
      1. 20.1 Introduction
      2. 20.2 The diffraction limit and spatial resolution
      3. 20.3 Evanescent waves and metals
        1. 20.3.1 Excitation of surface plasmon-polaritons with light
        2. 20.3.2 Optical antennas
      4. 20.4 Tip-enhanced Raman spectroscopy
        1. 20.4.1 Spatial resolution in TERS
        2. 20.4.2 Imaging intrinsic properties through TERS
      5. 20.5 Further improvement in imaging through optical antennas
        1. 20.5.1 Combining optical antennas with mechanical effects
      6. 20.6 Optical antennas as nanolenses
      7. 20.7 Conclusions and outlook
    4. 21 Aperture optical antennas
      1. 21.1 Introduction
      2. 21.2 Enhanced light–matter interaction on nanoaperture antennas
        1. 21.2.1 Single apertures
        2. 21.2.2 Single apertures surrounded by surface corrugations
        3. 21.2.3 Aperture arrays
      3. 21.3 Biophotonic applications of nanoaperture antennas
        1. 21.3.1 Enhanced fluorescence detection and analysis
        2. 21.3.2 Molecular sensing and spectroscopy with aperture arrays
      4. 21.4 Nanophotonic applications of nanoaperture antennas
        1. 21.4.1 Photodetectors and filters
        2. 21.4.2 Nanosources
      5. 21.5 Conclusions
  13. References
  14. Index