World Scientific Handbook of Metamaterials and Plasmonics

The following sections are included:

• Preface by Main Editor
• Preface by Volume Editor
• Contents

This chapter is intended to serve both as a brief introduction and a reference frame for the rest of the chapters of this book. First, we analyze the optical response of metals, describing why noble metals are best suited for plasmonics in the optical regime. We also show the theoretical foundations of the surface plasmons supported by two-dimensional (2D) metal surfaces, with special emphasis on analyzing their dispersion relations, confinement and propagation lengths. A historical note on the discovery of these surface electromagnetic (EM) modes in the fields of Optics and Condensed Matter Physics is also presented. Finally, the surface plasmon modes supported by metal particles (0D structures) and 1D metal waveguides and their feasible applications are briefly introduced.

Antennas are widely used to couple efficiently electromagnetic waves with subwavelength emitters and receivers. In this chapter we discuss how the concept of antenna can be used in the optics regime to control light-matter interaction processes such as absorption, scattering or spontaneous emission by a quantum system such as an atom, a molecule or a quantum dot. The aim of this basic introduction is to establish connections between the electrical engineer, the optics and the cavity quantum electrodynamics point of view.

The following sections are included:

• Introduction
• Linear-Response Nonlocal Theory
• Linear-Response Electrodynamics
• Hydrodynamic Equation of Motion: Drift-diffusion Theory
• Boundary Conditions
• Numerical Solutions
• Estimates of Characteristic Material Parameters
• The Relation of GNOR to Higher-level Descriptions
• A Test Case for GNOR Theory: Monomers and Dimers
• Surface-Enhanced Landau Scattering: ab initio Insight
• Surface-enhanced Landau Scattering: Microscopic Insight
• Concluding Remarks
• Acknowledgments
• References

Excitation of localized surface plasmon resonances in metal nanoparticles and nanoparticle assemblies allows to manipulate light at nanometer scales well beyond the wavelength and opens the possibility of many applications. The complexity of the variety of methods to fabricate plasmonic structures and the sophistication of optical characterization techniques invites for completing the plasmonics landscape with a comprehensive theoretical understanding of the optical response. Classical approaches based on the solution of Maxwell’s equations using local (model or empirical) bulk dielectric constant are extensively used to describe plasmonic systems and gain the necessary intuition. At the same time, recent experimental and theoretical developments have clearly demonstrated that as soon as nanometer and subnanometer scales are approached, quantum effects such as tunneling, non-local screening and the atomistic structure of the metal nanoparticles become important. In this chapter, we discuss the major manifestations of quantum effects in the properties of localized plasmons, with particular emphasis on the underlying physics.

Transformation optics (TO) is a recently developed theoretical tool that makes possible an unprecedented control over the propagation and confinement of electromagnetic (EM) fields at both supra- and sub-wavelength scales. In the context of metamaterial science, TO establishes a direct link between a desired EM phenomenon and the material characteristics required for its occurrence. More recently, this powerful framework has been successfully applied to the study of surface-plasmon-assisted phenomena, such as light collection and concentration by nano-antennas, the emergence of non-local effects in the optical response of nanostructured metals, or the van der Waals interactions between particles separated by nanometric distances. In this chapter, the fundamentals of TO are reviewed, and recent advances on the TO design and description of plasmonic devices are presented with special focus on the deep insights provided by this largely analytic approach.

With a high surface to volume ratio and strongly varying properties on nanometer length scales, the dynamics of nanomaterials are often very different from those of bulk materials. Ultrafast single-particle spectroscopy provides a means of accessing these properties, but has to overcome challenges related to the diffraction limit and small cross-sections of single nanoobjects. Several far-field and near-field approaches have been introduced capable of achieving single-particle resolution in ultrafast spectroscopy. By designing plasmonic nanosystems as an antenna, one can exploit local-field enhancements and interactions between the antenna and its environment to design ultrafast nonlinear response. Design considerations for hybrid systems combining plasmonic and nonlinear materials are discussed together with the progress made in this area.

The following sections are included:

• Introduction
• Linear Optical Response of Plasmonic Systems
• Ultrafast Nonlinear Plasmonics
• Ultrafast Pump-probe Spectroscopy: Exciton–Plasmon Rabi Oscillations in Hybrid Metal-molecular Nanostructures
• Summary and Conclusions
• Acknowledgments
• References

Graphene plasmons (GPs) — electromagnetic fields coupled to Dirac electrons in graphene sheet — have recently attracted a great attention in different scientific fields, particularly in condensed matter physics and photonics. In this chapter, we aim to review the most relevant results in graphene plasmonics reported during the last few years. We consider important properties of GPs, such as their dispersion, confinement, losses, etc. We discuss various mechanisms of efficient coupling between free-space waves and GPs. In more detail, we theoretically illustrate an example of GPs excitation by a diffraction grating.

The following sections are included:

• Introduction
• Theory
• Simulation Approaches
• Quasistatic Approximation and Modal Decomposition
• Results
• Summary and Outlook
• References

Photothermal processes in plasmonic nanoparticles have been at the basis of a decade of burgeoning activities that set the field of thermoplasmonics. Here, we present an overview of this dynamic research area. Specifically, we detail the underlying physics of heat generation in plasmonic nanoparticles. Key aspects related to heat generation processes, determination of temperature increase (both numerically and experimentally), time scales, collective effects and heating under pulsed illumination are first addressed. Subsequently, we review the main targeted applications, namely photothermal cancer therapy, nanochemistry, thermophotovoltaics and heat-assisted magnetic recording.

The following sections are included:

• Introduction
• Overview of s-SNOM
• Experimental Setups
• Background Suppression
• Examples
• Conclusion
• References

The rapidly increasing interest in plasmonic nanoparticles (NPs) has driven the scientific community to explore a variety of innovative procedures for their production, including advanced nanolithography techniques, sacrificial templates and many others. While these techniques provide high-quality nanomaterials, scale-up is hindered due to potentially complicated and expensive processes. In this respect, finding complementary and alternative approaches is required. Bench-top chemical strategies do not suffer in principle from such limitations and are thus of tremendous interest in plasmonic materials design. We address in this chapter, the most commonly used methods of preparing plasmonic NPs by wet chemistry approaches. Rather than giving a list of manufacturing routes, which would be nearly impossible taking into account the vast available literature, we aim at providing the reader with the necessary knowledge to apprehend this field.

The following section is included:

• Index