Preface

Nanophotonics has recently attracted interest for its potential applications in microscopy, sensing, imaging, medicine, light sources, and functional devices. These applications are based on the interaction of light and matter at the nanoscale. The plasmonic oscillations in metallic structures are essential in such a case due to the strong enhancement of the light-matter interactions near the metal surface in small volumes of nanostructures. Plasmonic excitations at the interface of the metal and dielectric or surface plasmon polaritons (SPPs) can exist as transverse magnetic (TM) waves. SPPs are characterized by limited propagation length and confinement at the subwavelength scale in the direction perpendicular to the propagation direction. The nonlinear optical effects are enhanced in plasmonic structures due to the strong localized electromagnetic fields and the influence of the surrounding medium on the plasma excitation parameters. Plasmonic applications in nonlinear optics result in the enhancement of optical nonlinearity, substantial decrease of photonic device dimensions, and the possibility of ultrafast optical signal processing.

This book examines nonlinear optical effects in nonlinear nanophotonics, plasmonics, and novel materials for nonlinear optics. It includes six chapters organized into four sections.

Section 1 includes an introductory chapter that investigates the interaction of an electromagnetic field and free electron gas in metals. The analysis is based on the solution of Maxwell's equations and the equation of motion for a free electron in an external electric field. As a result, different types of plasmonic excitations such as volume plasmons, localized surface plasmons, and surface plasmon polaritons emerge. The introductory chapter also discusses the peculiarities of the nonlinear optical phenomena in plasmonic nanostructures and metamaterials.

Section 2 includes Chapter 2, which considers the foundations, the peculiarities of nonlinear optical phenomena in nanophotonics, and the possible applications of nanophotonics.

Section 3 consists of three chapters that discuss novel materials for nonlinear optics. Chapter 3 presents a new method of preparing metal nanoparticles and investigates the nonlinear properties of these nanoparticles experimentally. Chapter 4 studies the structural-compositional relationship of polymeric materials used in optoelectronic and photonic applications. Chapter 5 reviews the nonlinear optical properties of photonic glasses. In particular, the chapter focuses on optical glasses doped with metal nanoparticles.

Section 4 consists of Chapter 6, which demonstrates a new solution of the nonlinear Schrödinger equation (NLSE) for 5G broadband millimeter waves.

This book is a useful resource that may be interesting for the researchers and engineers occupied studying and working in nonlinear optics, nanophotonics, and devices for optical signal processing.

> **Boris I. Lembrikov** Department of Electrical Engineering and Electronics, Holon Institute of Technology (HIT), Holon, Israel

Section 1 Introduction
