Subwavelength optical solitons

In this chapter, we review the main physical properties and some applications of optical solitons whose size is much smaller than the optical wavelength, the so-called subwavelength optical solitons. We discuss the physical conditions under which the formation of such subwavelength optical solitons becomes possible and introduce several optical material configurations in which these solitons have been observed and investigated. In particular, we consider two plasmonic systems, that is, one- and two-dimensional arrays of metallic nanowires and systems of layered graphene sheets, and two types of dielectric photonic nanowires, namely silicon photonic nanowires implemented onto the planar silicon-on-insulator material platform and optical fibers made of silicon. For all these physical systems we consider the ingredients needed to generate optical solitons in the subwavelength regime, as well as some of their physical properties, such as stability, dynamics, and soliton interactions. In our review, we cover both theoretical methods employed to describe the optical properties of subwavelength solitons, such as coupled-mode theory, as well as key experimental studies of such solitons.