Nematicons: Spatial Optical Solitons in Nematic Liquid Crystals

Chapter 1: Nematicons

Gaetano Assanto, Alessandro Alberucci and Armando Piccardi

Nonlinear Optics and OptoElectronics Lab, University ROMA TRE, Rome, Italy

1.1 Introduction

The term nematicon was coined to denote the material, nematic liquid crystals (NLC), supporting the existence of optical spatial solitons via a molecular response to light, a reorientational nonlinearity. Nematicons was first used in the title of Reference 1, after three years since the first publication on reorientational spatial optical solitons in NLC [2]. Since then, a large number of results, including experimental, theoretical, and numerical, have been presented in papers and conferences and formed a body of literature on the subject. In this chapter we attempt to summarize the most important among them, leaving the details to the specific articles but trying to provide a feeling of the amount of work carried out in slightly more than a decade.

1.1.1 Nematic Liquid Crystals

Liquid crystals are organic mesophases featuring various degrees of spatial order while retaining the basic properties of a fluid. In the absence of absorbing dopants, they are excellent dielectrics, transparent from the ultraviolet to the mid-infrared, with highly damaged thresholds, relatively low electronic susceptibilities, and significant birefringence at the molecular level and in the nematic phase. In the latter phase, their elongated molecules have the same average angular orientation, although their individual location is randomly ...