Negative frequency effects in nonlinear optics

Abstract

In this thesis we analyse the impact of the new terms that appear in the nonlinear polarisation of the equations relevant to nonlinear x(3) optical materials when the slowly varying envelope approximation (SVEA) is not applied. These new terms introduce new nonlinear interactions between the positive and negative frequency parts of the spectrum of an optical pulse, giving rise to novel nonlinear phenomena that were not present in the usual models based in SVEA, like the ubiquitous nonlinear Schrodinger equation (NLSE). The analysis carried out in this thesis is theoretical, with both numerical simulations and analytical results presented. These results predict new frequency generation processes that can have a considerable impact in ultrashort pulse propagation and supercontinuum generation. We also discuss the experimental need for this extended model, as well as some possible signatures of these novel frequency generation processes in recent experiments.