Nonlinear Optics of Fibre Waveguides
The development of a technology for the production of optical fibres has made it possible to significantly expand the horizons of nonlinear optics. Thus, the dependence of the linear and cubic dielectric susceptibilities of the fibre material on the frequency determine the material dispersion of the linear and nonlinear induced polarizations. Let us also assume that the nonlinear response of the polarization of the medium is instantaneous, and the group velocity of the light pulse does not depend on its intensity. Thus, optical fibres based on quartz glass, characterized by a low nonlinearity with respect to other materials, can provide a significant increase in the efficiency of nonlinear processes due to the large length of interaction of radiation with matter. The nonlinear polarization induced by the total light field has terms separated as'dots', which denotes the presence of terms oscillating with new total and difference frequencies.