Keywords
Abstract
The expressions for the additional terms to the electromagnetic field energy density, energy flux density, momentum density, momentum flux density, components of angular momentum density and components of anglular momentum flux density tensor in a medium with nonlocality of the n-th order nonlinear optical response are obtained from the Maxwell equations system for the case when the number of the interacting waves with different frequencies is less than or equal to n (frequency-degenerate processes). It is shown that the intrinsic symmetry relations between the components of both local and nonlocal nonlinear susceptibility tensors make it impossible to obtain the correct formulas for the aforementioned fundamental characteristics of the electromagnetic field as a particular case of the already known expressions for these quantities related to the nonlinear interaction of n + 1 waves with absolutely different frequencies if we put some frequencies equal to each other. As an example, we discuss the obtained additional terms caused by nonlocal nonlinear optical response of the medium in cases of self-focusing, second- and third-harmonic generation.