Angular momentum of elliptically polarised cnoidal waves and breathers in a nonlinear gyrotropic medium with frequency dispersion

We have analysed expressions for the spin part of the density vector of the angular momentum (moment of momentum) of elliptically polarised cnoidal waves and breathers propagating in an isotropic gyrotropic medium with second order frequency dispersion and spatial cubic nonlinearity dispersion. We have found that, due to nonlinear gyration, the density of the angular momentum depends on time and propagation coordinates.