Angular momentum of elliptically polarized cnoidal waves and breathers in a nonlinear gyrotropic medium with frequency dispersion Текст научной статьи по специальности «Физика»

LMI-O-8

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

K. Grigoriev1,2, V. Petnikova1, V. Makarov1,2

1Lomonosov Moscow State University, Faculty of physics, Moscow, Russian Federation 2Lomonosov Moscow State University, International Laser Center, Moscow, Russian Federation

We have analyzed expressions for the spin part of the density vector of the angular momentum of elliptically polarized cnoidal waves and elliptically polarized breathers propagating along z axis in an isotropic gyrotropic medium with second order frequency dispersion and spatial dispersion of cubic nonlinearity. A peculiar feature of the obtained analytical expressions for z component of the density vector of the angular momentum is the variety of forms of their dependence on the running time t and of the nonlinear gyrotropic medium parameters. For all degenerate solutions of both elliptically polarized cnoidal waves and breathers, the density vector of the spin part of the angular momentum is proportional to the nonlinear gyration parameter and differs from zero only in an isotropic medium with spatial dispersion of cubic nonlinearity.

The frequency of oscillations of Jacobi elliptic functions determining the solution in the form of elliptically polarized cnoidal waves is high enough to produce real sample oscillations. The time-averaged contribution of these oscillations is proportional to the nonlinear gyration parameter. The z component of the density vector of the angular momentum of elliptically polarized Ahmediev breather and the Kuznetsov - Ma soliton also depend on t and z. For the Akhmediev breather, it is periodic in t and soliton-like in z, and for the Kuznetsov - Ma soliton, it is soliton-like in t and periodic in z. The values of the spin part of the angular momentum averaged over time and propagation coordinate for Ahmediev breather and the Kuznetsov - Ma soliton are nonzero only in the medium with spatial dispersion of cubic nonlinearity.

This work was supported by the Russian Foundation for Basic Research (Grant No. 19-0200069).