Periodic and localized waves in parabolic-law media with third- and fourth-order dispersions
We study the propagation of femtosecond light pulses inside an optical fiber medium exhibiting higher-order dispersion and cubic-quintic nonlinearities. Pulse evolution in such system is governed by a higher-order nonlinear Schr% \"{o}dinger equation incorporating second-, third-, and fourth-order dispersions as well as cubic and quintic nonlinearities. Novel classes of periodic wave solutions are identified for the first time by means of an appropriate equation method. Results presented indicated the potentially rich set of periodic waves in the system under the combined influence of higher-order dispersive effects and cubic-quintic nonlinearity. Solitary waves of both bright and dark types are also obtained as a limiting case for appropriate periodic solutions. It is found that the velocity of these structures is uniquely dependent on all orders of dispersion. Conditions on the optical fiber parameters for the existence of these stable nonlinear wave-forms are presented as well.