Periodic oscillations of dark solitons in nonlinear optics

Dark solitons draw much attention due to their stable transmission property in nonlinear optics. In this paper, the variable coefficient nonlinear Schrödinger equation is solved by the Hirota method, and a new type of dark solitons with periodic oscillations is presented. Oscillations can be achieved without any external influence on them. The frequency and amplitude of dark soliton oscillations can be controlled by adjusting corresponding parameters. We hope those results are helpful for the dark soliton investigation.