Generation of bright and dark solitons in photonic nanowire

In this paper, we generate bright as well as dark soliton type ultrashort laser pulses in a photonic nanowire. The pulse evolution in the photonic nanowire is described by higher order nonlinear Schrödinger equation with an additional effect relating to the nonlinear change of group velocity, which, in turn, is proportional to the field intensity. The pulse evolution equation is solved by coupled amplitude-phase method. Further, we calculate the minimum power required for realizing the ultrashort laser pulses. The main crux of this work stems from the generation of ultrashort pulses by an entirely new nonlinear effect involving change of group velocity.