Higher-order effects on the properties of the optical compact bright pulse: Collective variable approach

The effects of higher-order (HO) terms on the properties of the compact bright (CB) pulse described by the dispersionless nonlocal nonlinear Schrödinger (DNNLS) equation are investigated. These effects include third-order dispersion (TOD), the Raman term, and the time derivative of the pulse envelope. By means of the collective variable method, the dynamical behavior of the pulse amplitude, width, frequency, velocity, phase, and chirp during propagation is pointed out. The results indicate that the CB pulse experiences a self-frequency shift and self-steepening, respectively, in the presence of an isolated Raman term and the time derivative of the pulse envelope and acquires a velocity as the result of the TOD effect. In addition, TOD may also induce the breathing mode inside the variation of the pulse parameters when the width of the input pulse is slightly less than that of the unperturbed CB pulse. The combination of these terms, indispensable for describing ultrashort pulses, reproduces all these phenomena in the CB pulse behavior. Further, other properties are observed, namely, the pulse decay, the breathing mode even when the unperturbed CB pulse is taken as the input signal, and the attenuated pulse. These results are in good agreement with the results of the direct numerical simulations of the DNNLS equation with HO terms.