Table 1 Summary of parameters in the SGNLSE: physical meanings and roles.
Symbol | Physical meaning and role in SGNLSE |
|---|---|
\(\digamma (x,t)\) | is the complex wave function representing the wave soliton. It evolves under the combined effects of dispersion, nonlinearity, and stochastic perturbations. |
\(|\digamma |^{2m}\), \(|\digamma |^{2n}\) and \(|\digamma |^{2p}\) | represent nonlinear interactions between the wave function and its own intensity, and model intensity-dependent dispersion and refractive index behavior. |
a | is the nonlinearity coefficient associated with the standard nonlinear term \(a|\digamma |^{2n}\digamma\). It governs self-phase modulation (SPM). A positive a induces focusing nonlinearity, while a negative a induces defocusing effects. Plays a central role in shaping soliton solutions. |
b | is the coefficient of the higher-order nonlinear term \(b|\digamma |^{2p}\digamma\), used to model complex nonlinear behaviors such as multi-photon absorption or saturation effects. Influences the richness and diversity of exact solution structures. |
\(\delta\) | is the noise strength parameter for the multiplicative stochastic term \(\delta \digamma \, \frac{dW(t)}{dt}\). It determines the intensity of the stochastic influence on the wave, introducing amplitude fluctuations and phase jitter. Higher values lead to greater randomness in soliton behavior. |
W(t) | is the Wiener process (Brownian motion), a stochastic process with independent Gaussian increments. Models environmental randomness such as thermal fluctuations or refractive-index disorder. Its derivative formally appears as white noise in the SGNLSE. |
m | is power index of the nonlinear dispersion term \((|\digamma |^{2m} \digamma )_{xx}\). It generalizes the dispersive behavior, allowing the equation to model intensity-dependent dispersion observed in certain optical media or plasmas. |
n | is power index in the standard nonlinear term \(a|\digamma |^{2n}\digamma\). It generalizes the Kerr nonlinearity and determines the self-focusing/defocusing strength. |
p | is power index in the higher-order nonlinear term \(b|\digamma |^{2p}\digamma\). Controls the degree and type of higher-order nonlinearity contributing to the wave dynamics. |
\(\beta\) | is spatial scaling parameter introduced in the transformation \(\zeta = \beta x - vt\), where \(\zeta\) is a traveling coordinate. It controls the width and spatial frequency of the soliton and enables conversion of the SGNLSE into a solvable ordinary differential equation. |
\(\omega\) | is the temporal frequency term appearing in the solution’s phase factor \(e^{i[\omega t + \delta W(t) - \delta ^2 t]}\). It governs the oscillatory time evolution of the soliton and couples with the noise to influence stability. |