Cubic–quartic optical soliton perturbation and modulation instability analysis in polarization-controlled fibers for Fokas–Lenells equation

The objective of this study is to investigate miscellaneous wave structures for perturbed Fokas–Lenells equation (FLE) with cubic-quartic dispersion in polarization-preserving fibers. Based on the improved projective Riccati equations method, various types soliton solutions such as bright soliton, combo dark–bright singular and are constructed. Additionally, a set periodic waves also retrieved. dynamical behaviors some obtained depicted provide key understanding physics model. modulation instability FLE reported by employing linear stability analysis which shows that all stable.