Optical beam propagation inside a graded-index fiber with saturable nonlinearity
Phys. Rev. A 113, 043514 – Published 14 April, 2026
DOI: https://doi.org/10.1103/tkmj-yg2l
Abstract
We study theoretically the spatial evolution of optical beams inside a graded-index fiber exhibiting saturable nonlinearity. Utilizing an approach based on the variational principle, we identify the existence of bistable spatial solitons inside such a nonlinear medium, whose stability, analyzed through a linear stability analysis, is due to the saturating nature of the nonlinearity. Spatial solitons adhere to a specific amplitude-width relationship. Any deviation from this relationship leads to oscillating-type solutions with a period that increases with the saturation level of the nonlinearity. Theoretically calculated values of this period agree well with numerical findings.
