Variable high-contrast all-optical self-switching of femtosecond solitonic pulses in multi-dual-core optical fiber with distributed optical asymmetry.

Effective alloptical selfswitching of Cband femtosecond pulses, driven by pulse energy in a nonlinear fiber coupler, was experimentally investigated. A key contribution of this work is the detailed analysis of optical asymmetry between the two fiber cores influencing the switching mechanism. The asymmetry was examined using a multicore, highly nonlinear softglass fiber containing five noninteracting dualcore units with distinct propagationconstant mismatches. The study systematically evaluated the fiber length and input polarization effects, tracking changes in the output intensity distribution and extending the analysis to the spectral domain. Different regimes of highcontrast switching based on soliton selftrapping were observed and correlated with the degree of optical asymmetry. Beyond its fundamental insights, this work advances the state of the art by reducing the required switching energy, shortening the fiber length, and increasing the number of achievable switching steps.