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Abstract The generation of tailored supercontinua is essential for studying ultrafast light-matter interactions and for a variety of practical applications requiring broadband light. Liquid-core fibers (LCFs) have emerged as an innovative nonlinear photonic platform, demonstrating high efficiency in nonlinear frequency conversion. In this study, we showcase that LCFs provide a stable platform for ultrafast supercontinuum generation in a selected higher-order vector mode at $$1.55\;\upmu \hbox {m}$$ 1.55 μ m . Specifically, we demonstrate soliton fission and double-dispersive wave generation using a radially polarized mode in a $$\hbox {CS}_{2}$$ CS 2 -silica liquid-core fiber. The experiments were performed in a temperature-controlled laboratory, showing excellent stability with no evidence of fiber degradation, material degradation, or drift-induced changes in mode excitation over extended periods under standard environmental conditions. Our results confirm that liquid-core fibers are a reliable platform for nonlinear photonics, suitable for applications such as computationally tailored supercontinuum generation, single pulse spxectroscopy, and tailored light sources, all of which rely on consistent and stable nonlinear frequency conversion.

Abstract Supercontinuum generation enabled a series of key technologies such as frequency comb sources, ultrashort pulse sources in the ultraviolet or the mid-infrared, as well as broadband light sources for spectroscopic methods in biophotonics. Recent advances utilizing higher-order modes have shown the potential to boost both bandwidth and modal output distribution of supercontinuum sources. However, the strive towards a breakthrough technology is hampered by the limited control over the intra- and intermodal nonlinear processes in the highly multi-modal silica fibers commonly used. Here, we investigate the ultrafast nonlinear dynamics of soliton-based supercontinuum generation and the associated mode coupling within the first three lowest-order modes of accurately dispersion-engineered liquid-core fibers. By measuring the energy-spectral evolutions and the spatial distributions of the various generated spectral features polarization-resolved, soliton fission and dispersive wave formation are identified as the origins of the nonlinear broadening. Measured results are confirmed by nonlinear simulations taking advantage of the accurate modeling capabilities of the ideal step-index geometry of our liquid-core platform. While operating in the telecommunications domain, our study allows further advances in nonlinear switching in emerging higher-order mode fiber networks as well as novel insights into the sophisticated nonlinear dynamics and broadband light generation in pre-selected polarization states.