Supercontinuum generation in a few-mode liquid-core fiber

Abstract

Liquid-core fibers have been widely used for supercontinuum generation because of the high nonlinearity and high transparency of selected liquids. These fibers are fabricated using silica capillaries with micrometer core diameters infiltrated with nonlinear liquids. Since nonlinear liquids typically have a refractive index much higher than silica, this results in multimode guidance, especially in large core fibers. This study focuses on numerically investigating supercontinuum generation in a few-mode liquid-core (${\text{CS}}_2$-core) fiber by using a commercial femtosecond laser with a central wavelength of 1560 nm and a pulse duration of 100 fs. The fiber has a core diameter of $5\mu m$ and supports 24 polarized modes. Due to the high noninstantaneous nonlinearity of ${\text{CS}}_2$, the liquid-core fiber can achieve supercontinuum generation with higher coherence compared to solid-core fibers, for both linear and circular polarization. Additionally, this work investigates the interaction among the four polarized components of the first high-order mode (${\text{LP}}_{\text{11}}$), pointing out the differences in power transfer between the polarized modes in the case of linear and circular polarization. The interaction between ${\text{HE}}_{\text{11,x}}$ and ${\text{TM}}_{\text{01}}$ modes with all existing modes is also discussed.