Liquid-core liquid-cladding optical fibers sustained by light radiation pressure: Electromagnetic model and geometrical analog

We present an electromagnetic model describing liquid-core liquid-cladding optical fibers sustained by light radiation pressure that encompass the contribution of all the allowed propagating modes. Various sequences of unstable and stable equilibrium liquid column diameters are found above a threshold power. The nontrivial relationship between a single-valued or multivalued column diameter with a mono- or multimodal structure of the electromagnetic field is analyzed, and the influence of the light-matter interaction geometry is estimated. Moreover, we propose a geometrical interpretation based on a ray optics approach that brings an intuitive understanding of the role played by the higher-order propagation mode in the occurrence of a multistable liquid-core behavior.