Liquid‐Core Optical Fibers—A Dynamic Platform for Nonlinear Photonics

Abstract

Softphotonics has emerged as a new discipline that utilizes soft matter (i.e., liquids, gels, bio‐materials) as waveguide materials with versatile functionalities. The flexible properties of soft matter show great potential for further exploiting nonlinear in‐fiber phenomena to gain more insights into their fundamental dynamics and to inspire a new generation of broadband optical light sources and signal processors that are adaptable, reconfigurable, and biocompatible. In particular, incorporating solvents with extraordinary temperature sensitivity, miscibility, and nonlinearity into optical fibers has spawned a series of inventions and fundamental scientific findings over the last decades. This review highlights the current state of development of nonlinear photonics in liquid‐filled fibers. The current state of knowledge in the linear and nonlinear material properties of the most prominent solvents (CS₂, CCl₄, C₂Cl₄, benzene and its derivatives) are revisited, and recent advances in nonlinear liquid‐core fiber optics, including a special highlight on phenomena that are unique to liquids, such as modified solitary states and local dispersion control are summarized. Finally, the leading scientific challenges for advancing the field, which highlights liquid‐core fibers as a rich platform for science and technology, are discussed.