Due to its unique properties, soliton-based supercontinuum generation (SCG) in nonlinear optical fibers has been identified as an extremely promising platform for the desired generation of broadband light in various spectral regions including the mid-IR. In general, SCG relies on spectral broadening of an initial narrowband pulse, which is particularly effective in optical fibers due to the long interaction lengths of light and matter.
The main goal of this project is to understand soliton dynamics and soliton-based supercontinuum generation at mid-IR wavelengths in liquid-core fibers, with the aim of unlocking new nonlinear physics based on a tunable, flexible, and integrated waveguide platform. Unlike many solid-state materials, liquids offer unique properties for nonlinear light generation at mid-IR wavelengths: In addition to broad mid-IR transmittances and exceptionally high nonlinear refractive indices, the sophisticated (non-instantaneous) nonlinear response of liquids enables the generation of supercontinua with exceptionally high pulse-to-pulse stability (i.e., high coherence) at pulse lengths (several hundred femtoseconds); typical solid-state systems yield very incoherent, modulation-unstable supercontinua. This stability, recently discovered by the applicant, is of great importance for future light sources, since typical ultrashort pulse lasers at mid-IR wavelengths (>2μm) have pulse lengths >100 fsec, making liquid-core fibers particularly attractive due to better coherence at comparatively long pulse lengths. Another key feature of the liquid-core fiber approach is the possibility to control and manipulate the pulse dispersion by using different liquids or their mixtures or by external influences such as temperature. 

The project is supported by DFG grant number SCHM 2655/12-1, AOBJ: 649585.