Dramatic Enhancement of Supercontinuum Generation in H$_2$O by Non-Harmonic Two-Color Excitation

Abstract: We demonstrate a dramatic enhancement of supercontinuum generation (SCG) in H$_2$O driven by non-harmonic two-color laser fields, where pump and seed frequencies are not integer multiples. This scheme yields a broadband SC spectrum enhanced by approximately three orders of magnitude over the single-color case. Systematic experiments and theoretical analysis, including isotope effects, show that the enhancement arises from soliton compression with resonant dispersive wave (RDW) emission, phase- and group-velocity-matched four-wave mixing (FWM), and cross-phase modulation (XPM), offering a versatile route to stronger SCG and noise suppression in broadband spectroscopy in H$_2$O, an emerging topic in attosecond and surface physics.