Breakthrough in water-based light generation: 1,000-fold enhancement of white-light output using non-harmonic two-color femtosecond lasers Experimental demonstration that non-harmonic two-color femtosecond excitation produces a ~1,000× stronger supercontinuum in water compared to conventional single-color excitation. Credit: Institute for Molecular Science / Tsuneto Kanai

Scientists at Japan's Institute for Molecular Science have achieved a 1,000-fold enhancement in white-light generation inside water by using non-harmonic two-color femtosecond laser excitation. This previously unexplored approach in liquids unlocks new nonlinear optical pathways, enabling a dramatic boost in supercontinuum generation. The breakthrough lays a foundation for next-generation bioimaging, aqueous-phase spectroscopy, and attosecond science in water.

Researchers at the Institute for Molecular Science (NINS, Japan) and SOKENDAI have discovered a new optical principle that enables dramatically stronger light generation in water, achieving a 1,000-fold enhancement in broadband white-light output compared to conventional methods.

The team used non-harmonic two-color femtosecond laser excitation, where the two laser wavelengths do not share an integer frequency ratio. While harmonic combinations (such as fundamental and second-harmonic light) are widely employed in nonlinear optics, this is the first demonstration that non-harmonic excitation in water can unlock a powerful regime of light-matter interaction.