Laser filamentation induced bubbles and their motion in water

Highly extended filaments in aqueous gold nano-particle colloidals

A new regime of filamentation has been discovered in aqueous gold nanoparticle colloidals (AGNC). Different from filamentation in liquids, in this regime, by doping water with gold nanoparticles, there is no observable multiple small-scale filaments, but instead a spatially continuous plasma channel is formed. The length of the filament is more than ten times as compared with that in water. Filamentation in AGNC is characterized by a colorful light channel, with generated supercontinuum ranging from 400 nm to 650 nm which is scattered along a cyan-orange path.

Filamentary plasma grating induced by interference of two femtosecond laser pulses in water

We present direct observation of filamentary plasma grating induced by interference between two noncollinear infrared femtosecond pulses in water by doping with gold nanoparticles. The gold nanoparticles act as scattering media in water and visualize the fine structure of local optical fields of plasma grating. By measuring the variation of local conductivity as laser undergoes filamentation in water, the generated electron density in water is qualitatively studied. Significant enhancement of local electron density is observed at the intersecting region as two laser beams form plasma grating, indicating the breakthrough of clamped intensity of a conventional filament in water.