Parametric Interactions in Highly Purified Water in Intense Optical Radiation Field: Degassing Effect

Excitation of optical breakdown and four-photon parametric processes in water in a pump field at a wavelength of 1.064 μm with pulse duration of 20 ps was experimentally studied. It was shown that degassing and helium washing of a water sample result in optical breakdown suppression; in this case, the processes of the four-photon parametric interaction are excited most efficiently. This effect is explained by the fact that pump self-focusing in water degassed and washed by helium is regular under given experimental conditions.