Parametric interaction in deeply purified water in a high-power optical radiation field. Degassing effect

The excitation of optical breakdown and four-photon parametric processes in water is studied experimentally in a pump field with a wavelength of 1.064 μm and a pulse duration of 20 ns. It is shown that degassing and helium-flushing of the water sample suppress the optical breakdown. In this case, four-photon parametric interaction processes are excited most efficiently. This result is explained by the fact that under the given experimental conditions, self-focusing of pumping is regular in degassed and helium-flushed water.