Laser beam propagation in opaque liquids

We experimentally studied the transmission of the Er3+:YAG laser radiation (lambda = 2.94 mum) by strongly absorbing liquids in the mode of free running. The radiation was shown to pass through liquids due to the development of a channel, produced by the laser pulse itself. The transmittances of water, ethanol, and glycerin were studied depending on the laser pulse energy and liquid layer thickness. It was also shown that in the case of oblique incidence of the laser beam, the channel propagates in liquid, slightly deflecting from the beam axis, which is caused by nearly equal refractive indices of air and vapor in the channel. It was found that the beam-liquid interaction is accompanied by a liquid jet directed outwards from its free surface.