Features of focusing of laser radiation in supercritical CO$_2$ media

The features of the formation of point microstructures by femtosecond laser radiation on the surface and in the subsurface layer of nanoporous quartz glasses impregnated with silver precursor molecules under air and water conditions are considered. The role of water in changing the morphology of the resulting microstructures based on silver nanoparticles has been demonstrated. In contrast to crater structures formed in the air, in an aquatic environment, convex conical microstructures up to 2 $\mu$m in height appear in the center of the laser irradiation area. Models are proposed to explain the obtained effects.