Thermally induced self-focusing of a laser beam possessing spatial and temporal inhomogeneity

The results are presented of an experimental investigation into the effect of thermally induced nonlinear refraction on the energy distribution in the beam of a neodymium laser operating in the free-lasing regime. It is shown that, as a result of nonlinear conversion, an energy distribution at the focus of a lens which possesses strong spatial and temporal inhomogeneity is converted into a smooth distribution, close to Gaussian. The mechanism for this conversion is discussed in terms of the successive effects on the medium of the radiation in different plane-resonator oscillation modes. It is suggested that this effect can be used in laser materials-processing technology.