MODELLING OF THE DIRECT LASER-INDUCED OPTICAL BREAKDOWN IN SOLID

Abstract

The problem of modeling the laser-induced optical breakdown is represented as creation universal method for all media – from gases to solid. It is the first attempt of observation this problem in main details in whole. Level of complexity of this problem is shown. From physical-chemical point of point of view the optical breakdown is the regime of fool breakage of all chemical bonds in irradiated matter in zone of laser irradiation. In this case we can determine the threshold of breakdown of irradiated matters with help methods of Relaxed Optics. This regime may be received with help three ways. First is thermal. In this case the basic relaxation of first order processes of optical excitation are thermal. Examples of these process are regimes by continuous and millisecond laser irradiation of matter. Second is plasma. In this case the main role of the optical breakdown has process of formation “collective” electromagnetic (electron-ionic) process. The examples of this process are the irradiation in the millisecond or nanosecond regimes of irradiation. In this case laser-induced plasma radiated continuum optical spectra in all direction (star effect). Third is directing optical. In this case we have direct multiphotonic ionization and these processes have oriental nature. The second order irradiation has Cherenkov nature. The experimental data were received for nanosecond, picosecond and femtosecond regimes of irradiation. This differentiation is connected with various nature of relaxation of first-order optical excitations. The comparative analysis of three types modeling is represented. We show that third direct laser-induced breakdown is companioned by the nonlinear optical transformation of initial radiation (diffraction stratification, Cherenkov radiation and interference of its radiation). The chain of corresponding models for various media are represented and discussed. Thus we show that large value for the laser-induced optical breakdown has nonlinear optical processes and therefore this process has complex chain nature this fact must be included for the modeling these processes.