Electrodynamic resonances and instabilities in transparent medium and their role in laser-induced damage

There are considered both linear and nonlinear electrodynamic precesses resulting, in variation of space distribution of electromagnetic-field amplitude and its local increasing. The processes take place near pre-existing and laser-induced bulk defects in optical media as wed as near surfaces. Among linear processes there are considered electromagnetic resonances resulting in great local increasing of field amplitude. The resonances include polaritones, generation of guided modes, evanescent waves and whispering modes. Nonlinear-optical processes together with resonances can result in very effective excitation of eigenmodes. To show important role of the mentioned processes there are considered real examples: 1) formation of light-induced nonlinear optical waveguide induced by high-power near-surface electromagnetic field and generation of its resonant guided modes; 2) amplification of field amplitude near spherical and cylinder microdefects induced by formation of resonant whispering modes. There is considered influence of laser-induced feedbacks between acting electromagnetic field and additions to polarization of both and surrounding medium on dynamics of the processes. It is shown that it can result in field instability of initial field distribution. There are considered specific regularities of developing of laser-induced instabilities in medium without absorption and possible mechanisms of field stabilization. The general regularities are illustrated with estimations and analysis of conditions for realization of the mentioned processes.