Optical breakdown threshold in the electron-thermal model of defect generation

An investigation is made of the conditions for the nucleation of optical breakdown in transparent material when recombination-stimulated defect-formation reactions occur in it. It is shown that a positive feedback between the conduction electron concentration and point defects activates defect formation even if the medium is not heated. Under real conditions, where heating of the medium by the light is important, lowering of the activation barrier by thermal defect generation aided by conduction electrons results in optical breakdown of the medium at light intensities much lower than predicted in the classical “semiconductor” or “thermochemical” models of thermal breakdown. The analysis confirms that optical breakdown of transparent condensed media is due to electron-aided defect formation reactions over a broad range of illumination conditions. Zh. Tekh. Fiz. 67, 48–53 (May 1997)