Abstract
The state of the art of investigations on filamentation of a high-power femtosecond laser radiation in transparent media is reviewed. The physical picture of this phenomenon is presented and its relation to the fundamental concepts of nonlinear optics and practical applications is demonstrated. Experimental and theoretical methods are briefly considered and laser radiation parameters in the case of filamentation are given. The review can be of interest both for specialists and researches wanting to become familiar with a new, rapidly developing direction in laser physics.