Self-Focusing Effect of an Electromagnetic Wave under Various Nonlinearities

Abstract

A short pulse laser beam suffers self-pulse distortion due to combined effects of nonlinearity induced self-focusing and dispersion. Nonlinearity arises due to relativistic mass variation and ponderomotive force. As the beam propagates through plasma, beam width parameter decreases, so intensity of the beam increases. Self focusing of the beam takes place. As time passes, decrease in  is smaller and smaller, broadening of pulse takes place.