<title>Experimental and theoretical research of propagation of the double-circle laser beam in Kerr-medium</title>

Abstract

The filamentary self-focusing and spot-splitting effects and dark band phenomenon are observed during the propagation of double-circle laser beam in Kerr-medium of CS₂. With solving nonlinear Schrodinger equation numerically, the effects of self-focusing and spot-splitting are observed when the input laser beam's power density over 98kw/cm², which is much lower than the single-circle spot laser beam's threshold of self-focusing and spot-splitting, and the split pulses can undergo additional splitting. The filamentary self-focusing is observed in propagation process as the input laser beam's power density over 135kw/cm² as the propagation length over 65cm and it is closely connected with the spatial splitting. The external and the internal circle's propagation characteristics on intensity, radius and focus are contrasted.