Relativistic-ponderomotive effects on cross-focusing of hollow Gaussian laser beams in plasma

The present work aims to study the influence of relativistic-ponderomotive effects on cross-focusing of two co-propagating high-power hollow Gaussian laser beams [high-power laser beams (HGLBs)] in collisionless plasma. The effective dielectric constant has been derived on account of relativistic-ponderomotive nonlinearity. The phenomenon of cross-focusing for higher-order modes of HGLB is compared for the case when only relativistic nonlinearity is operative in the system and it is seen that the relativistic-ponderomotive effects make the focusing much stronger and relatively faster. The critical curves for various order of HGLB is discussed and compared with the case when only ponderomotive nonlinearity is present and it reveals that in the case of relativistic-ponderomotive case the spot size reduces effectively. The higher-order modes of propagation of HGLB are also found to be governed by the parameter of another propagating HGLB. The present study is useful in determining the propagation dynamics of HGLB.