Physics Commons^™

Compression Of Laser Radiation In Plasmas Using Electromagnetic Cascading, Serguei Y. Kalmykov, Gennady Shvets

Serge Youri Kalmykov

Compressing high-power laser beams in plasmas via generation of a coherent cascade of electromagnetic sidebands is described. The technique requires two copropagating beams detuned by a near-resonant frequency, \Omega < \omega_{p}. The ponderomotive force of the laser beat wave drives an electron plasma wave which modifies the refractive index of plasma so as to produce a periodic phase modulation of the laser field with the beat period t_b = 2\pi/\Omega. A train of chirped laser beat notes (each of duration t_b) is thus created. The group velocity dispersion of radiation in plasma can then compress each beat note to a few-laser-cycle duration. As a result, a train of sharp electromagnetic spikes separated in time by t_b is formed. Depending on the plasma and laser parameters, chirping and compression can be implemented either concurrently in the same plasma or sequentially in different plasmas.