Relativistic plasma-wave pulse-compression

Summary form only given. With current techniques, using the Kerr nonlinearity of a gas filled hollow fiber together with chirped mirrors, sub-10 fs pulses with a maximum peak intensity of I/spl ap/10/sup 17/ W/cm/sup 2/ can be achieved after tight focusing. It is not possible to extend this pulse compression technique to higher pulse energies because of the onset of fiber damage. However guiding is essential to eliminate transverse pulse distortion and to achieve long interaction distances necessary for pulse compression. Therefore, we propose to use, instead of a hollow waveguide, a plasma-channel which can be preformed or can be generated by self-channeling. The advantage of a plasma channel is that guiding of laser pulses with unlimited pulse energies and peak intensities is possible. Our numerical (1D-PIC) analysis indicates that, similar to the Kerr nonlinearity in optical fibers, the plasma nonlinearity in the channel can be utilized for pulse compression. The spectrum of laser pulses with an initial duration <100 fs is broadened and exhibits a nearly quadratic phase dependence. Compensation of the quadratic phase compresses the pulse by a factor of /spl sim/10 promising the possibility of extending the feasibility of few-cycle laser pulses into the relativistic intensity regime (I>10/sup 18/ W/cm/sup 2/).