High intensity focusing of laser pulses using a short plasma channel lens

Plasma channels have been used to guide intense laser pulses over distances of many Rayleigh lengths. This paper investigates the possibility of using a short plasma channel to provide focusing or control of the spot size of a laser pulse at intensities far above the usual damage limits of conventional optical elements. Analytical models for the focal length and focused spot size of a single plasma channel lens and a nonconverging laser pulse are presented, and results are compared with the two-dimensional simulation code LEM [J. Krall , Phys. Rev. E 48, 2157 (1993)]. Several advanced thin lens configurations, including multiple lens transport systems, and both focusing and defocusing lenses for externally focused converging laser pulses are also analyzed. Experimental techniques for producing appropriate plasma profiles are reviewed, and evidence for plasma channel focusing in a capillary discharge guiding experiment is analyzed. Thick "overmoded" lenses offer a possible alternative if there are experimental difficulties in producing sufficiently thin plasma channels. A variety of potential applications exist for the various proposed lens configurations. (C) 2002 American Institute of Physics.