Relativistic second-harmonic generation and conversion in a weakly magnetized plasma

Relativistic second-harmonic generation with ultrahigh intensity laser puls es in a weakly magnetized plasma is analyzed. Both ordinary mode conversion to second-harmonic extraordinary mode and extraordinary mode conversion to second-harmonic extraordinary mode are considered. Extraordinary mode conv ersion turns out to be more efficient, and a new frequency doubling scheme based on a tapered magnetic wiggler is identified, described, and analyzed. The important issues of phase matching, pump depletion, and relativistic t apering are addressed and solved. Both permanent magnet and laser-driven wi gglers are considered. The interaction of multi-terawatt laser pulses with a magnetized plasma appears to provide an efficient scheme to generate shor t wavelengths. (C) 2000 American Institute of Physics. [S1070-664X(00)01503 -2].