Self-, cross-, and induced-phase modulations of ultrashort laser pulse propagation

Spectral broadenings of picosecond and femtosecond pulses arising from self-phase modulation, cross-phase modulation, induced-phase modulation, and induced spectral broadening in condensed matter are reviewed. The spectral broadening of the Raman line produced in an optical fiber is compared to the spectral width of the pump-laser line as evidence for cross-phase modulation. Induced-phase modulation of a weak picosecond 527-nm laser pulse in BK-7 glass occurred in the presence of an intense picosecond 1054-nm laser pulse. The induced spectral broadening about a weak nonphase-matched second-harmonic pulse at 527 nm is observed by propagating an intense primary 1054-nm picosecond laser pulse through ZnSe crystals.<>