Cross-phase modulation induced ultrashort pulse train generation from cw light in the normal-dispersion regime of optical fibers

Abstract

A novel technique that leads to the generation of a train of ultrashort optical pulses from cw light in the wavelength regime of normal fiber dispersion is proposed. It consists of copropagating a cw signal with a train of closely spaced pump pulses in an optical fiber where both the signal and the pump experience normal fiber dispersion. As the pump broadens, the part of the signal between neighboring pump pulses becomes negatively chirped owing to pump pulse collision induced cross-phase modulation. Normal group-velocity dispersion then starts to squeeze the signal energy in the negatively chirped region, thus leading to amplitude modulation of the signal and eventually to a pulsed structure. Numerical simulations show that the generated signal pulses can be much shorter than the pump pulses.