Compression of the coherence time of incoherent signals to a few femtoseconds

We compute in the femtosecond regime the coherence time compression ratio and the corresponding spectral broadening owing to self-phase modulation of an incoherent signal propagating in an optical fiber. We incorporate in our differential equation the terms responsible for group-velocity dispersion, higher-order dispersion terms self-steepening, and induced Raman scattering. Using typical fiber parameters, we show that it is possible to compress the coherence time of an incoherent signal to few femtoseconds.