Frequency broadening by self-phase modulation in optical fibers

Abstract

We examine the effects of optical nonlinearities that are due to the intensity-dependent index of refraction in optical fibers. The broadening of the frequency spectrum of an optical pulse will combine with the group-velocity dispersion, increasing the temporal pulse spreading, thereby limiting the information transmission rate. We derive an exact formula for the rms frequency width of a Gaussian input pulse after it undergoes self-phase modulation. This new formula gives good agreement with experimental results.