Abstract

The Raman interaction contributes about 18% of the nonlinear refractive index of silica optical fibers. By numerical simulation we previously demonstrated that this Raman contribution to the nonlinear refractive index is substantially reduced when the optical pulse width is less than the molecular resonance period.[1] A surprising result of those simulations was that the Raman contribution to the nonlinear index was actually negative for pulse widths less than 30 fsec. Here we show that the negative contribution can be traced to the time delay inherent in the Raman response.

© 1991 Optical Society of America