In this paper we have retrieved the nonlinear-index coefficient based on the self-phase modulation which is resulted from a high-power laser pulses propagating in a third-order nonlinear optical material. Using the finite-difference time-domain method, the spectrum analyses have been performed with the optical pulses with different peak-powers propagating through the nonlinear optical materials with different lengths. The nonlinear-index coefficients were obtained by using the numbers of the spectrum peaks, and how to improve the accuracy has been discussed.
Effects of Nonlinear Chirp on the Self-Phase Modulation of Ultrashort Optical Pulses