Frequency chirps and spectra of optical pulses propagating in optical fibers with cubic-quintic nonlinearity

The aim of the paper is to study the effect of the quintic nonlinearity of an optical fiber on the propagation of optical pulses.Utilizing the cubic-quintic nonlinear Schrdinger equation in which the dispersion of optical fibers is neglected,the nonlinear phase shifts and frequency chirps of super-Gaussian optical pulses are calculated and investigated analytically.The power spectra of optical pulses are numerically simulated as well.The results show that the positive quintic nonlinear refractive index makes the nonlinear phase shifts and the maximum frequency chirps of optical pulses larger,the spectral width of unchirped optical pulses wider and the number of spectral peaks more than those of cubic nonlinear refractive index.The influence of initial chirps of Gaussian optical pulses on the spectra is similar to that of cubic nonlinear refractive index.In case of the negative quintic nonlinear refractive index,the nonlinear phase shifts and frequency chirps take on new characteristics.The negative quintic nonlinear refractive index also makes the width of unchirped optical pulses narrower and the number of spectral peaks less.