The generation and transmission characteristics of optical pulses with nonlinear chirp are analytically studied. When we compare our results, assuming a Gaussian pulse with a quadratic chirp at the input of a dispersive fiber, with results obtained with the Gaussian model with linear chirp, the position of maximum narrowing is modified and the velocity of broadening of the pulse envelope during the propagation is reduced. Our analytical results are in good agreement with numerical simulation of semiconductor laser pulses. The model could be useful, for example, for dispersion compensation analysis.