Description:
Theoretical and experimental study of linear propagation of femtosecond laser pulses through a birefringent dispersive medium is presented. Ordinary and extraordinary components of the pulse propagate through the crystal with different group velocities and they acquire different chirp. We show that, under proper circumstances, the output pulse shows significant time dependent change of polarization. The effect can be used to shape such pulses yielding, for example, a series of equally spaced short pulses.