Steady-state parametric amplification of spreading light pulses under conditions of group velocity mismatch

A theoretical investigation is made of parametric amplification of light pulses in nonlinear crystals under conditions of group velocity mismatch and dispersion spreading. It is shown that dispersion spreading has a strong influence on the amplification. As the role of such spreading increases, the saturation of the gain due to the group velocity mismatch gradually disappears and a steady-state amplification regime is established when the shape of the envelope, and the duration and position of the peak of a signal pulse are all independent of the length of a crystal, whereas the intensity rises exponentially with the distance.