Parametric amplification of spreading optical pulses in media with quadratic nonlinearity

A numerical analysis is made of parametric amplification of femtosecond optical pulses in media with a quadratic nonlinearity under conditions of dispersive spreading. Laws governing changes in the envelope and frequency modulation of the pulses being amplified are determined. A detailed study is made of mutual compression of the interacting pulses under conditions of strong interpulse energy exchange. It is shown that these effects can take place in specific nonlinear crystals.