Abstract :
In an optical parametric generation of a femtosecond pulse for a biaxial crystal, the interaction of three waves can be used as a model of noncollinear phase matching in which the group velocities of the interacting pulses are suitably linked to each other. For satisfaction of group-velocity matching, the tunable parametric generation of femtosecond pulses must use noncollinear phase matching. We consider three conditions of group-velocity matching for femtosecond pulses. Signal and idler pulses can be obtained when the coupled-wave equations, including the groupvelocity mismatch and group-velocity dispersion effects, are solved. A Fourier method is an effective method for solving the equations, and from the solution of the equations the relation between duration of output pulses and wavelengths can be obtained. In a comparison of collinear and noncollinear matches, when the latter is group-velocity matched, the duration of its outpulses are smaller, and the outpulses can be continually tuned from the visible to the mid-infrared.
