Abstract

It is well known that in the presence of non-ideal phase matching conditions, the harmonic generation process shows an oscillating energy transfer between the pump and the harmonic beams as a Junction of distance inside the crystal[1]. The oscillation period length is inversely proportional to the phase mismatch. A numerical solution of the coupled wave equations shows that when the nonlinear drive term $\left({\omega }_p^2{d}_{eff}^2{l}^2{I}_p\right)$is high, the period length is also dependent on the pump intensity In certain conditions, a monotonous raising of the pump intensity causes a periodic transfer of energy between the two beams When the doubling crystal is pumped by a pulsed laser, there should be a change in the temporal profile of the frequency doubled beam since the pulse intensity is temporally dependent. With a multi-longitudinal mode (MLM) laser this phenomenon is smeared out because each mode has a different phase mismatch Similarly, the diffraction of the beam and the spatial intensity dependence contribute to the smear and the effect cannot be observed.

© 1998 IEEE