https://doi.org/10.1007/s100530050175
Transverse dynamics of optical parametric oscillators in presence of walk-off
1
Laboratoire de Physique des Lasers, Atomes et
Molécules (Laboratoire associé au CNRS.) , Centre d'Études et de Recherches
Lasers et Applications, Université des Sciences et Technologies
de
Lille, 59655 Villeneuve d'Ascq Cedex, France
2
Laboratoire de Mécanique de Lilleb, Université des
Sciences et Technologies de Lille, 59655
Villeneuve d'Ascq Cedex, France
Corresponding author: a majid.taki@univ-lille1.fr
Received:
4
March
1998
Revised:
15
June
1998
Accepted:
23
June
1998
Published online: 15 September 1998
We present a model for non degenerate optical parametric oscillators (OPO) including diffraction and walk-off effects, and report how the transverse beam profile is changed by the walk-off. A complex order-parameter description for the OPO near threshold leads to a two dimensional evolution equation with symmetry breaking stemming from the presence of walk-off. We find that the onset of instability is hastened and that the emerging transverse beam profile propagates in the walk-off direction. This prediction agrees qualitatively with recent experimental results. The convective nature of the instability at the first bifurcation predicts that only the noise-sustained structures may play an important role. The absolute instability observed at larger values of the pump parameter, gives rise to dynamically self-sustained patterns. Numerical simulations are reported to illustrate a possible sequence of convective and absolute instabilities together with the subsequent nonlinear transverse spatio-temporal dynamics.
PACS: 42.65.Yj – Optical parametric oscillators and amplifiers / 42.65.Sf – Optical spatio-temporal dynamics / 47.20.-k – Hydrodynamic stability
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1998