M. Taki et al., Order parameter description of walk-off effect on pattern selection in degenerate optical parametric oscillators, PHYS REV E, 61(2), 2000, pp. 2133-2136
Degenerate optical parametric oscillators can exhibit both uniformly transl
ating fronts and nonuniformly translating envelope fronts under the walk-of
f effect. The nonlinear dynamics near threshold is shown to be described by
a real convective Swift-Hohenberg equation, which provides the main charac
teristics of the walk-off effect on pattern selection. The predictions of t
he selected wave vector and the absolute instability threshold are in very
good quantitative agreement with numerical solutions found from the equatio
ns describing the optical parametric oscillator.