“…For instance, in a singly resonant OPO cavity the Ginzburg-Landau description is appropriate [12,13] whereas in a doubly resonant OPO cavity the Swift-Hohenberg description is valid [12,13]. Observed OPE/OPO solutions include localized pulse-like solutions [5,19,20], domain-walls (fronts) [4,14,[20][21][22], labyrinths [22] oscillatory (Hopf) structures [23], and such patterns as rolls, hexagons and zig-zags [10].…”