Controlling transverse-wave interactions in nonlinear optics: generation and interaction of spatiotemporal structures

It is shown that a new type of instability of a light field in a dissipative medium (spatiotemporal instability, which causes the generation of new types of nonlinear light wave) can be observed by controlling the spatial scale and the topology of the transverse interactions of light fields in a medium with cubic nonlinearity. The excitation conditions for optical reverberators, rotating helical waves, and various dissipative structures are experimentally determined. Transformations and interactions of the structures lead to optical turbulence in both space and time. Physical interpretation of these phenomena is based on the parabolic equation for the nonlinear phase shift. It is found that this theoretical model allows one not only to obtain the excitation conditions but to investigate thoroughly such phenomena as hysteresis and nonlinear interactions of structures.