ABSTRACT
This chapter discusses some of the patterns, defects and turbulent behaviour recently observed in passive nonlinear optical systems. Spontaneous optical patterns are not only of intrinsic interest, but also in relation to similar phenomena in other areas of science. The chapter argues that the spatial complexity evidenced by pattern formation can be harnessed for application to information processing, for example as all-optical memories. Self-exciting oscillators, and optical chaos or turbulence are other qualitatively new phenomena arising through optical nonlinearity. The chapter gives some examples of pattern formation, spatial instability and complex dynamics in optical cavities. It summarises recent numerical investigations of the two–transverse dimensional equation describing the mean-field model of optical bistability, showing that roll–patterns form at threshold spontaneously but are unstable to hexagon formation. Hexagons typically arise from a quadratic nonlinear coupling in a system with an unstable transverse wave vector.
