We report our findings from a detailed series of three-dimensional simulations of degenerate counterpropagating beam instabilities in a nonlinear Kerr medium. These simulations show the formation of far field intensity patterns with both radial and hexagonal symmetries in agreement with recent experiments. Moreover, we suggest that the ring patterns which are characteristic of degenerate conical emission are transient phenomena which are always replaced by hexagons for long enough times, at least close to the plane-wave threshold. For misaligned input beams we observe the formation of a stabel point defect, a penta-hepta pair, in the hexagonal pattern.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering