Optical pattern formation far beyond threshold

Abstract

Optical pattern formation is studied far beyond threshold in a single-mirror feedback scheme using sodium vapor as the nonlinear medium. Patterns with twelve fundamental wave vectors arise form hexagons in a secondary bifurcation. Besides irregular patterns, quasi patterns and superlattices are obtained. Even after a tertiary bifurcation the patterns remain stationary. Fourier filtering experiments show that the harmonics of the fundamental wave vectors are essential for the stability of the secondary and tertiary patterns. A novel Fourier filtering technique is used for a measurement of the neutral stability curve and proves experimentally the existence of multiple instability regions existing due to the periodicity of the Talbot effect.