Hannover 2003 – wissenschaftliches Programm
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SYNO: Nichtlineare und transversale Optik
SYNO I: HV I
SYNO I.1: Hauptvortrag
Montag, 24. März 2003, 14:00–14:30, F142
Self-organized superlattices – an example for strongly nonlinear structures in a pattern-forming optical system — •Th. Ackemann, M. Große-Westhoff, M. Pesch, and W. Lange — Institut für Angewandte Physik, Westfälische Wilhelms-Universität Münster
Transverse nonlinear optics represents a rapidly growing field due to the variety of self-organization phenomena accessible in spatially extended optical systems. Recent interest concerns the properties of large-amplitude, i.e. strongly nonlinear, structures which arise far beyond threshold of pattern formation by a secondary bifurcation from a primary patterned state.
After a brief review of basics of optical pattern formation, examples of strongly nonlinear patterns are discussed in an archetypical system: A thin sample of a nonlinear optical medium and a single plane mirror providing feedback. In the experiment sodium vapour driven in the vicinity of the sodium D1-resonance is utilized [1].
In a suitable configuration, the hexagonal patterns emerging at threshold become unstable versus quasiperiodic patterns [1] and superlattice patterns, if the input power is increased far beyond threshold. The superlattice patterns are based on reciprocal lattices of either hexagonal or square symmetry. Possible mechanisms for their stabilization are discussed in terms of phase-sensitive four-wave-mixing. Differences and similarities to superlattice patterns known in hydrodynamical and in reaction-diffusion systems are elucidated.
[1] T. Ackemann and W. Lange. Appl. Phys. B 72, 21 (2001)