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Q: Quantenoptik und Photonik
Q 71: Transversale nichtlineare Optik
Q 71.3: Talk
Wednesday, March 9, 2005, 15:30–15:45, HU 1070
Secondary modulation instability of partially coherent beams in anisotropic media — •Björn Gütlich1, Cornelia Denz1, Thomas König1, Kristian Motzek2, and Friedemann Kaiser2 — 1Institute for Applied Physics, WWU Münster, Corrensstraße 2, 48149 Münster — 2Institute for Applied Physics, TU Darmstadt, Hochschulstraße 4a, 64289 Darmstadt
Induced by noise uniform optical beams break up into filaments in the presence of a nonlinearity. Initially such modulation instability was only considered to be possible with coherent beams. Recent experiments show that in noninstantaneous media also partially coherent beams exhibit a modulation instability. Incoherent modulation instability attracts interest due to the co-existence with optical solitons, which promise interesting features for application in optical information processing. In anisotropic media, such as photo-refractive crystals, used in our experiment, the beam break up does not occur isotropically in both transversal directions, but occurs successively from stripes at a first threshold into two dimensional filaments at a second threshold. We investigate experimentally and numerically the dependence of first and second threshold of the modulation instability on the coherence properties of the beam.