DYNAMICS OF MULTIPLE 2-WAVE MIXING AND FANNING IN PHOTOREFRACTIVE MATERIALS

We investigate the dynamics of multiple two-wave mixing in photorefrac tive materials. This is the first time to our knowledge that a study o f the dynamics of many pairs of two-wave mixing interactions has taken place. A basic case with three waves undergoing multiple two-wave mix ing is studied numerically. A numerical study is also performed in whi ch many waves are used to model the time development of the fanning ef fect. Comparison of this numerical model with a basic experiment invol ving fanning in the presence of a two-wave mixing interaction is given . A qualitative agreement is exhibited. In addition, it is found that effectively reducing the coupling constant of a two-wave mixing intera ction by the addition of an incoherent background beam can, under cert ain circumstances, significantly reduce the fanning without lowering t he signal level.