Nonresonant real-time polarization holographic storage in azo-dye-doped polymer film

We report experimental results of the nonresonant third-order nonlinear properties of an acceptor-donor azo dye doped in polymethyl methacrylate (PMMA) thin films by degenerate four-wave mixing with a He-Ne laser, which have appreciable nonresonant third-order nonlinearity, (chi) (3) being approximately 4 X 10-4 esu. The OPC signal has strong sensitivity with the polarization of the three incident beams, and the self- refracted phase conjugation by the coupled two counter-propagation beams was studied. In conclusion, nonresonant third-order nonlinear mechanism is demonstrated to be a result of photoinduced birefringence of the azo molecules. The real-time polarization storage properties of the azo dye were used in the interferometry to measure the shape variation of the object.