Effect of molecular weight of PEG polymer matrix on the diffraction efficiency of Methyl Orange holographic media

Recording media for diffraction gratings formation based on polymer films of polyethylene glycol doped with the photoisomerisable azo-dye Methyl Orange have been developed. Holographic recording of the plane wave front for parallel and orthogonal orientation of polarization vectors of light beams have been performed at room temperature. In order to optimize the recording conditions and obtain high-efficient polarization holographic gratings, in the present work we study the dependence the average molecular weight of polymer matrix and solvent system for thin layers formation on the diffraction efficiency. Five PEG polymers were used as host for azo-dye incorporation −1500, 4000, 6000, 10,000 and 40,000, and two solvent systems, EtOH–H2O and THF-H2O, were examined to investigate film-forming properties. It was concluded, that structure of films as well as diffraction efficiency value and curves character strongly depend on PEG molecular weight.