Self diffraction holographic techniques for investigation of photosensitive materials

摘要

Holographic techniques are powerful tools to study photosensitive materials due to the high sensitivity of diffraction measurement and the ability to detect dynamic gratings. The self diffraction technique consists in to project an interference fringe pattern into the photosensitive material and to measure, in real time, the self-diffraction of the interfering beams, at the grating generated in the photosensitive material. Besides the higher sensitivity, such measurement allows to measure simultaneously and separately the phase and the amplitude grating contributions, as well as thin or thick gratings. In order to demonstrate potentiality of this technique we measured the kinetic constant of the photo-reaction in positive photoresists (AZ types) and negative SU-8 photoresist, as well as the maximum values of the refractive index and of the absorption coefficient modulations induced in these materials at different wavelengths of exposure. The same measurements were performed in SB based chalcogenide glasses in order to evaluate the potential of such materials to be used as optical data storage devices.