Non-Bragg diffraction orders in highly efficient photorefractive polymers

Summary form only given. Photorefractive polymers have improved considerably in recent years. Due to their higher processing capabilities compared with inorganic photorefractive crystals and their high efficiency and sensitivity they appear as promising new materials for photonic applications. Due to high refractive index modulations that can be achieved in DMNPAA:PVK:ECZ:TNF guest/host photorefractive polymers, we recently demonstrated with these polymers a variety of optical applications including holographic storage and dynamic holographic interferometry with low-power laser diodes in a four-wave mixing geometry. In this paper, we demonstrate that the recording of thick phase holograms in these polymers leads not only to very efficient Bragg diffraction but also to strong diffraction into non-Bragg orders. These non-Bragg orders have features drastically different from those of Raman-Nath diffraction orders on thin gratings.