Photorefractive materials have many potential applications, including dynamic holographic storage and image processing. Recently, the new class of amorphous organic photorefractive materials has emerged, offering wide structural flexibility, easy processability, and low cost at very high performance levels. Progress in this field has led to absorption-limited complete diffraction for the readout of a hologram stored in materials of only 100-150 mm thickness and to extremely large net gain coefficients of more than 200 cm-1  compared to 40-50 cm-1 in the best inorganic photorefractive crystals known to date. These excellent properties occur in materials with low glass transition temperatures and result from refractive index modulations as large as Dn ª 10-2, mostly originating from a Kerr-type orientational birefringence rather than the electro-optic effect as in traditional photorefractive crystals. The materials can be adjusted for photorefractivity over the entire visible spectrum and in the near infrared. The sensitivity is excellent enabling the use of low-power laser sources, such as HeNe laser or laser diodes. We will present a series of PR guest/host materials based on poly(N-vinylcarbazole) using merocyanine dyes as the electrooptic chromophores . After optimization we obtained a composite with excellent stability and an one order of magnitude larger index modulation amplitude at 790 nm compared with the reference composite DMNPAA:PVK:ECZ:TNF measured under identical conditions . Furthermore, we have discovered that under certain conditions the performance of the devices can be asymmetric with respect to the applied electric field direction . For one field direction, light is coupled into the polymer layer and can be detected on the side of the devices. For the other, the originally Gaussian-shaped writing beams show a shoulder or even split into two. The strength of the asymmetry depends on the diameter of the beams writing the hologram. We demonstrate that this effect is due to beam fanning. Finally, we demonstrate the existence of six independent PR gratings, which compete inside the organic PR devices. This results from the internal reflection of the holographic beams on the internal polymer/ITO interface . 1. K. Meerholz, B. Volodin, Sandalphon, B. Kippelen, N. Peyghambarian, Nature 371, 497 (1994). 2. F. W¸rthner, R. Wortmann, R. Matschiner, K. Lukaszuk, K. Meerholz, R. Bittner, Angew. Chem. Int. Ed. Engl. 36, 2765 (1997). 3. K. Meerholz, Y. De Nardin, R. Bittner, F. W¸rthner, R. Wortmann, Appl. Phys. Lett., 73, 4 (1998). 4. K. Meerholz, R. Bittner, Y. De Nardin, Opt. Commum., 150, 205 (1998). 5. Meerholz, R. Bittner, E. Mecher, Y. De Nardin, J. Opt. Soc. Am. B, 15, 2114 (1998).