We introduce a new physical model for description of thin polarization holograms recorded and reconstructed with complex reference beams. Next we apply this model for two fundamentally different arrangements supposed to be used in a data storage system based on phase coded thin polarization holograms. On the basis of the model, we construct some computer programs for simulation of the storage system and optimization of the phase codes. We investigate the feasibility of multiplexed and security encrypted data storage in the form of thin polarization holograms based on the phase encoding method.