We synthesized the polyesters containing azobenzene units in the side chain for data storage materials. The structurally similar polyesters, DR-Est-1, DR-Est-2 and DR-Est-3 were synthesized to compare the optical properties of polyesters with different structure from dihalide in the main chain. The diffraction efficiencies of films were measured as a function of the reaction time. Typically, the diffraction efficiency of the DR-Est-3 film prepared from 4,4'-biphenyldicarbonyl chloride was observed up to a level of 0.4%.