The holographic storage of information is based on the interference of two waves: the reference wave and the object wave, the latter is generated by using a spatial light modulator, and in the case of applications of data storage this corresponds to a binary pattern of one and zeros. The interference pattern is recorded in a photosensitive medium (photopolymers, photographic emulsions, photorefractive, etc.), so that when illuminated by the reference wave the object wave is reproduced. In order to properly investigate the characteristics of the generated hologram it is necessary to adequately study the interaction of electromagnetic radiation with the recording medium. In this work we develop a completely vectorial formalism for solving the Helmholtz equation that allows investigation of electromagnetic dispersion in dielectric media in which the refractive index varies spatially. The method is based on the technique of Green's tensor and allows to correctly simulate the behavior of a volume hologram. This method is compared with the method of discrete dipoles and a formalism based on the first Born approximation to determine the intensity of light scattered by a volume hologram.