Controlled phase mismatch in sectioned dynamic holographic moiré-like patterns

In the present work attention is given to the physical description of phase mismatch produced in sectioned holographic moiré-like patterns. It is obtained by the controlled superposition of two sinusoidal phase gratings made by dynamic holographic process. In the writing stage of the photorefractive hologram, a two wave mixing (2WM) process, half of the transverse section of the reference beam has the optical path increased, producing this way the sectioned moiré-like pattern. The sinusoidal phase gratings, with slightly different pitches, are dynamically generated by photorefraction in a Bi12TiO20 (BTO) crystal sample. This photorefractive holographic medium was used in an anisotropic self-diffraction configuration and in diffusion as the only recording mechanism.