Rigorous Bragg condition or volume holographic gratings with anisotropic distortion

Volume holograms have Bragg selectivity because of the volume effect and are used for holographic data storage (HDS), which represents next-generation optical storage. High capacity can be realized in HDS because multiple holograms recorded within the same volume can be retrieved selectively using Bragg selectivity by varying the readout conditions. However, it is inhibited to retrieve holograms via the holographic grating distortion that results from volume or refractive index changes of the medium. We therefore derived the rigorous Bragg matching condition when anisotropic distortion occurred in-plane and the thickness direction of the holographic grating. We also evaluated the effects of readout compensation with angle and wavelength adjustments based on the derived Bragg matching condition using numerical analysis, and the condition's effectiveness was clarified. (C) 2018 Optical Society of America