Holographic optical data storage of 2000 images by photochemical hole burning

Abstract

In addition to its importance for the optical spectroscopy of solids, photochemical spectral hole burning (PSHB) has attracted great interest due to its potential use in high density optical data storage [1]. By encoding information as a function of frequency an enormous increase in storage is possible compared to conventional optical storage materials. The most optimistic estimates predict an increase given by the ratio of the inhomogeneous linewidth to the homogeneous linewidth of the optical transition responsible for hole burning. Until now, however, there have been relatively few investigations of the practical limitations to storing a large number of spectral holes [2,3]. We describe here a recent experiment in which 2000 grayscale images were successfully recorded as holograms in the PSHB material chlorin in polyvinylbutyral. In holographic spectral hole burning the relative phase of the interfering light waves used to prepare the hologram has a strong influence on diffraction properties and, hence, on crosstalk between adjacent holograms [4]. By controlling the phase and frequency during burning in a novel manner, we have minimized crosstalk between the stored images.