The role of traps in the restoration of faded holographic images in Bi12SiO20

Faded holographic images stored in Bi12SiO20 can be restored to levels suitable for signal processing by means of applied light and electric fields. The process is relatively insensitive to the wavelength of the restoring radiation. A single beam incident at any angle will restore the image. A model has been developed that satisfactorily accounts for all the observed features of the phenomena. The model assumes differential depopulation of very long-lived electron and hole traps. Finally, we suggest a procedure that may permit useful storage of holographic images for long intervals of time, without resorting to the restoration process.