Dependence of Holographic Grating Formation upon Interference Pattern Orientation in Bismuth Silicon Oxide

摘要

Bismuth silicon oxide (BSO) is a material which shows good promise for use as a reusable holographic storage medium, with cycle times on the order of milliseconds. When operated without an applied voltage, fringe patterns are weakly recorded through a space charge field in the crystal equally well for all fringe orientations. The fringes are recorded much more strongly in the crystal when a field of 5 to 10 kV/cm is placed across the crystal; however, strength of fringe storage becomes dependent on the orientation of the fringes upon the crystal. Thus, it is necessary to determine how the strength of fringe storage depends upon the fringe angle to fully utilize the advantage of using an applied voltage to enhance crystal performance. A particularly simple hologram is made by interfering two plane waves, producing a sinusoidal interference pattern with parallel fringes. By measuring diffraction efficiencies of thick birefringent phase diffraction gratings formed in BSO by recording a sinusoidal interference pattern for a variety of fringe angles, the effect of fringe orientation upon fringe storage can be determined. This is the approach used in this thesis to analyze the fringe angle dependence of fringe storage in BSO.