Abstract

Dynamic holograms in bismuth silicon oxide (Bi₁₂SiO₂₀ or BSO) crystals exhibit pronounced optical polarization effects due to concomitant natural optical activity and electric-field-induced linear birefringence. Detailed computer studies of this polarization behavior have clarified the optimum configurations for maximizing the light diffraction efficiency and signal-to-noise ratio of recorded holograms. Experimental parameters that are most readily manipulated include the polarization state of the input readout light beam, the magnitude of the applied bias electric field after the grating has been written, and the angular alignment of the readout beam with respect to the grating. Bismuth silicon oxide exhibits very interesting polarization and diffraction efficiency characteristics for off- Bragg angles.^1,2 For sufficiently thick crystals, the angular alignment sensitivity curve consists of multiple peaks. For thinner crystals, these multiple peaks are unresolved, but their impact on optimum diffraction configuration is nevertheless quite striking. For the {K_G⊥ [001]) BSO crystal orientation, an increase in diffraction efficiency of up to a factor of 2 can be realized by using circularly polarized light rather than linearly polarized light and by realigning the BSO crystal for maximum diffraction. These results hold even in the case of thin crystals for which the multiple diffraction peak structure is inadequately resolved.

© 1985 Optical Society of America