| dc.description.abstract | Lithium niobate is one of the widely used photorefractive materials in the field of holography and optical signal processing. However, there is always the effect of light-induced scattering, the “fanning effect”, in lithium niobate crystal under light illumination. The fanning effect is due to the nonlinear photorefractive effect, and it will reduce the signal-to-noise ratio of the storage system. Therefore it is an important issue to investigate the fanning effect in lithium niobate crystal. Based on this idea, in this thesis I discussed the phenomenological characteristics of fanning effect in lithium niobate crystal in different configurations. I also proposed some applications using fanning effect. In studying the characteristics of fanning effect, we investigated the fanning
effect in different crystal orientations, liquids in which the crystal is immersed, light
polarization states, light spot sizes, and light intensities. We found that when the crystal is x-cut, fanning effect always occurs regardless of the polarization state is ordinary or extraordinary. On the other hand, different immersing liquids or light spot sizes do not change the phenomenon of fanning effect. In applying fanning effect, we proposed a novel method to record images in lithium niobate using only object beam. The recording is due to fanning effect, and it can be analyzed using the model of fanning hologram. Using this recording
method, we accomplished gray-level pattern multiplexing. We further demonstrated one-way imaging through dynamic turbid media using this recording method. Our method is, to our knowledge, the simplest one-way imaging method, and it is also the only one that can work on any polarization state of light. Finally, although
incoherent light never induces fanning light, we found it can also induce variation of refractive index of lithium niobate crystal. We also investigated its mechanism, and suggested some applications using the incoherent one beam recording method. | en_US |