Nonlinear spatial dynamics of double phase conjugation in photorefractive crystals and holographic dynamics of photopolymerization

• Main Author: Engin, Doruk
• Format: Others
• Language: en
• Published: 1998
• Online Access: https://thesis.library.caltech.edu/303/1/Engin_d_1998.pdf; Engin, Doruk (1998) Nonlinear spatial dynamics of double phase conjugation in photorefractive crystals and holographic dynamics of photopolymerization. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/78gp-sz41. https://resolver.caltech.edu/CaltechETD:etd-01232008-110449 <https://resolver.caltech.edu/CaltechETD:etd-01232008-110449>

This thesis explores spatial nonlinear optical effects in photorefractive crystals and photopolymers. In these materials upon exposure with spatially varying light, large refractive index changes occur. In the first part of the thesis Double Phase Conjugation in photorefractive crystals is studied both theoretically and experimentally. Various processes effecting the conjugation fidelity, such as fanning are quantified through a coupled multiple mode model which is an extension of the coupled mode theory. Predictions of the model such as phase conjugation is confirmed experimentally. Critical slowing down near the threshold is also predicted and experimentally confirmed. Lastly the amplitude equation formalism is carried out for the wave mixing phenomenon. This approach unifies the optical phenomenon with a large class of other physical phenomena referred to as pattern formation outside of equilibrium. Through this formalism the instability is identified as a convective instability and the possibility of a transition to absolute instability is studied. In the second part of the thesis, photopolymerization dynamics is studied with holography. A theoretical model is developed for the holographic configuration starting from a standard chain polymerization model. A holographic characterization method is developed. The method is especially powerful in measuring diffusion constants. Various multifunctional polymers is characterized using the novel technique.