Near Ultraviolet Holographic Storage Based On The Modulation Of Merocyanine Aggregates

In the information era of rapid development of science and technology,stability and integration are the pursued goals for developing photonic devices.Information transport,display and storage,have been realized in organic photochromic materials,which provide the possibility of their application in integrate photonics.Spirooxazine?SO?is a typical organic photochromic medium,which has advantages of low-cost,flexibility,large-area film-forming,as well as the controlled physical parameters of absorption coefficient,refractive index and dielectric constant,which has attracted considerable interest in these characteristics.This thesis gives a detailed description of the photochromic properties,photo-anisotropy and holographic storage dynamics were both investigated with different polarization states and power densities in organic photochromic films under near-UV irradiation.Details are as follows:?1?In the thesis,SO/PMMA and SO/SiO₂ films were prepared by drop-coating and spin-coating,respectively.The time-dependence of absorbance and fluorescence intensities on different matrices were analyzed.?2?The study focused on anisotropy related to merocyanine aggregates(MC_agg).The real-time dynamic process of photo-anisotropy in SO/PMMA films was recorded by the pump-probe method.By changing the power densities of the pump light,theoretical model was accurately built up.Kinetics parameters were obtained by fitting to experimental results.The process of the photo-anisotropy was explained.The fitting results suggested that the photo-anisotropy was mainly affected by the Angular Hole Burning of merocyanine monomer(MC_mono).Meanwhile,the photo-anisotropy was also influenced significantly by MC_agg with H-aggregates structure,which only generates a rather low anisotropic growth.However,MC_monoono and MC_agg were formed sequentially with the help of long-time excitation of near-UV light.?3?Near ultraviolet?403.4 nm?holographic storage based on the modulation of merocyanine aggregates was studied in detail.The investigation was carried out from two aspects:?i?Nonvolatile blue-violet holographic storage.The holographic dynamics were recorded by coherent blue-violet lights with different polarization and power densities in SO/PMMA films.The theoretical fitting suggested that the holographic process was consisted of one phase grating and two absorption gratings.Benefiting from the stability of MC_agg,the long-term hologram memory,fluorescence emission and stable surface relief structure were all realized in the photochromic films.?ii?The erasable holographic storage and fatigue-resistance properties under blue-violet irradiation were studied in SO/SiO₂ films.The formation of MC_agg was inhibited in the SiO₂ matrix.As a result,the erasability of information was enhanced,and the transformation between molecules was reduced to improve the anti-fatigue properties of SO-based films.The work in this thesis provides a feasible research approach for the modulated integrated photonic devices.