Design And Synthesis Of New Diarylethenes And Their Applications To High-Density Optical Storage

It is very necessary and urgent for high-density optical storage technique to develop new photon-mode and rewritable recording materials, and photochromic diarylethene is one of the most promising materials. Recently, diarylethenes have received much attention for their potential applications in optical storage because of their good thermal stability of both isomers, high sensitivity, fatigue resistance and rapid response of different wavelength laser. In present dissertation, sixteen diarylethene compounds were synthesized, and thirteen of them were synthesized for the first time. These compounds have shown good thermal stability (PDT(200(C), remarkable fatigue resistance (repeatable cycle numbers more than 103 times), high cyclization quantum ((max=92%) and refractive index modulated amplitude ((n=10-3~10-2). With new experimental method, it was first discovered allomorphism of photochromic diarylethene DT-3 and this phenomenon could be repeated. Its two kinds of single crystals have different photochromism and two-photon fluorescence effect in crystalline phase. In addition, solvent effect and photochemical reaction kinetics of diarylethene were investigated. Diarylethene showed positive solvent effect which the maximum wavelength is increased with the increasing of solvent polarity. When the intensity of the irradiation light is constant, the cyclization and the cyclorevsion reaction belonged to zero order reaction and first order reaction, respectively.The second part of the dissertation we carried out a series of high-density optical storage tests on the sample discs using diarylethenes as the recording media, such as multi-wavelength, multi-step optical storage, holographic optical storage and near-field optical storage, and so on. The recorded regions appearing as faded dotsindicated that the recorded process based on these photochromic diarylethene was photon-mode recording. The creationary achievements included that we had first accomplished successfully two-wavelength and four-step optical recording on optical disc, three-wavelength and eight-step optical storage on PMMA film and multiplexing holographic grating, holographic images and holographic data storage on thin films whose thickness were less than 10 (m. Using high sensitive diarylethenes as near-field recording media, we achieved near-field recorded dots with ~1 (m size.The writing and readout characteristic of several diarylethenes was studied in the end of the dissertation. The result showed that recording time was decreased with the increasing of cycloreversion sensitivity (((C-O), cycloreversion reaction rate constant(kC-O), recording power(P) and laser wavelength((), respectively. A theoretical recording equation was built up based on the recording kinetics, and the result was consistent well with experimental data. Based on these results, a very simple and feasible non-destructive readout method was proposed and validated. Using diarylethene with very high cyclization quantum and very low cycloreversion quantum as recording materials, non-destructive readout could be realized when the signal was recorded by higher power on the left side of the (max and read out by super-low power. Despite losing part intensity of recorded signal, the method has much practical value. Using this method, the reflectivity difference between recorded dots and unrecorded regions kept 25% constantly after readout more than 2000 times under experimental condition.