Development of Optical Recording System Based on the Local-Field Control

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The optical recording involving the organic dyes is usually based on the spectral change of the dye molecule itself, e.g., photochromism under photo-isomerization. Therefore, the design and synthesis of the dye molecule is of prime importance which could be a hard task. The purpose of the current study is to understand the effect of the local field on the spectrum of a dye molecule and use it for the opptical recording instead. The project is devided into two parts ; one for understanding the local field both experimentally and theoretically and two for demonstrating the effect.1.Sample Preparation : The Langmuir-Blodgett (LB) techniques are mainly used along with the vacuum deposition. A novel LB method without using a spreading solvent has been developed for the indissoluble molecules.2.Local-Field Measurement : The second-harmonic generation (SHG) dfficiency is used to evaluate the local-field contribution to the dye spectrum. The electroabsorption is measured to estimate the local-field factor in gerroelectric polymers.3.Theory : A simple molecular layr model is used to interprete the experimental data in Sec.2.The J-aggregate of dyes has been taken as a model system with the extremely strong local field. The successful reproduction of the absorption, emission, and the resonance Rayleigh scattering spectra shows that our model is realistic.4.Demonstration : Layred structures of ferroelectric polymers and dyes are fabricated using the LB technique. The absorption change of a few % driven by the remanent field can be seasily observed.