Author name:
فيصل صادق ثامر
Supervisor name:
عماد الدين حسين علي السعيدي
Abstract:
This thesis contains results of a extensive study for many important and fundamental properties of two organic dyes, these are Phenol Red and Light Green SF Yellowish. To obtain the dye doped polymer films used for our study, the Polymethylmethacrylate (PMMA) polymer was doped by each one of these dyes , at different concentrations : 0.01, 0.02, 0.03, 0.04, 0.05, 0.30, 0.40 mM . Effect of adding small amount of Iodine (I2) , as a dopant, to the constituents of the dye doped polymer films at concentration of 0.03 mM for each dye, on the optical and electrical properties of the polymer films, was also studied. Casting method was used for preparing the dye doped polymer films samples.The present work involves the study of the linear and the nonlinear optical properties, and the optical power limiting of the dye doped polymer films, as well as study of the electrical properties of these films.We have studied the optical properties of both the dye - doped polymer films and the dye - doped polymer films with Iodine (I2). The study includes the following parameters : absorbance (A), transmittance (T), reflectance (R),iiabsorption coefficient (α), extinction coefficient (k), refractive index (n), dielectric constant (ε) with its real (εr) and imaginary (εi) parts, optical conductivity (σopt.), electrical conductivity (σelec.), and optical energy band gap (Eg).The results of the optical properties show that the dye - doped polymer films having high transmittance (T) , low reflectance (R) , and low absorption coefficient (α ) , over the wavelengths of the visible spectrum, and these films have energy band gaps belong to the indirect transitions. While the dye - doped polymer films with added different doping ratio of Iodine (I2), have low transmittance (T) and an increase in the values of reflectance (R) and absorption coefficient (α ), particularly in the absorption regions over the wavelengths near the ultraviolet (UV) region of the the electromagnetic spectrum.To study the nonlinear optical properties of the dye - doped polymer films, the laser beam z - scan technique was used with solid state laser (SSL) operating at the continuous wave (CW) at 532 nm. The laser output can be varied within the range 0 - 100 mW. The obtained results showed that the samples of the dye - doped polymer films as well as the samples of the dye - doped polymer films with Iodine(I2) have a nonlinear refractive index with negative value (n2 < 0) (occurrence of the self - defocusing effect) and aiiinonlinear absorption coefficient with negative value also (β < 0) (occurrence of the saturable absorption).We have studied the optical power limiting for the prepared films samples , using the laser beam z - scan technique. We have obtained optical power limiting with good optical properties. The results revealed that the smallest value for optical power limiting threshold is 15 mW for the Phenol red dye doped polymer film sample at concentration of 0.03 mM with Iodine doping ratio 36.2 % of the dye weight.Also, The electrical properties of the prepared samples, the dye - doped polymer films and the dye - doped polymer films with Iodine (I2), have been studied using the current - voltage (I - V) characteristic for three temperature degree values , which are given to these samples, these are : 298 K, 308 K and 318 K. The values of the electrical conductivity (σ) and the electrical conductivity activation energy (Ea) of polymer film were calculated. The influence of changing the temperature on these parameters was studied.The results obtained from the present our study indicate that the two organic dyes, Phenol Red and Light Green SF Yellowish, are good candidates for optical applications and they could be used for the photonic devices, the photo - electronic devices , and also in the optical power limiting
