الخواص البصرية اللاخطية ومحدد القدرة البصري للصبغات العضوية في المحاليل والاغشية البوليمرية باستخدام تقنية مسح حزمة الليزر على المحور z == Nonlinear Optical Properties and Optical Power Limiting of Organic Dyes in Solutions and Polymer Films Using The Laser Beam Z - Scan Technique
Author name:
سيف الدين عبد الكريم قاسم
Supervisor name:
عماد الدين حسين علي السعيدي
General topic:
Physics
Specific topic:
Physics
Degree:
Master
University:
University Of Basrah - College Of Education For Pure Sciences
Language:
Arabic
University location:
Basrah
First pages:
26T1677 - p.pdf
Abstract:
The research in this thesis is concerned with our extensive study of the spectral properties, the nonlinear optical properties, and the optical power limiting effect, for three organic dyes : Leishman, Giemsa, and Brilliant Cresyl Blue. Three different solvents were used to dissolve each dye : Chloroform, Ethanol, and Dimethyl(formamide) (DMF).We prepared dye solutions at four different concentrations : 0.03 mM, 0.05 mM, 0.07 mM, and 0.09 mM. Dye doped polymer films at concentration 0.09 mM were also prepared by mixing the dye with the polymer poly(methylmethacrylate) (PMMA) which already dissolved in the chloroform and using the casting method to obtain the desired polymer films.The linear absorption spectra of the dye solutions and the dye doped polymer films for different concentrations were analyzed by using the double - beam spectrophotometer in order to find the spectral range for each dye .2Our study was focused mainly on the nonlinear optical properties of the dye solutions and the dye doped polymer films. We employed in this study the laser beam z - scan technique and the solid - state laser (SSL) operating with the continuous wave (CW) at wavelength 532 nm and with variable output power over the range 0 - 100 mW .We have also studied the effect of the laser beam intensity on the nonlinear optical parameters of the dye solutions prepared by dissolving each dye in the Dimethyl(formamide) (DMF) solvent. Two values for the laser beam intensity were used for irradiating the samples (The dye solutions), these are : 1.11 kW / cm2 and 2.22 kW / cm2.Our obtained results from the present study reveal that all solutions of the three dyes and the dye - doped polymer films have a negative value for the nonlinear refractive index (n2 < 0) (occurrence of the self - defocusing effect) and also a negative value for the nonlinear absorption coefficient (β < 0) (saturable absorption).The values of the nonlinear optical parameters for each dye were calculated, these parameters are : The nonlinear refractive index (n2), the nonlinear absorption coefficient (β), and the absolute value of the nonlinear optical susceptibility (|χ(3)|). The solvents effect on the values of these optical3parameters was studied, and we find that the solvent plays an important role on the variation of these values.We also studied the optical power limiting for the dye solutions and the polymer films by using the laser beam z - scan technique. Good optical power limiting properties were obtained. The values of the optical power limiting threshold for the dye solutions at different concentrations and also for the dye doped polymer films were determind. We note that the value of the optical power limiting threshold depends on the kind of the used solvent for dissolving the dye. The smallest value for the optical power limiting threshold is 6.7 mW for the Brilliant Cresyl Blue dye doped polymer in chloroform at concentration 0.09 mM, while the smallest value for the power limiting threshold for the Brilliant Cresyl Blue solution in the same solvent at concentration 0.09 mM is 7.8 mW. The value of the power limiting threshold depends the kind of the used dye or the kind of the used solvent in preparing the sample and also on the concentration of the dye.The results that we have obtained from our present study show that the three dyes, Leishman, Giemsa, and Brilliant Cresyl Blue exhibit large nonlinear optical effects, suggesting that they are good promising materials for applications in the nonlinear photonic devices, the optical power limiting, and other optical devices.
