Luminescence Characteristics Of Rare Earth Doped PLZT Ceramics And Their Relationship With The Trap Distribution

With the development of scientific research,visionary people are growing attention gradually towards the important value of rare earth(RE)doped lead lanthanum zirconate titanate(PLZT)ceramic materials for their great potential in practical applications.Benefiting from the rich energy level structures of RE ions,PLZT shows many new performances,the controllability and tunability of fluorescence make it widely seen as multifunctional laser materials,optical devices,etc.The advancement of thin-film technology also makes it possible in miniaturization and integration of the devices.Recently,weak localization of photons,along with random lasing action were observed in RE-doped PLZT gain media when illuminated with strong laser light owing to its rich traps,which offer opportunity in developing new generation of photonic devices.In this thesis,we investigated photoluminescence in RE doped PLZT ceramics by attempting to understand the roles played by the type and concentrations of RE ions and the pump sources,to analyze the intrinsic link between the distribution of internal charge carrier traps in PLZT and fluorescence lifetime,and to lay a foundation for designing and building new optical devices for the applications with RE doped PLZT,such as optical amplifiers,optical modulators.The photoluminescence spectra obtained in different RE doped PLZT ceramic films show that the luminescence intensity and the branching ratio between different peaks are closely related to the type and concentration of RE ions,body temperature,pumping power and so on.The fluorescence spectra of Ho、Tm:PLZT show that under high pump power,the slopes of double logarithmic curve of emission power versus pumping power at all emission peaks are smaller than the required number of photons for typical upconversion process,which is consistent with our theoretical consideration of energy transferring processes between multi-levels.By introducing the charge carrier trap picture in PLZT ceramics,we established a modified model regarding PLZT host materials and RE ions.The experimental results of luorescence lifetime in Ho、Tm:PLZT prove that it can be used as a storage medium for “secondary excitation”,and also indicate that stimulated amplification can be realized in RE doped PLZT ceramic materials,which paves the way for extended further application of RE doped PLZT ceramics.