Optical Properties Of Rare Earth Doped PLZT And Its Electro-optical Application

The works in this thesis are on the basis of the projects ,which origin from our cooperative item with BATI( Boston Applied Technologies, Incorporated). The content of projects include that study on optical characteristics, radiative properties of rare earth doped PLZT and provide a physical supply for devolopment of new optical devices. For these goals, the optical properties, radiative properties of rare earth doped PLZT and PLZT's application on Q-switch will be studied in this thesis.1. Based on Judd-Ofelt(J-O)theory, the J-O intensity parameters were calculated using the emission spectrum of Nd doped PLZT. The J-O intensity parameters have been used to calculate the radiative transition probabilities of the ⁴F_3/2→⁴I_J, transition, the radiative lifetime of ⁴F_3/2 level and the stimulated emission cross-section of the ⁴F_3/2→⁴I_J, transition.The fluorescence lifetime of the ⁴F_3/2 was measured.2. Optical properties of defferent Tm3+ concentration doped PLZT have been discussed in detail. Three sets of Judd-Ofelt parameters show that the ion concentration of 7% does not infect host environment . From the results of experiments and theory analysis, We can conclude that 7% doped concentration is sutible for development of active photonic devices at the waveband of 1.8μm.3. We fist report that unde 980nm laser excitation, visible up-converted luminescence spectra of Er and Er/Yb in PLZT have been observed . Lasers power dependence on upconverted emissions revealed that two-photon process lead to green or red emissions. Green light from upconversion of Nd in PLZT is also observed. Its two upconversion mechanisms: exiced state absorption and energy transfer is discussed specificly.4. We apply Variable Optical Attenuater(VOA) as Q-switch of Er doped fiber laser.1560nm Q- pulse laser is obtained under no bias voltage ,but working voltage is only 255 V, which is much smaller than that of LiNbO3 or KDP.The innovation points and high lights of this thesis include:1 .Based on Judd-Ofelt(J-O)theory, the J-O intensity parameters are calculated using the emission spectrum of Nd³⁺ doped PLZT. The intensity parameters have been used to evaluate the various radiative parameters, such as induced-emission cross section , lifetime of metastable state and quantum efficiency, for the Nd3+ ions doped PLZT.2. Through the research on optical characteristics of different Tm³⁺ concentration doped PLZT, three sets of J-0 intensity parameters show that enven if doping content of 7% Tm³⁺ , PLZT'lattice is not yet distorted. In the waveband of 1.8μm , fluorescence intensity of 7% doping content is much stronger than that of 3% and 1%. Though the radiative lifetime of 7% is a little shorter than that of 3% and 1%, it is comparable to those of commercial Tm³⁺ doped laser glasses. Combining the theoretical analysis and experimental results ,we hold that Tm doped PLZT with 7% doping concentration is more suitable for development of optical devices at the waveband of 1.8μm.3. We have acquired some rules about upconversion luminescence of Er, Er/Yb, Nd doped PLZT. We find that Er/Yb doped PLZT is a very efficient material for upconversion. It may be acted as a probable material for upconversion laser at the same time it has a high e-o coefficient. In three ions doped conditions, the relationship between luminescence power and pump power all verify that the visible upconversion process is two-photon emission mechanism. We also successfully observed upconversion luminescence of Nd doped PLZT at the pump of 807nm.4. First we research some characteristics of VOA based on PLZT. Then we use it as an E-0 Q-switch of Er doped fiber laser. Under the condition of work voltage at 255V, We successfully get a steady-going Q-swith pulse.