Preparation Of Rare Earth Doped Glass Ceramics And Study On Microcrystalline Fiber

Nowadays,laser technology has widely applied in all walks of life especially³?m wave range,whose applications are broad and meaningful including many important areas covering communications,medical treatment,military,environmental monitoring and bioengineering.The gain medium of³?m laser is generally Er³⁺ions as activating ions,and the matrix possesses lower phonon energy as host material.At present,there are lots of rare earth doped laser materials studied widely,including glass,crystal,ceramics,glass ceramics and fiber.Factors affecting mid-infrared emission are multi-phonon relaxation,OH^-concentration and concentration quenching.In order to obtain efficient mid-infrared emission,matrices are usually used lower maximum phonon energy materials and rare earth doping concentration is chosed the appropriate proportion.In this work,we proposed to enhance 2.7?m and 3.5?m fluorescence by changing matrix phonon energy or dopant concentration.1.Er³⁺-doped oxyfluoride germanate glass containing LaF₃ nanocrystals have been prepared via heat treatment from the precursor glass.When heat treat temperature increased from 540?to600?,NIR and MIR fluorescence intensity increase about 3 times,and companied with 2060 times550nm and 350 times 660nm fluorescence enhancement.Increasing the heat treat time at 560?from 2 to 12 hours,the NIR and MIR fluorescence intensity increased about 2.5 and 1.8 times.It was due to the part of Er³⁺ions were incorporated into LaF₃ nanocrystals,resulting in the decrease of the mutli-phonon relaxation of Er³⁺.According to the ratio between MIR fluorescence intensity of the heat treated glass sample to that of the untreated glass sample,the number of the Er³⁺which was incorporated into the LaF₃ nanocrystals can be quantificationally estimated.It was estimated to be 0.98%to 5.8%when the heat treat temperature increased from 540?to 600?,and 1.21%to1.63%with increasing heat treat time from 2 to 12 hours.2.As to the effect of rare earth ions fluorescence in Te-based glass and rare earth concentration,we prepared Te-Er binary oxide glass.With the increasement of introduced Er₂O₃ concentration,the NIR 1.5?m fluorescence intensity and lifetime decreased gradually,MIR 2.7?m intensity strengthened and then weakened,MIR 3.5?m intensity increased step by step,and upconversion550nm and 670nm fluorescence intensity and lifetime was downtrend.These were due to the energy resonance and cross-relaxation process between the rare earth ions leading to the change in the number of particles on each luminescence level.3.Er₂Te₅O₁₃ crystal has been prepared successfully via heat treatment from 94TeO₂-6Er₂O₃glass.XRD patterns showed that heat treatment under 460?and 440?was a complete crystallization process,in which the fluorescence intensity and lifetime didn't enhance obviously on account of the little difference of phonon energy between crystals and matrix glass.4.Tellurium germinate precursor glass fiber was drawn by the tube rod method combined with the core melting method,and the glass-ceramic fiber was successfully prepared by subsequent heat treatment in 350?,370?,390?,410?and 430?.Due to partial Er³⁺ions incorporated into nanocrystals precipitated from the matrix,measurement results showed that 1.5?m intensity increased 2.13 times and the lifetime added from 5.16ms to 6.11ms;2.7?m intensity increased 2.02times but 3.5?m intensity had no significant enhancement;545nm and 655nm upconversion intensity increased 2.54 times while the two bands lifetime had no evident changes.Experiments show that the rare earth luminescence intensity and lifetime can be enhanced by the precipitation of micro-nanocrystals and the increase of rare earth concentration.