Study On Growth And Properties Of Er³⁺/Yb³⁺ Codoped KGd(WO₄)₂ Laser Crystal

The Er³⁺/Yb³⁺-codoped KGd(WO₄)₂ crystal is a new type of laser materials, which has been used widely for laser medical treatment, laser ranging and laser communication.Through using K2W2O7 as flux and designing rational process parameters, the Er:KGW and Er:Yb:KGW crystals of high optical quality were grown by Top Seeded Solution Growth(TSSG). The optimal doping concentrations of two crystals were selected. The doping concentration of Er³⁺ ions was 5at.% in Er:KGW crystal while Er³⁺ and Yb³⁺ ions were 1at.% and 10 at.% respectively in Er:Yb:KGW crystal. Then the structure and performance of two crystals were compared.1. The main defects containing cracking and wappage of crystal were analyzed, and the measurement of decreasing and eliminating defects were put forwarded.2. The structure of crystal was verified and the cell parameters of them were calculated by XRD analysis.3. Through TG-DTA analysis, the melting point and phase transition temperature of crystals were determined.4. The infrared spectra and Raman spectra of crystal were measured, and the vibration frequencies of infrared and Raman active modes for crystal were assigned.5. The absorption and emission spectra were measured. According to J-O theory, the spectral parameters were calculated, such as absorption and emission cross section, intensity parameters, radiative transition probability, fluorescence branch ratio, fluorescence lifetime and so on.6. The mechanism that Yb³⁺ ions sensitize Er³⁺ ions in Er:Yb:KGW crystal was discussed, and the up-conversion luminescence process of active ions was analyzed.