Study On The Growth And Spectra Characteristics Of Doped BaWO₄ Crystal

The BaWO4 crystal is a novel Raman crystal. In this paper its growth technology was deeply studied and it was also studied as laser crystal host.The device, process and influence factors of crystal growth were analyzed in detail. Optimum technical parameters were obtained through the integration of theory with practice. High quality BaWO4,Yb3+:BaWO4 and Yb3+, Er3+:BaWO4 crystals were grown with Czochralski method.Cell parameters of the crystals were determined by XRD. The results show that crystal structure was not affected largely after rare earth ions were doped. Raman spectra were tested with x ( zz )x , z ( xy )z , x ( yy )x , x ( yz )x four configurations at room temperature. Vibration modes were assigned by comparing and analyzing the different Raman spectra. The crystal structure was analyzed as well.Polarized absorption spectra of Yb3+:BaWO4 were observed. Fluorescence spectrum excited with the 930 nm was tested. Energy levels of Yb3+ were assigned through analyzing the absorption and fluorescence spectra. The oscillator strength, transition probability and radiacive lifetime were calculated by Judd-Ofelt theory. Absorption spectra of Er3+, Yb3+:BaWO4 were tested and energy levels of Er3+ were assigned. Moreover the absorption coefficient and absorption cross section of corresponding energy level were calculated. Fluorescence spectra excited with the 334 and 976nm were measured and energy level transitions were discussed. According to Judd-Ofelt theory, the spectral strength parameters of Er3+ ion were fitted to be: 2=0.3926×10-20cm2 , 4=0.0721×10-20cm2 , 6=0.0028×10-20cm2. Furthermore spontaneous emission probability, radiative lifetime, fluorescence branching ratio and integrated emission cross-section for radiative transitions were also calculated.Up-conversion luminescent of Er3+, Yb3+:BaWO4 was discussed. Fluorescence spectra excited with the 808 and 976nm were measured. The channels of frequency up-conversion were indicated according to the up-conversion spectra. Different mechanisms of up-conversion sensitization were analyzed.