[Study on the growth and spectral characteristics of LiNbO3:Cr:ZnO crystal]

The LiNbO3:Cr:ZnO crystals with the size up to phi20 mm x 50 mm were grown by the Czochralski technique. The absorption spectrum shows that there are two strong absorption wideband peaks and one weak absorption peak of to Cr3+ ion in the crystal. The peak values of the two strong absorption wideband peaks are 480 and 660 nm, which correspond to 4A2-->4 T1 and 4A2-->4 T2 transitions, respectively. The weak absorption peak at 727 nm corresponds to 4A2-->2 E(R line) transition; The fluorescence spectrum shows that one emission wideband peak ranging from 802 to 988 nm coexists with one weak emission peak at 754 nm corresponding to 4T2-->2 E transition. The peak value of emission wideband is at 871 nm, which corresponds to 4T2-->4A2 transition. The crystal field and Racah parameters were calculated, and Dq/B = 2.72 indicates that it has an stronger crystal field. The result shows that the wideband tunable laser can be obtained from this crystal because it not only has the necessary spectral characteristics required for tunable laser crystal but also has good physical chemical properties. Furthermore, the UV laser at about 420 nm can also be obtained from the crystal by its self-frequency doubling because it has a higher frequency-doubling coefficient.