Near-infrared emission of Bi-doped Bi-doped CdWO4 crystals grown by bridgman method

The CdWO4 crystals with good quality in the size of 25 mm × 100 mm, doped Bi2O3 in 0.5% molar fraction in the raw composition were grown by the bridgman method. The lower part of crystal which was grown at the initial stage appears yellow-green color, while the upper part of crystal blood-red color at final stage. The absorption spectra were recorded. The emission spectra of various parts of crystal were investigated when excited by 808 nm and 980 nm. The weak emission band at 1396-1550 nm (centered at 1504 nm) and strong band at 1037-1274 nm (centered at 1078 nm) were observed, and their lifetime were 238μs and 294μs, respectively. The emission intensity at 1504 nm increased as the growth direction, while the intensity at 1078 nm reduced as the growth direction. The mechanism for the band emission were discussed from the obtained spectra. The emission band at 1078 nm was probable related to Bi ion, while the weak band at 1504 nm was probable related to the defects of the crystal.