Effect of dopant concentration on the spectra characteristic in Zr4+ doped Yb:Nd:LiNbO3 crystals

(a) The OH− absorption peak for Zr-1 appears at 3482 cm−1, while the absorption peaks of Zr-2 and Zr-4 are shifted to 3489 and 3495 cm−1 differently. We can conclude that the ZrO2 doping threshold concentration is nearly 2.0 mol.%. (b) The fluorescence spectrum are characterized by two significant broad emission bands centered at 1019 and 1085 nm. The Zr4+ ion is beneficial to the increase fluorescence-emission intensity at 1019 and 1085 nm