Effect of Zn2+ Ions on Upconversion Emission of Er3+ in Zn/Er:LiNbO3 Crystal

The effect of Zn2+ ions codoped on the upconversion emission of Er3+ ions in Er:LiNbO3 crystal under different excitation wavelength was reported. The upconversion emission spectra of Zn/Er:LiNbO3 following 800 nm excitation reveal an enhanced green emission and a suppressed red emission simultaneously. The cross relaxation processes(H-2(11/2)+I-4(13/2)-> I-4(11/2)+F-4(9/2) and F-4(7/2)+I-4(11/2)-> F-4(9/2)+F-4(9/2)) are responsible for populating the red F-4(9/2) emitting state. The dissociation effect of Zn2+ ions on the Er3+ cluster sites makes these cross relaxation processes inefficient. Under 980 nm excitation, the Zn2+ codoped leads to the decreased intensities of green and red upconversion emissions. These reductions are attributed to the inefficient cross relaxation F-4(7/2)+I-4(11/2)-> F-4(9/2)+F-4(9/2)) caused by the same dissociation effect of Zn2+ ions.