UP-CONVERSION OF MULTISITE ER IN LINBO3 SINGLE-CRYSTAL FIBERS

In this work, the near infrared to visible up-conversion process was s tudied in Er3+ doped LiNbO3 single-crystal fibers. The absorption spec tra of the I-4(9/2) multiplet and site-selective excitation of up-conv erted emission from the S-4(3/2) multiplet were measured at 10 K. Mult iple sites for Er3+ were found to exist in the fiber samples. They fal l into two groups which may be related to the substitution of Li and N b by Er. Near-infrared excitation spectra of the up-conversion and tra nsient dynamics have shown that either excited state absorption (ESA) or energy transfer up-conversion (ETU) processes play dominant roles a t certain pump wavelengths. In addition, laser-heating-induced up-conv ersion or photon avalanche up-conversion may also take place at some p ump wavelengths.