SITE-SELECTIVE UP-CONVERSION IN LINBO3ER3+

In this work, the infrared to visible up-conversion process in Er3+-do ped LiNbO3 crystals is presented. Green emission from the S-4(3/2) lev el was observed when the I-4(9/2) multiplet was excited (lambda almost -equal-to 800 nm). The wavelength dependence of both emission and exci tation spectra shows evidence of multi-site occupancy for the Er3+ ion s. Comparison of excitation spectra shows that the mechanism of the up -conversion process appears to be a combination of two different proce sses: excited state absorption and the APTE effect.