The up-conversion processes in Ho3+ doped LiTaO3

The up-conversion processes in Ho3+ doped lithium tantalate were investigat ed under continuous wave excitation into the F-5(5), I-5(4) or I-5(5) multi plets and with the energy due to the I-5(6)--> S-5(2) transition, which is not resonant with the ground state absorption. The most intense green emiss ion originating from the S-5(2) multiplet is observed after excitation into the F-5(5) and I-5(4) multiplets. The excited state absorption spectrum, e mission spectra, dependencies of emission intensity on the excitation power as well as possible mechanisms of excitation are presented. (C) 2001 Elsev ier Science B.V. All rights reserved.