Absorption and photoluminescence of YAG:Er3+, YAG:Ce3+, and YAG:Er3++Ce3+ crystals

Enhanced NIR emission in Ce3+/Er3+-doped YAG induced by Bi3+ doping

“…In Ce 3+ /Er 3+ co-doped YAG, excitation of Er 3+ occurs mainly via energy transfer from the Ce 3+ −5d to the 4 F 7/2 state of Er 3+ when pumped under 469-nm laser. After excitation of the Ce 3+ − 5d state, the electrons either relax radiatively to the 4f ground state, thereby producing broad band luminescence in the visible range, or transfer to the 4 F 7/2 level of Er 3+ [2,6] . Electrons at 4 F 7/2 level of Er 3+ ions experience fast nonradiative decay to the 4 I 13/2 level and then decay to the ground state, thereby emitting at 1531 nm.…”

“…Thus, co-doping the matrix with corresponding sensitizers is necessary to enhance the absorption efficiency of Er 3+ ions. Good sensitizers for Er 3+ ions in different matrices include Cr 3+ , Yb 3+ , and Ce 3+ ions, which have broad and strong absorption bands in the visible and NIR spectral ranges as well as channels of efficient nonradiative transfer of the electron excitation energy to Er 3+ acceptor ions [6] . Ce 3+ ions are advantageous over the other donors because the dipole allows intra configuration of 4f →5d transitions of Ce 3+ , which are involved in the absorption and energy transfer processes, and the strengths of such transitions exceed those of parity forbidden intra configuration transitions by several orders of magnitude [7] .…”