Discrepancies between Pr3+ and Ho3+ de-sensitized Er3+:2.7 μm emission

This paper studied the de-sensitization effect of Pr3+ and Ho3+ to Er3+:2.7 μm emission. Results show that both Pr3+ and Ho3+ are effective de-sensitizers, while great differences exist between them because of their non-phonon and phonon assisted energy transfer (ET) mechanisms. Ho3+ depresses the 2.65 μm emission while Pr3+ strengthens it greatly. ET coefficient indicates that Pr3+ performs ten times higher 4I13/2 depletion ability than Ho3+. In Er/Ho glasses, about 1/10 energy back transfers to 4I13/2 level, which partially counterweights the depopulation of 4I13/2 level. The high absorption cross section of Ho3+ is the reason for the larger 4I11/2→5I6 ET coefficient. Line strength and spontaneous radiation probability of 4I11/2→4I13/2 transition enhance moderately in E, E/H and E/P order, proving that the de-sensitizers promote the 2.7 μm transition positively. Long lifetime of Ho3+:5I6/5I7 brings many problems, such as energy back transfer and strengthened upconversion, which also implies that the interactions of the particles obstruct the effective 4I11/2→4I13/2 transition correspondingly.