Judd–Ofelt analysis and energy transfer processes of Er3+ and Nd3+ doped fluoroaluminate glasses with low phosphate content.

Spectroscopic property and energy transfer processes of singly doped and codoped Er 3+ and Nd 3+ fluoroaluminate glasses with low phosphate content are systematically analyzed. The absorption spectra of these glasses are tested, and the Judd–Ofelt (J–O) and radiative parameters are discussed based on J–O theory and the parameters changes substantially because of the other codoping ions. As for Nd 3+ : the main emission bands at 0.9 and 1.05 μm decrease in the codoped sample under the excitation of an 800 nm laser diode from the emission spectra because the Er 3+ : 4 I 11/2 level reduces the Nd 3+ : 4 F 3/2 level effectively through the energy transfer process Nd 3+ : 4 F 3/2 → Er 3+ : 4 I 11/2 . For Er 3+ , the emission at 1.5 μm is restrained by codoping with Nd 3+ ions from the energy transfer process Er 3+ : 4 I 13/2 → Nd 3+ : 4 I 15/2 . The emission at 2.7 μm is enhanced because the Nd 3+ ions deplete the lower level and exert a positive effect on the upper laser level. The microparameters of the energy transfer between the Er 3+ and Nd 3+ ions are calculated and discussed using Forster–Dexter theory. The energy transfer efficiencies of the Nd 3+ : 4 F 3/2 to the Er 3+ : 4 I 11/2 and the Er 3+ : 4 I 13/2 to the Nd 3+ : 4 I 15/2 are 28.8% and 74.5%, respectively. These results indicate that Nd 3+ can be an efficient sensitizer for Er 3+ to obtain Mid-infrared (Mid-IR) emission and the codoped Er 3+ /Nd 3+ fluoroaluminate glass with low phosphate content is suitable to be used as the fiber optical gain media for 2.7 μm laser generation. [ABSTRACT FROM AUTHOR]