Effect of hydroxyl groups on Er 3+-doped bismuth-borate glass and fiber

Abstract

A series of Er 3+-doped Bi 2O 3–B 2O 3–GeO 2–Na 2O glasses with different OH − group contents were prepared and the interactions between Er 3+ ions and OH − groups were investigated. The observed increase of the fluorescence intensity and decaying variation from an evident non-exponential to a nearly exponential behavior of the Er 3+: 4I 13/2 level with the oxygen gas bubbling time was related to the reduction of the OH − group contents evidenced by infrared (IR) absorption spectra, which demonstrated that the OH − groups were dominant quenching centers of the excited Er 3+. Meanwhile, by reducing the OH − group contents in the fiber cores with the same glass composition, the simulated gain characteristics improved dramatically and a 12.4 dB gain at 1560 nm was achieved in a 20 cm fiber with 150 mW pumping power at 980 nm.