2 μm emission properties and nonresonant energy transfer of Er3+ and Ho 3+ codoped silicate glasses

Abstract

2.0 μm emission properties of Er 3+/Ho 3+ codoped silicate glasses were investigated pumped by 980 nm LD. Absorption spectra were determined. Intense mid-infrared emissions near 2 μm are observed. The spectral components of the 2 μm fluorescence band were analyzed and an equivalent model of four-level system was proposed to describe broadband 2 μm emission. Low OH - absorption coefficient (0.23 cm -1), high fluorescence lifetime (2.95 ms) and large emission cross section (5.61 × 10 -21 cm 2) corresponding to Ho 3+: 5 I 7→5 I 8 transition were obtained from the prepared glass. Additionally, energy transfer efficiency from the Er 3+: 4 I 13/2 to the Ho 3+: 5 I 7 level can reach as high as 85.9% at 0.75 mol% Ho 2 O 3 doping concentration. Energy transfer microscopic parameters (C DA) via the host-assisted spectral overlap function were also calculated to elucidate the observed 2 μm emissions in detail. Moreover, the rate equation model between Er 3+ and Ho 3+ ions was developed to elucidate 2 μm fluorescence behaviors with the change of Ho 3+ concentration. All results reveal that Er 3+/Ho 3+ codoped silicate glass is a promising material for improving the Ho 3+ 2.0 μm fiber laser performance.