Enhanced effect of Er3+ ions on 2.0 and 2.85 μm emission of Ho3+/Yb3+ doped germanate-tellurite glass

• The enhanced Ho3+ 2.0 and 2.85 μm emission was reported in the Yb3+/Ho3+ co-doped germanate-tellurite glass.
• The glass possesses considerably low OH− absorption coefficient (0.118 cm−1).
• The energy transfer coefficient (CDA) between Yb3+, Er3+ and Ho3+ were analyzed.

We report what we believe is the first demonstration of the enhanced Ho3+ 2.0 μm (2.1 times) and 2.85 μm (2.6 times) emission by addition of Er3+ in the Ho3+/Yb3+ co-doped germanate-tellurite (GT) glass with optimized extra-low hydroxyl content ∂OH−∂OH− (0.118 cm−1). Meanwhile, enhanced 2.0 and 2.85 μm emission cross-sections (5.78 × 10−21 and 17.9 × 10−21 cm2) can be approximately increased 1.5 times higher, respectively. The enhanced 2.0 and 2.85 μm emission upon excitation of a conventional 980 nm laser diode are investigated by the analysis of energy transfer. In addition, the energy transfer mechanism and coefficient (CDA) from Yb3+ to Ho3+ and Er3+ to Ho3+ have been investigated in detail. Our results indicate that Ho3+/Er3+/Yb3+ triply-doped GT glass is a promising material for 2.0 μm and 3 μm fiber laser.