Surface plasmon resonance-enhanced 2 μm emission of bismuth germanate glasses doped with Ho3+/Tm3+ ions

• Ag nanoparticles with 5–10 nm were dispersed into the bismuth-germanate glasses.
• 2 μm emission of Ho3+/Tm3+ ions was enhanced by SPR of Ag nanoparticles.
• Comparative performances show potential applications for the laser media.

In this paper, we report 2 μm emission in bismuth germanate glasses doped with Ho3+/Tm3+ ions enhanced by surface plasmon resonance of Ag nanoparticles (NPs) under 800 nm laser excitation. We perform broadband mid-infrared emissions from 1700 nm to 2200 nm corresponding to Tm3+: 3F4 → 3H6 and Ho3+: 5I7 → 5I8 transitions. The energy transfer from Tm3+ to Ho3+ ions results in a strong 2030 nm emission. Results demonstrate that the emission intensity of the sample containing Ag NPs is much higher than that of the sample without Ag addition. For the best AgTH6 sample, the absorption and emission cross sections of Ho3+ transition (5I8 → 5I7) reach 0.5 × 10−20 cm2 at 1945 nm and 0.78 × 10−20 cm2 at 2030 nm, respectively. The comparative performances, i.e., σe × full width at half maximum and σe × τ, are approximately 129 × 10−20 cm2 nm and 24.8 × 10−24 cm2 s, respectively. Therefore, the glass has a potential application as 2.0 μm laser active media.