•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.

•Ag nanoparticles composited glasses were facilely synthesized.•SPR absorption band of Ag nanoparticles is located from 500 to 1500 nm.•7.2-Folds enhancement of the intensity of 1.54 μm emission of Er3+ ions by SPR.Vitreous materials containing rare-earth (RE) ions and metallic nanoparticles (NPs) attract considerable interest because the presence of the NPs may lead to an intensification of luminescence. In this work, the characteristics of 1.54 μm luminescence for the Er3+ ions doped bismuthate glasses containing Ag NPs were studied under 980 nm excitation. The surface plasmon resonance (SPR) band of Ag NPs appears from 500 to 1500 nm. Transmission electron microscopic (TEM) image reveals that the Ag NPs are dispersed homogeneously with the size from 2 to 7 nm. The strength parameters Ωt(t = 2, 4, 6), spontaneous emission probability (A), radiative lifetime (τ) and stimulated emission section (σem) of Er3+ ions were calculated by the Judd–Ofelt theory. When the glass contains 0.2 wt% AgCl, the 1.54 μm fluorescence intensity of Er3+ reaches a maximum value, which is 7.2 times higher than that of glass without Ag NPs. The Ag NPs embedded glasses show significantly fluorescence enhancement of Er3+ ions by local field enhancement from SPR.

•Visible to 1020 nm near-infrared downconversion emission occurred.•The highest quantum efficiency is 114 %.•Lifetimes decline from 92 to 79 μs with increasing Yb3+ concentration.Near-infrared downconversion which can be used to improve the utilization of solar spectral has drawn much attention. In this work, chalcohalide glasses with compositions of 50GeS2–25Ga2S3–25CsCl (in mol.%): 0.1 wt.% Tm2 S3 - x wt.% Yb2S3 (x = 0, 0.1, 0.2, 0.3) were synthesized by vacuumed melt-quenching method. Absorption spectra, emission spectra, excitation spectra, and decay measurements were performed to prove the occurrence of cooperative energy transfer from the 1G4 level of Tm3+ ions to two Yb3+ ions. Quantum efficiency depends on Yb3+ concentration is calculated, and the highest is 114.1%. The photon energy of Yb3+ emission around 1 µm well matched with the operation band gap of the crystalline Si, so the glasses could potentially be applied in Si-based solar cell.

The present GeTe4-AsTe3-AgI glasses extend the optical window to up to 25 μm and its glass-forming region has been explored for practical applications. Their structure, glass-forming ability, thermal stability, infrared transmitting properties were investigated. The results reveal that the GeTe4-AsTe3-AgI glasses exhibit a large glass-forming region situated around the GeTe4-rich domain. Raman analysis confirms the formed [GeTe3I] and [AsTe2I] units are mainly responsible for the improvement in glass-forming ability. The optimum 40GeTe4-30AsTe3-30AgI glasses exhibit a large optical window extending from 2 to 25 μm while being stable enough toward crystallization to permit the preparation of fibers and molded lenses. Under proper annealing at 150 °C, 40GeTe4-30AsTe3-30AgI glass-ceramics, with high mechanical and thermal properties while still keeping the IR transmittance unchanged, were obtained for the first time.