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As rare earth ion laser materials, any single kind type matrix can not satisfy the development requirements at the present stage, especially in the application of mid-infrared laser, which needs convenient operation, good physical and chemical properties and luminescent properties. In this study, nanocrystalline units are introduced into the glass structure to integrate their respective advantages and achieve the best balance, so as to obtain nanocrystalline-glass composites (NGC) with both crystal and amorphous properties. The results show that the emission intensity of the composited host is stronger than that of pure amorphous materials; particularly, the intensity of the 2.7 μm emission has been a significant improvement. Moreover, this method not only keeps the size of the nanocrystalline unit, but also affects the energy transfer making use of the nanostructure. Nano-glass ceramics thus might have a significant application potential; they might be used improve the performance of photonic devices and develop nano-integrated multifunctional materials.

As is well known, a way to obtain a high color resolution and saturation of a liquid crystal display and thereby obtain a higher visual accuracy and comfort in the coming 5G era remains an urgent challenge. In the present study, a new type of phosphor composite material doped with Ln3+ ions provides a promising alternative to the color filters used in White light-emitting diodes (WLEDs), achieving a better performance regarding the realization of a wider color gamut. The advantages of this composite material are illustrated through an abundant phase and morphology analysis along with a discussion regarding the X-ray photoelectron spectroscopy of the valence bond of Ce ions, which maintain the luminescence properties of the phosphor while providing a stable and solid amorphous environment. An improved spectral performance was obtained through color filtering at 580 nm along with the regulating effects of red, green, and blue emissions according to the doped Ln3+ ions. Notably, we fabricated a high-performance WLED based on a Ln3+-doped PiG with a correlated color temperature of 5037 K, color rendering index of 72.8, and high color gamut of 91.97%, providing a new choice for the development of luminescence materials with a high color resolution and saturation.

A system of zinc fluoride glasses were synthesized to analyse the sensitization mechanism between doped Ln3+ ions under 808 or 980 nm excitation. Differential scanning calorimetry (DSC) curve and Raman spectra indicate the favourable thermal stability and a low maximum phonon energy of the host. Judd-Ofelt (J-O) theory together with the absorption spectra were utilized to compute the Ωt for predicting radiative features of each sample which coincide with the later measured emission spectra. Broadband emission ranging from 2400 to 3300 nm with a half-width of 361 nm in Er3+/Dy3+ codoped zinc fluoride glasses under 980 nm pumping has been investigated, which may be applicated in mid-infrared fiber amplifier and broadband tunable lasers field. On the other hand, the efficient sensitization effect mechanism between Er3+ and Dy3+ around 3 μm band with an extremely high energy transfer efficiency Ƞ (96.1%) of Er3+:4I13/2→Dy:6H11/2 has been researched under 808 nm excitation. Hence, Er3+ and Dy3+ doped zinc fluoride glasses may be potential optical candidates of great development foreground in the fields of mid-infrared applications.

Increasing the number of luminescence emitters without concentration quenching is essential to realize the high doping in silicate glass system, which is favorable for the output of single-frequency fiber lasers. In this work, the concentration quenching threshold of mid-infrared luminescence is enhanced by 60% after macro-scale manipulation of glassy structure. The reason can be attributed to the reduced maximum phonon energy after the increasing of Pb content and the increasing number of emitters due to the looser glassy network. The absorption and emission cross sections after structural engineering can reach to 0.75 × 10–20 cm2 and 1.53 × 10–20 cm2, respectively. These results reveal that the concentration quenching threshold can be effectively enhanced through the structural manipulation in a wide range, and the prepared lead silicate glass after structural engineering can be the ideal candidate for drawing optical fiber and are potential in future optical applications.

Highly rare earth（RE）ions doped glass laser materials can produce efficient single frequency mid-infrared laser. In this work, a series germanosilicate glasses with various high erbium-doping concentration (up to 4 mol%) and without concentration quenching are fabricated. Spectroscopic properties and energy transfer (ET) mechanism of efficient Er3+:4I11/2 →4I13/2 transition have been investigated in detail upon a conventional 980 nm Laser Diode. The dense structure of silicate glass can be dissolved effectively by the introduction of GeO2, which was analyzed by Raman spectra, so that the compatibility and luminous intensity of RE ions were improved. The high predicted spontaneous transition probability (Arad = 37.65 s−1) based on the Judd-Ofelt theory and large calculated emission cross section (8.8 × 10−21 cm2) are obtained. The above results indicate that these glasses are promising to be the single frequency mid-infrared laser material.

This paper investigates 2.9 μm emission properties and energy transfer processes in the Dy3+/Tm3+ codoped fluorotellurite glass. The measured absorption spectra demonstrate that the codoped sample can be efficiently pumped by an 800 nm excitation. Judd–Ofelt and radiative parameters are calculated and discussed. Higher spontaneous emission probability (39.6 S−1) provides a better probability to obtain laser action. Obvious 2.9 μm emission of Dy3+: 6H13/2→6H15/2 transition is observed after codoping with Tm3+ and the optimum ratio in this system is 1:1. Energy transfer processes between the two ions are discussed and the related microscopic interaction parameters are calculated. Hence, these results indicate that the Dy3+/Tm3+ codoped fluorotellurite glass is a suitable material for developing solid state laser at approximately 3.0 μm.

The upconversion luminescence of Er3+-doped fluoride glass under 1550 and 980 nm pumpings is investigated. The emissions pumped by 488 nm excitation is also obtained and used as a comparison. Absorption and emission spectra are tested and visible to infrared emissions (520, 550, 667, 800, 850, 980, 1535, and 2708 nm) are clearly observed. Upconversion luminescence from 980 or 1550 nm to green or red visible luminescence is a two or three-photon process, respectively. The red to green emission intensity ratios are 0.06 and 0.11 when the sample is excited under 488 and 980 nm pumpings, respectively. However, significantly brighter red emission is observed under 1550 nm pumping and the ratio is as high as 12.5, which is most decided by non-radiative decay processes between 4I9/2 and 4I11/2 levels. In addition, mechanisms of the upconversion by multiphoton absorption and energy transfer processes are discussed based on the energy-level diagram of Er3+ and upconversion luminescence spectra. These results benefit investigations on upconversion luminescence materials, particularly Er3+-doped glasses.