The effect of BaF₂, MgF₂, and AlF₃ on the structural and luminescent properties of gallo-germanate glass (BGG) doped with erbium ions was investigated. A detailed analysis of infrared and Raman spectra shows that the local environment of erbium ions in the glass was influenced mainly by [GeO]₄ and [GeO]₆ units. Moreover, the highest number of non-bridging oxygens was found in the network of the BGG glass modified by MgF₂. The ²⁷Al MAS NMR spectrum of BGG glass with AlF₃ suggests the presence of aluminum in tetra-, penta-, and octahedral coordination geometry. Therefore, the probability of the ⁴I_13/2→⁴I_15/2 transition of Er³⁺ ions increases in the BGG + MgF₂ glass system. On the other hand, the luminescence spectra showed that the fluoride modifiers lead to an enhancement in the emission of each analyzed transition when different excitation sources are employed (808 nm and 980 nm). The analysis of energy transfer mechanisms shows that the fluoride compounds promote the emission intensity in different channels. These results represent a strong base for designing glasses with unique luminescent properties.

Nanophosphors are widely used, especially in biological applications in the first and second biological windows. Currently, nanophosphors doped with lanthanide ions (Ln³⁺) are attracting much attention. However, doping the matrix with lanthanide ions is associated with a narrow luminescence bandwidth. This paper describes the structural and luminescence properties of co-doped LaPO₄ nanophosphors, fabricated by the co-precipitation method. X-ray structural analysis, scanning electron microscope measurements with EDS analysis, and luminescence measurements (excitation 395 nm) of LaPO₄:Eu³⁺/Nd³⁺ and LaPO₄:Eu³⁺/Nd³⁺/Yb³⁺ nanophosphors were made and energy transfer between rare-earth ions was investigated. Tests performed confirmed the crystal structure of the produced phosphors and deposition of rare-earth ions in the structure of LaPO₄ nanocrystals. In the range of the first biological window (650–950 nm), strong luminescence bands at the wavelengths of 687 nm and 698 nm (⁵D₀ → ⁷F₄:Eu³⁺) and 867 nm, 873 nm, 889 nm, 896 nm, and 907 nm (⁴F_3/2 → ⁴I_9/2:Nd³⁺) were observed. At 980 nm, 991 nm, 1033 nm (²F_5/2 → ²F_7/2:Yb³⁺) and 1048 nm, 1060 nm, 1073 nm, and 1080 nm (⁴F_3/2 → ⁴I_9/2:Nd³⁺), strong bands of luminescence were visible in the 950 nm–1100 nm range, demonstrating that energy transfer took place.

LMA (Large Mode Area) optical fibers are presently under active investigation to explore their potential for generating laser action or broadband emission directly within the optical fiber structure. Additionally, a wide mode profile significantly reduces the power distribution density in the fiber cross-section, minimizing the power density, photodegradation, or thermal damage. Multi-stage deposition in the MCVD-CDT system was used to obtain the structural doping profile of the LMA fiber multi-ring core doped with Tm³⁺ and Tm³⁺/Ho³⁺ layer profiles. The low alumina content (Al₂O₃: 0.03wt%) results in low refractive index modification. The maximum concentrations of the lanthanide oxides were Tm₂O₃: 0.18wt % and Ho₂O₃: 0.15wt%. The double-clad construction of optical fiber with emission spectra in the eye-safe spectral range of (1.55–2.10 µm). The calculated LP₀₁ Mode Field Diameter (MFD) was 69.7 µm (@ 2000 nm, and 1/e of maximum intensity), which confirms LMA fundamental mode guiding conditions. The FWHM and λmax vs. fiber length are presented and analyzed as a luminescence profile modification. The proposed structured optical fiber with a ring core can be used in new broadband optical radiation source designs.

Glass-ceramic is semi-novel material with many applications, but it is still problematic in obtaining fibers. This paper aims to develop a new glass-ceramic material that is a compromise between crystallization, thermal stability, and optical properties required for optical fiber technology. This compromise is made possible by an alternative method with a controlled crystallization process and a suitable choice of the chemical composition of the core material. In this way, the annealing process is eliminated, and the core material adopts a glass-ceramic character with high transparency directly in the drawing process. In the experiment, low phonon antimony-germanate-silicate glass (SGS) doped with Eu³⁺ ions and different concentrations of P₂O₅ were fabricated. The glass material crystallized during the cooling process under conditions similar to the drawing processes’. Thermal stability (DSC), X-ray photo analysis (XRD), and spectroscopic were measured. Eu³⁺ ions were used as spectral probes to determine the effect of P₂O₅ on the asymmetry ratio for the selected transitions (⁵D₀ → ⁷F₁ and ⁵D₀ → ⁷F₂). From the measurements, it was observed that the material produced exhibited amorphous or glass-ceramic properties, strongly dependent on the nucleator concentration. In addition, the conducted study confirmed that europium ions co-form the EuPO₄ structure during the cooling process from 730 °C to room temperature. Moreover, the asymmetry ratio was changed from over 4 to under 1. The result obtained confirms that the developed material has properties typical of transparent glass-ceramic while maintaining high thermal stability, which will enable the fabrication of fibers with the glass-ceramic core.

This paper presents novel research on amorphous thin films doped with Er3+ ions deposited using the RF-sputtering method. The obtained layers' surface morphology, chemical composition, and optical properties were examined. Scanning electron microscopy analysis revealed a homogeneous layer structure with thicknesses ranging from 160185 nm. Energy-dispersive spectroscopy confirmed the presence of elements such as Ge, Ba, and Ga. Optical properties were measured using photoluminescence spectroscopy, showing emission in the range of 15201550 nm, indicating potential for the integrated optics emission sources. Full Text: PDF References J. Greene, "Review Article: Tracing the recorded history of thin-film sputter deposition: From the 1800s to 2017", J. Vac. Sci. Technol. A 35, 05C204 (2017). CrossRef S. Lee, J. Kim, S. Lee, H.-J. Cha, C.-S. Son, Y.-G. Son, D. Hwang, "Variations in the Physical Properties of RF-Sputtered CdS Thin Films Observed at Substrate Temperatures Ranging from 25 °C to 500 °C", Nanomaterials 12, 1618 (2022). CrossRef S. Asgary, E. Vaghri, M. Daemi, et al., "Magnetron sputtering technique for analyzing the influence of RF sputtering power on microstructural surface morphology of aluminum thin films deposited on SiO2/Si substrates", Appl. Phys. A 127, 752 (2021). CrossRef D.K. Maurya, A. Sardarinejad, K. Alameh, "Recent Developments in R.F. Magnetron Sputtered Thin Films for pH Sensing Applications—An Overview", Coatings 4, 756 (2014). CrossRef Y. Ju, L. Ai, X. Qi, J. Li, W. Song, "Review on Hydrophobic Thin Films Prepared Using Magnetron Sputtering Deposition", Materials 16, 3764 (2023). CrossRef J. Markiewicz, M. Kochanowicz, et al., "Broadband 1.5-2.1 µm emission in gallo-germanate dual-core optical fiber co-doped with Er3+ and Yb3+/Tm3+/Ho3+", Opt. Express 31, 28850 (2023). CrossRef M. Ismail, H. Farouk, M. Salem, A. Ashery, I. Battisha, "Optical properties of Er3+ doped phosphate glasses", J. Sci. Res. Sci. 36, 2019 (2020). CrossRef A. Răduță, A. Panaitescu, et al., "Effect of Deposition Working Power on Physical Properties of RF-Sputtered CdTe Thin Films for Photovoltaic Applications", Nanomaterials 14, 535 (2024). CrossRef K. Miura, Y. Arai, K. Kano, O. Hanaizumi, "Fabrication of Erbium and Ytterbium Co-Doped Tantalum-Oxide Thin Films Using Radio-Frequency Co-Sputtering", Mater. Sci. Appl. 6, 343 (2015). CrossRef E.A. Martín-Tovar, L.G. Daza, A.J.R. López-Arreguín, A.A. Iribarren Alfonso, R. Castro-Rodriguez, "Effect of substrate rotation speed on structure and properties of Al-doped ZnO thin films prepared by rf-sputtering", Trans. Nonferrous Met. Soc. China 27, 2055 (2017). CrossRef