Broadband ~1.8 µm emission characteristics of Tm3+-doped bismuth germanate glass based on Ga2O3 modification

• Published in: Journal of non-crystalline solids 2021-04, Vol.557, p.120575, Article 120575
• Main Authors: Song, Xiangyang, Han, Kexuan, Zhou, Dechun, Xu, Pengfei, Zhang, Peng
• Format: Article
• Language: English
• Subjects: 1.8 µm emission; Bi2O3-GeO2-Ga2O3 glass; Energy transfer; Thulium
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2020.120575

•Tm3+-doped Bi2O3-GeO2-Ga2O3Na2O glass was prepared by melt-quenching method.•Effects of Ga2O3 on thermal stability and emission properties were studied.•The prepared glass has relatively low maximum phonon energy (745 cm−1).•Large σemi×τm and σemi × ∆λeff indicate good gain properties of prepared glass.•Energy transfer coefficient of cross relaxation process is calculated. In this paper, Tm3+-doped Bi2O3-GeO2-Ga2O3Na2O glass was synthesized using melt-quenching method. Spectroscopic and thermal properties of the presented glass was characterized. The effects of Ga2O3 oxide on the glass structure and ~1.8 µm emission properties were investigated. The thermal stability and Raman spectroscopic analysis showed that partial substitution of GeO2 by Ga2O3 resulted in decreasing of glass transition temperature and maximum phonon energy (745 cm−1). It is known that relatively low maximum phonon energy is good for ~1.8 µm emission. Based on the measured absorption spectra, Judd-Ofelt intensity parameters and other spectroscopic parameters were calculated to elucidate the radiative properties of the presented Tm3+-doped glass. Moreover, under the excitation of 808 nm laser diode, broadband ~1.8 µm fluorescence was observed. For Bi2O3-GeO2-Ga2O3Na2O glass doped with 1.0 mol% Tm2O3, the large values of σemi × τmea product (8.30 × 10−21 cm2ms) and σemi × ∆λeff product (16.00 × 10−26 cm3) indicate a good gain property as well as a good gain bandwidth. Finally, the energy transfer coefficient (CD-A = 12.0 × 10−40 cm6/s) of cross relaxation (3H4, 3H6 → 3F4, 3F4) between Tm3+ ions is calculated. These results indicate that the prepared Tm3+-doped Bi2O3-GeO2-Ga2O3Na2O glass is a promising gain material for ~1.8 µm band solid-state laser applications.