Effect of Al(PO3)3 content on physical, chemical and optical properties of fluorophosphate glasses for 2 μm application

The effect of Al(PO3)3 content on physical, chemical and optical properties of fluorophosphate glasses for 2 μm application, such as thermal stability, chemical durability, surface hardness, absorption spectra and emission spectra, is investigated. With the increment of Al(PO3)3 content, the thermal stability characterized by the gap of Tg and Tx increases first and then decreases, and reaches the maximum level containing 5 mol% Al(PO3)3 content. The density and chemical durability decrease monotonously with the introduction of Al(PO3)3 content increasing, while the refractive index and surface hardness increase. Above properties of fluorophosphate glasses are also compared with fluoride glasses and phosphate glasses. The Judd–Ofelt parameters, absorption and emission cross sections are discussed based on the absorption spectra of Tm-doped glasses. The emission spectra are also measured and the 1.8 μm fluorescence of the sample is obvious indicating that it is suitable to 2 μm application.