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In this work, we study the mechanisms of X‐ray induced darkening in the Dy/Al/P co‐doped silica glasses at visible wavelengths and explore the role of P/Al ratio played in the enhancement of irradiation resistance. The absorption, emission spectra and lifetime, Raman, and electron paramagnetic resonance spectra of pristine and irradiated Dy‐silica glasses as a function of P/Al ratio were measured and analyzed. The Si‐related defects (Si‐E′ and non‐bridge oxygen hole center), Al‐related defects (Al‐E′ and Al‐related oxygen hole center), P‐related defects (P‐OHC and P2), and Dy2+ ions were studied and analyzed. Results demonstrate that increasing P/Al is efficient to suppress the photodarkening in Dy‐silica glasses at visible wavelengths. Results imply that Dy‐silica glasses with P/Al > 1 may be a promising candidate for efficient visible fiber lasers operated at around 575 nm wavelength. [ABSTRACT FROM AUTHOR]

In this work, we revealed the possible mechanisms of the photodarkening in Pr3+ ions singly doped and Pr3+/Ce3+ co‐doped silicate glasses and fibers induced by X‐ray and 488‐nm laser radiations and studied the role of Ce3+ in increasing radiation resistance in Pr3+‐doped silicate glasses and fibers. The absorption, emission, electron paramagnetic resonance (EPR), radiation induced attenuation spectra, and X‐ray photoelectron spectroscopy (XPS) of Pr3+ singly doped and Pr3+/Ce3+ co‐doped silicate glasses before and after X‐ray radiation were measured and analyzed. The fluorescence intensity and photoinduced attenuation of Pr3+ singly doped and Pr3+/Ce3+ co‐doped silicate fibers at visible wavelengths pumped by 488‐nm laser were measured and analyzed. The influence of Ce3+ ions co‐doping on the spectroscopic properties of Pr3+ ions as well as the radiation‐induced defects in silicate glasses was studied. Results demonstrate that both X‐ray and 488‐nm laser radiations will induce photodamage in Pr3+ ions‐doped silicate glasses and fibers. Co‐doping Ce3+ (by up to 1 mol%) is efficient to suppress the darkening induced by both X‐ray and 488‐nm laser radiations without influence on the luminescence behavior of Pr3+ ions in silicate glasses and fibers. Our studies demonstrate the promising potential of Pr3+/Ce3+ co‐doped silicate glasses for visible lasing applications. [ABSTRACT FROM AUTHOR]

In this work, we systematically study the spectroscopic properties of Tb3+/Dy3+ co‐doped phosphate glasses in the visible spectral region and explore the sensitization role of Dy3+ in the enhancement of visible fluorescence of Tb3+ ions. Judd‐Ofelt parameters Ω2 and Ω4/Ω6 of the phosphate glass as host for Tb3+ are calculated as 21.60 × 10‐20 cm2 and 0.73, respectively, based on the measured spectral absorption. Multiple energy transfer (ET) routes from Dy3+ to Tb3+ and their efficiencies are characterized, and the enhanced fluorescence properties of Tb3+ are investigated, including the emission spectral strength and the spontaneous emission lifetime as functions of Dy3+ doping concentration. The efficient nonradiative ET processes between Dy3+ and Tb3+ allow a moderate concentration level of Tb3+ to achieve favorably stronger spectral absorption at blue and ultraviolet wavelengths. Tb3+/Dy3+ co‐doped phosphate glass shows promising potential for phosphors and lasing operation at visible wavelengths. [ABSTRACT FROM AUTHOR]