Preparation And Research On Spectral Properties Of Bi-doped Silica-based Glasses

Since Fujimoto reported broadband infrared luminescence phenomenon of Bi-doped aluminosilicate glasses in 2001,broadband infrared luminescence of bismuth-doped glasses has attracted much attention. The gain bandwidth of rare earth ions doped fiber amplifiers (Er³⁺,Tm³⁺ and Pr³⁺) can not reach beyond 100 nm because of the 4f-4f electrons transition. Although Raman fiber amplifiers (FRAs) can overcome this problem, they require high-power consumption and more complicated structures. Bismuth-doped glasses show ultra-broadband luminescence covering 1000¹600nm wavelength region excited within 700～1100nm wavelength region. The full width at half maximum (FWHM) is about 300nm. And the fluorescence lifetime is about several hundred microseconds. The ultra-broadband luminescence of bismuth-doped glasses indicates that these glasses may be the potential gain medium for ultra-broadband optical amplification, tunable laser and ultra-short pulse laser source.Silica-based glass, which have excellent thermomechanical properties, can be used to produce optical fibers. The project of this dissertation is the research on bismuth-doped glasses with ultra-broadband luminescence over the optical communication window. The effects of Al2O3,Y2O3 and La2O3 on the ultra-broadband luminescence and the spectral properties of Yb-Bi energy transfer have been studied. And finally the ultra-broadband infrared luminescence of the silica-based glasses was successfully realized and we got many significant results. Main achieved results are listed as follow:(1) The critical concentration of Bi2O3 in bismush-doped silicate glasses is 2².5mol%;The FWHM is 182 nm,the lifetime is 465μs,and the stimulated emission section is 4.11×10-20cm2 from the glass sample of 65SiO₂·10Al₂O₃·25CaCO₃·2Bi₂O₃.(2) The role of Al₂O₃ and Y2O3 played in the near infrared emission of bismuth-doped silicate glass is dispersant,and codoping Al³⁺,Y³⁺ can enhance the near infrared emission. The formed [AlO4] can effect the formation of Bi-related ions of near infrared emission. Codoping La³⁺ can reduce the Absorption and near infrared emission of bismuth-doped silicate glass, then La2O3 is not a good dopant of bismuth-doped materials.(3) The near infrared luminescence can be observed from the Yb-Bi-codoped silicate glasses when pumped with 808 nm and 976 nm LD. The emission strength excited in 976 nm is muth weaker than that in 808 nm, so we can say that the near infrared emission from Yb-Bi-codoped silicate glass can be attributed to Yb-Bi energy transfer, which can be provened in the measurment of fluorescence lifetime. The Yb-Bi codoped silicate glass exhibits～30 times stronger near infrared emission than Bi-doped silicate glass. Yb2O3 is a effectively sensitizer which can enhance the near infrared fluorescence of bismuth-doped silicate glasses.