Broadband Luminescence Properties Of Bismuth-Doped Glasses

Fujimoto et al discovered broadband infrared luminescence from bismuth-doped aluminosilicate glasses in 2001, since then broadband infrared luminescence of bismuth-doped glasses has attracted much attention. The infrared luminescence of the Bi-doped glasses locates at optical communication wavelength region, and the optical properties including band width, fluorecent lifetime, and tunablility are better than those of erbium-doped glasses which have been used in optical fiber communication system. Therefore, the bismuth-doped glasses have great application prospect. Once bismuth-doped fiber amplifier becomes true, great changes will happen in the optical fiber communication.In this thesis, bismuth-doped silicate glasses were prepared and their near infrared broadband luminescent characteristics were" investigated. By studying glasses with different compositions, we have realized luminescence with broad band and long lifetime, as well as large stimulated cross section. Also, we discussed the luminescent mechanism for the near infrared luminescence. We believe that our experimental efforts and theoretical research will be useful for the further exploration in this field.In Chapter 1, the purpose and significance of the research on infrared luminescent materials were introduced, and optical properties of glasses doped with rare earth ions were reviewed. Then we introduced luminescent characteristics of transition metal ions and their limitation. Finally, recent research progress of bismuth-doped materials was presented.In Chapter 2, we mainly introduced the history of optical fiber communication, basic structures and characteristics of various optical amplifiers. We also presented the luminescent characteristics of bismuth ions-doped materials with some different valence states.Experimental processes and related theories were simply introduced in Chapter 3. The experimental processes include sample preparation and measurement of various spectra. The related theories include calculation method for absorption cross section,stimulated cross section as well as optical basicity theory.In Chapter 4, bismuth and nickel co-doped barium aluminosilicate glasses, bismuth-doped barium aluminosilicate glasses which were melted at different temperatures and different time, bismuth-doped lithium aluminosilicate glasses and glasses with composition of MO·Al₂O₃SiO₂·Bi₂O₃(M²⁺=Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺ and Pb²⁺ ) were investigated. It showed that absorption and fluorescence spectra vary with nickel content in silicate glasses. The luminescence locates at 1330nm with full width at half maximum (FWHM) about 180nm. The intensity of infrared luminescence decreased with increasing nickel content, which indicated that nickel is harmful to the bismuth-doped optical amplification. So we must avoid nickel ions when we prepare bismuth-doped glasses. Although the valence state of bismuth ions resulting in infrared luminescence is still controversial, we suggest that the infrared luminescence originates from Bi⁺ based on our results. In other glasses samples, we also realized infrared broadband luminescence. We calculated the stimulated cross section of bismuth-doped lithium aluminosilicate glasses and glasses with composition of MO·Al₂O₃SiO₂Bi₂O₃ (M²⁺=Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺ and Pb²⁺). By comparing with Ti: Al₂O₃, we concluded that these materials have great potential for optical fiber amplifiers and tunable lasers.The main research results were summarized in Chapter 5.The last chapter presented the existed problems should be solved for practical applications and further research direction.