Fabrication Of Bi-doped Materials And Research On Mechanism And Enhancement Of Near-IR Luminescence

Since Fujimoto and his co-workers reported a novel near infrared (NIR) emissionfrom bismuth-doped silicate glasses, which have drawn much attention for its potentialapplication in ultra-broadband optical fiber amplifiers. However, there are two mainfactors which restrict it’s further investigation and application:(1) the origin of the IRluminescence is unclear yet and still remains highly debated;(2) the NIR fluorescenceintensity of Bismuth is too weak to be apply in more fields.Therefore, the mechanism ofnear-IR emission and how to enhance the emission intensity became a key challenge to beexplored.The main topics of this thesis are the nature of NIR luminescence and the methods toenhance the NIR emission. The effects of glass component, melting parameter, andpumping wavelength on the spectral properties of Bi-doped glass have been investigated.Based on those results, the mechanism of Bi-related near-infrared luminescence wasproposed. A method for improving the spectral properties of Bi-doped glasses by utilizingthe energy transfer from Yb3+was also proposed. The main content of the thesis includes:(1) Effects of co-doping of alkaline earth ions (Mg2+、Ca2+、Ba2+), reducing agent (Sipowder) and oxidizing agents (CeO2、Nb2O5) on the spectral properties of Bi-dopedglasses have been investigated and analyzed by optical basicity theory. Therefore,near-infrared luminescence from Bi-doped glass should be ascribed to the active centersrelated to bismuth ions with low valence, most likely Bi+.(2) Appropriately heat-treatment during the preparation of LAS (Li2O-Al2O3-SiO2)glass-ceramics will enhance the NIR emission intensity and broaden the full width at halfmaximum (FWHM). The dependce of NIR emission intensity on the heat-treatmenttemperatures could be interpreted by utilizing optical basicity theory and confirm that theorigin of NIR emitting is derived from low valence Bi ions.(2) The energy transfer from Yb3+to Bi active ions is investigated in silicate glasses.The highest energy transfer efficiency is about68.2%when the ratio between Yb2O3andBi2O3reach the optimal20:1, which will provide a set of basis for the subsequentresearch of energy transfer in Yb/Bi doped fiber.