Study On The Broadband Near Infrared Luminescent Properties Of Bismuth Doped Glasses

With the rapid development of telecommunication technology and computer network, optical fiber transmission technology with super-high-speed and super-high-capacity is demanded. Recently, great progress has been achieved in the OH elimination of silica fibers. As a result, the telecommunication transmission window has been extended to the range from 1.2 to 1.7μm. However, due to the intrinsical charcteristics of f-f electronic transitions of rare-earth ions, the conventional rare-earth-doped fiber amplifiers only can work in certain bands. For examples, erbium (Er)-doped fiber amplifiers provide gain in the C band (1530-1565 nm), L band (1570-1605 nm) and S band (1450-1520 nm). The narrow gain region sets limitation for the numbers of signal channel, which makes serious trouble for super-high-capacity information transmission. If optical amplification can be realized by a single broadband fiber amplifier in all optical telecommunication waveband, a new revolution can no doubt be anticipated in the future data transportation system.This thesis provides a comprehensive review on the luminescent characteristics of rare-earth, transition-metal, semiconductor quantum dot and main-group ions doped materials, gives an overview of the recent progress and problems. Investigations are carried out on new Bi activated broadband near-infrared luminescence materials. We investigate the origin of the broadband near-infrared luminescence of Bi doped glasses by adjusting the glass composition and gamma-ray induced effect. A series of important conclusions and innovative results with practical significance were obtained.We report on the visible and near-infrared luminescent properties of Bi-doped sodium borosilicate glasses. The emission intensity at 420 nm due to the transition of Bi3+ decreases with increasing B2O3 concentration. Due to the so-called boron anomaly in these glasses, the emission intensities of both the visible emission at 618 nm ascribed to the transition of Bi2+ and the near-infrared emission at 1340 nm ascribed to the transition of Bi+vary nonmonotonically with the [B2O3]/[Na2O] ratio. We have proposed a mechanism that suggests Bi+ to be responsible for the near-infrared luminescence, and [BO4] units play an important role for stabilizing Bi ions with low valence state in glasses. The infrared emission is quite sensitive to glass composition and excitation wavelength.We also studied the evolution of the luminescent properties of Bi doped nanoporous silica glass as a function ofγ-ray irradiation. Theγ-ray is employed to induce multiple active centers of bismuth in an interesting "tolerant" host—nanoporous silica glass. We found the valence of bismuth ion have changed after irradiation. We also found two new broadband luminescence centers at near infrared region after irradiation, band at 940 nm and 1258 nm, respectively. When the sample was treated at argon atmosphere, superbroadband near-infrared luminescence with full width at half maximum of 375 nm was observed after irradiation. The luminescence mechanism was also discussed and the ESR results proved that infrared luminescence was originated from the Bi+ion.