The Effect Mechanism Of Local Environment On The Near Infrared Luminecence Of Bi-doped Glasses

With the development of the optical communication system, there are two methods to achieve the super high capacity of information transmission. One is to improve the speed of the information transmission.The other is to broaden the spectral region of the information transmission. The transmission rate of modern commercial fiber has been over 10 Tbit/s, and the velocity can over 100 Tbit/s in the laboratory. It has been a vast succeeds in the optical communication and information transmission system, but the capacity requirement of the information transmission is still increasing. The demand of the transmission rate will attain to 1015 bit/s in the next 20 years. Therefore, expanding spectral region of the information transmission becomes an urgent problem in the optical communication system.The low loss area of quartz fiber can cover the ultra wideband near infrared wave region from 1.0 to 1.8μm, and the less than 0.4 dB/km transmission loss ranges is from 1.3 to 1.7 μm. However, confined by the f-f transition of rare earth ions, the gain bandwidth of the rare earth doped amplifier is difficult to cover the whole optical communication windows. The super broadband near infrared (NIR) luminescence of bismuth (Bi) ions can almost cover the whole of the low loss area in 1.0-1.8μm, which makes "to achieve the entire signal amplification in the optical communication system by using only one fiber and one pump source" to be come ture. Therefore, it has positive significance in studying optical properties of Bi doped glasses for promoting the practical application.However, the origin of the near infrared luminescence is controversial till now, which suppresses the development of the Bi-doped fiber laser and amplifier. Much more foundational researches need to be done to clear the mechanism of the Bi NIR emission, and to improve the efficiency of Bi-doped fiber laser and fiber amplifer, and then the devices can be used in reality.In this work, the influence of environmentes to the NIR luminescence is studied, the mechanism of Bi NIR luminescence is analysised, and the effect of enviromnentes to Bi NIR luminescence is discussied. All of these can prove theory support for the practical application of Bi-doped fiber devices. The detailed contents and results are listed as follows:1. The modulation of optical basicity to the NIR luminescence of Bi is investigated. Samples with different optical basicity are prepared by melt-quenching method. It is found that the NIR luminescence is enhanced with the decreasing optical basicity, while the NIR emission is decreased with the increasing optical basicity.2. The modulation of glass structure to the NIR emission of Bi is investigated. In germanate glasses, along with the increase of optiacal basicity, the NIR emission of Bi shows abnormal phenomenon, which can not be interpretated by the theory of optical basicity. The abnormal phnemenon should connect with the glass structure according our research. The compared experiments between silicate and germanate glasses further verify the above deduction. Accompanied with the change of optical basicity, there are no abvious structure changes in silicate glasses, the NIR emission of Bi can be explained by the theory of optical basicity; however, there are distinct structure transfoms in germanate glasses, the NIR luminescence intensity of Bi convert with the glass structure.3. The modulation of ion exchange to the NIR emission of Bi is investigated. The Ag-Na ion-exchanged samples are prepared by dipped the glasses into different molten baths of AgNO3/NaNO3. After Ag+ for Na+ ion exchange, the NIR emission of Bi is ehanced. After the heat treatment, the NIR emission of Bi is further enhanced. After Cu+ for Na+ ion exchange, the NIR luminescence of Bi is also enhanced. After the heat treatment, the NIR emission of Bi is tampered NIR emission.4. The modulation of co-doped rare earth to the NIR emission of Bi is investigated. The co-doped rare earth can modulate the intensity, bandwidth and shape of Bi NIR emission. Therefore, co-doping rare earth can modulate the profile of the NIR luminescence of Bi in glasses, and achieve more gain flattening of the NIR luminescence of Bi.