The Study On The Erbium-doped Borosilicate Glasses Exhibiting Broadband Infrared Emission

Erbium-doped fiber amplifier (EDFA),utilizing the emission transition ⁴I_13/2→⁴I_15/2 of Er³⁺, is a key element of the 1.5μm window telecommunication system. The EDFA utilized at present is made of Er³⁺-doped silica glass, which shows narrow emission band at 1.5μm resulting in narrow gain spectra with bandwidth around 30nm. Due to rapid increase of information capacity and the need for flexible networks, there is urgent demand for optical amplifiers with a wide and flat gain spectrum in the telecommunication window. Therefore, the glass with a wide 1.5μm emission bandwidth of Er³⁺ ions has been paid a great attention. In this thesis, there are two subjects in my research. One is about of the characteristics of the 1.5μm infrared emission were investigated. The other is about of the search for Er³⁺-doped glass, which has a wide emission spectrum at 1.5μm, while has an excellent thermal and chemic stability. We prepared an oxide glass based on Bi2O3 oxide as host for Er³⁺ ions. The 1.5μm emission spectra are studied within the temperature from 11K to 300K. The spectral components of the transitions from the lowest and upper Stark levels of ⁴I_13/2 state to the ground state are separated and identified, respectively. The contributions of the spectral components to broadening of the 1.5μm emission band are discussed. An equivalent model of four-level system is presented to describe the spectral shape of ⁴I_13/2→⁴I_15/2 transition. The gadolinium doped and lutetium doped borosilicate glass system were prepared by the technique of high-temperature melting at different temperature and the formation range of glass are experimentally obtained, respectively. The thermal stability and broadband emission characteristics of the prepared glasses were discussed. Excellent thermal stability of the glasses has been demonstrated using differential thermal analysis. The maximum of full wave at half maximum (FWHM) in the gadolinium doped and lutetium doped borosilicate glass system are 70nm and 76nm, respectively. The optical parameters, such as the absorption and emission cross section, the J-O parameters Ωt(2,4,6) and radiative transition probabilities were calculated by using the theory of McCumber and Judd-Ofelt. The emission properties at 1.5μm of the samples are discussed with the product of full width at half maximum and stimulated emission cross section. It can be seen that the value of the FWHM×σe peak product in the prepared glass is more than those of silicate, germanate and phosphate glasses. The transparent glass ceramics around 1.5μm were obtained by the heat treatment for the previous glasses at the different temperature above its glass transition temperature (Tg), which show different emission spectral shapes from the corresponding glasses. The results indicated that radiative transition probability increase, while the FWHM increase, because the heat treatment bring on the crystallite. The lifetime of Er3+ in the glass ceramics is longer than that in the previous glasses by the measured time decay.