Research On The Emission Character Of Rare-earth Doped Silicate Glass

Silicate glass especially silica glass have very high chemical stability, mechanical strength, light transmittance and large thermal damage threshold. The transmission wavelength is from0.3μm to2μm. Therefore, they are the best matrix for doped emission glass and active fiber. Howerver, the doping concentration of reactive ions is hard to improve. The rare-earth is easily clustered in silica glass, even there is only several hundred ppm of them. In this dissertation, we studied the cluster behavior of rare-eatrh ions and the way to enhangce emission in silicate glass; and prepared emission silica glass and active fiber by sintering the doped nanoporous silica glass.In the chapter I, the rare-earth emission properties and emission glass are introduced fistely; then discussed the properties, prepare and develop of nanoporous glass; thirdly explained the properties of double clad fiber and the preparation of nanoporous glass fiber. In the chapter II, some theories about emission glass are described.In this dissertation, there are mainly three parts. Part I study and tailor the cluster of rare-earth ions. Part II study and prepare the emission nanoporous silica glass. Part III study and prepare the double clad fiber, which core is made by doped nanoporous glass. The tailoring of clusters of active ions in silicate glass is mainly by codoping inert emitting ions, such as Ca2+、Al3+、 Y3-、La3+、 Gd3+. Besides, we obtained tri-color emission glass, white emission glass, broadband emission glass and near infrared emission glass by energy transfer.It is easily to improve the doping concentration and suppress the produce of clusters in multi-component glass, due to the rich of non-bridging oxygen. Howerver, it is very hard to break the silicon-oxygen tetrahedron for doped rare-earth ions in silica glass. The complete netework has no extra oxygen for active ions and the cluster is inevitably. Therefore, new ideas have been needed to improve the doping concentration without clusters in silica glass. Fortunately, the nanoporous glass fulfills the requests, which has very large specific surface area. The nano pore structures break the silicon-oxygen network and produce enough non-bridging oxygen for active ions. The nano pore structures can also separate the active ions. Therefor, we prepared nanoporous glass with lOnm pores and200m2/g specific surface area. Then we obtained tri-color emission glass, white emission glass and near infrared emission glass, which component is very close to the silica glass.There are still some difficults to prepare active fiber with high doping concentration, high absorption coefficient and large core. In the exciting technology the core have large inhomogeneity and relatively small dissolving capacity of rare-earth ions. Besides, the background loss is large and the size of core is small. It is said that, the nanoporous glass rod as core not only can be made very large in diameter and length, but also has very uniform pore structure and high doping concentration. Given the properties of the nanoporous glass, this material can be used to solve the above mentioned problems. Therefore, we prepared double-clad fiber with Yb doped nanoporous glass as core and obtained laser output.