Growth and fluorescence measurements of neodymium: Yttrium Aluminum Garnet, neodymium fluoride, Ti: Sapphire, ytterbium fluoride and mixture of neodymium fluoride with ytterbium fluoride thin films

摘要

The main objective of the present work was to fabricate and find evidence of fluorescence in the optical films of some well established laser materials and as well as some other new materials have also been probed. Materials such as Nd:Yttrium Aluminum Garnet (Nd:YAG), Ti:Sapphire, NdF_3 and YbF_3 were deposited on BK7 type optical glass, fused silica (Suprasil), Sapphire and YAG substrates by conventional electron beam evaporation processes. In case of Nd:YAG, the films were prepared by using pure single crystals of Nd: YAG as evaporation material. Samples with higher Nd content were also prepared in order to enhance the absorption in the film at the pump wavelength. A theoretical analysis for the lasing action in the Nd: YAG film has also been made and parameters like gain, threshold population inversion, threshold power etc. have been calculated for the realisation of laser action in thin films. In case of Ti:Sapphire, the films were prepared by an Ion Beam Sputtering process. It has been demonstrated that fluorescence can be observed in Electron-beam deposited films of Nd: YAG and NdF_3 when pumped with a diode laser at 802 nm. The maximum peak emission was observed at 1066 nm in case of Nd:YAG and 1046 nm in case of NdF_3. ATi:Sapphire sample has also been excited using an Nd:YAG laser at 532 nm. Here a broad band fluorescence spectrum was observed. Films of YbF_3 and YbF_3+NdF_3 (co-deposition) prepared by Electron Beam Evaporation were also studied.