Contents 1. Introduction
From crystallography of YAG we know that there are 24 tetrahedral and 16 octahedral sites in the unit cell of the garnet structure. doped crystals are interesting as gain materials for tunable solid state lasers in the infrared spectral region between 1100 to 1900run. The spectroscopic characterization of the transition ( symmetry) of the ion in YAG is presented considering the crystal field splitting and phonon coupling. With its near-infrared (NIR) broad emission bandwidth from 1.2 to 1.6 that fall in the low loss window of silica fiber, it is quite attractive to adapt it as a broadband amplifier for telecommunications [1].
