Yttrium Orthosilicate single crystal (Y₂SiO₅)  is a good optical and laser material. doped with the elements of  rare earth or transition-metal, it has been widely used in the laser and optical techniques, such as the laser host material for near IR, passive Q-switch, scintillation detectors. Especially, the samples of Y₂SiO₅ doped with Praseodymium (Pr), Europium (Eu) or Cerium (Ce) were used in the experiments of “light speed reduction” and “spectral hole burning” recently and very good results were achieved (for example, the very low light speed of 45m/s from the sample of Pr:BSO). The YSO crystal will be an important material for the research and development for some nonlinear optics, quantum computing , optical information storage topics because its excellent features