• laser
• slope efficiency
• spectroscopy
• μ-PD

The people have known and used crystals for thousands of years, such as jewels, minerals and natural quartz, and at the same time they also started the polycrystal growth such like the salt production in the sunshine and the Chinese alchemy. The formation of the crystal in nature and the preparation of the crystals by artificial is called Crystal growth.
Single crystal is defined by long-range atomic order extending over many atomic diameters, and having a repetitive structure, so a usual characteristics of single crystals are non deformability and mechanical strengthens.The growth of single crystals is both scientifical and technological process. There are two major techniques for growing single crystal, namely, the growth from solutions and the growth from melts. The very important growth method to get single crystals of given material is by solidification of its own melt, which is called crystal growth from the melt.
Since their birth in 60 years ago, lasers have evolved from an exotic laboratory technology to become tools daily used in a variety of applications: medicine, telecommunication, industry and scientific research. Due to the large number of applications, the research to get different laser materials is very critical. The rare earth ions doped single crystals are the key laser materials. In this work we are interested in growing some rare earth ions doped single crystal fibers during my Ph.D work. We grew these crystal fibers by the Micro-Pulling-Down technique (μ-PD), which is a useful method to grow the fiber crystals. In the thesis, I will show the properties of the Yb3+, Tm3+, Ho3+, and Er3+ doped crystals, with the analysis of the spectroscopy and the laser experiments.
For the Yb:LuAG crystal, we get 23 mW and 1030 nm laser output with the slope efficiency 32%, the results are much better than the ones reported before. We measured the spectroscopy of the Tm:LuAG, and analyse the fluorescence spectrum with Judd-Ofled method. The Ho:LLF crystals were obtained up to 7.1 W and 6.2 W laser output with the slop efficiency 41.4% and 27.7% in different length samples experiments. It is the first time of laser output for the Ho:LLF fiber grown by μ-PD technique.