Effects of crystal parameters on power and efficiency of Nd : YVO4 laser in-band pumped by 914 nm laser

To overcome the main drawback of poor pump absorption of Nd : YVO4 lasers in-band pumped at 914 nm, three possible methods of higher temperature, longer crystal length and higher doping concentration were experimentally studied. A Nd : YVO4 laser operating at 914 nm was used as high beam quality, narrow line-width pump source to make the measurement of pump absorption accurate. Four different Nd : YVO4 crystals were used as gain mediums to investigate the effects of crystal parameters. We found that heating the crystal effects differently on output power and overall efficiency when crystal doping concentration changed. To improve the pump absorption and meanwhile achieve high efficiency, longer crystal with proper doping concentration and pump feedback should be adopted instead of highly doped crystal.