Performance of Nd:YVO4 laser at various doping levels

Abstract

The aim of this research to study the performance of the gain medium Nd:YVO4 laser crystal at various doping level. Diode laser centered at 808 nm was employed as an optical pumping source. The concentration under studied are including 0.5 at %, 1.0 at % and 1.5 at % neodymium ion doped into vanadate YVO4 crystal. The length for the three tested crystal is remained the same as 1 mm. The Nd:YVO4 crystals were pumped using end-pumping Technique. The output of the Nd:YVO4 crystal after being pumping was detected using spectrum analyzer, power meter and CCD video camera. The Nd:YVO4 laser beam producing line centre at 1063.98 nm with bandwidth of 1.15 nm. The beam spot of the light produced from each crystal is recorded using CCD camera. In general the beam spot is increasing with respect to the pump power. The slope conversion efficiency for 0.5 at % Nd+3 ion doped YVO4 crystal is 4.8 % with threshold power of 1404 mW. No crack is found with this crystal. In contrast the 1.0 at % Nd+3 doped in YVO4 crystal, suffering severe damage via long cracking on the surface. Thus the performance of the crystal is found the lowest among the three testing crystal. The slope conversion is 5.6 % with threshold power of 426 mW. The Nd:YVO4 crystal with doping level 1.5 at % having the optimum slope efficiency of 8.8 % with threshold power of 773 mW. However, this crystal also experience thermal stress causing cracking on the surface of crystal. As conclusion, the small concentration will be long lasting gain medium although the performance may not that good as compared to 1.5 at % Nd:YVO4 crystal.