The effects of TGG crystal length on output power and beam quality of a unidirectional ring Nd:YVO4 laser with and without second harmonic generation

Abstract

The effect of terbium gallium garnet (TGG) crystal length on 1064 and 532nm output powers and beam quality of a unidirectional ring Nd: YVO4 laser is investigated. In the case of 1064nm (without nonlinear crystal), the laser output power without considerating the effect of TGG crystal was computed theoretically. Then three TGG crystals with different lengths were placed in the laser setup one by one. A systematic decrease in output power was observed by increasing the TGG crystal length. The experiment was repeated in the case of 532nm. It was found that in a 532nm laser, higher laser efficiency and small beam quality degradation can be achieved by increasing the TGG crystal length leading to a 5.7W green laser with 27W pump power. The power stability and beam quality were 0.8% for 30min and less than 1.3, respectively.