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

The effect of terbium gallium garnet ($TGG$) crystal length on 1064 and 532 nm output powers and beam quality of a unidirectional ring ${Nd:YVO}_4$ laser is investigated. In the case of 1064 nm (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 532 nm. It was found that in a 532 nm laser, higher laser efficiency and small beam quality degradation can be achieved by increasing the $TGG$ crystal length leading to a 5.7 W green laser with 27 W pump power. The power stability and beam quality were 0.8% for 30 min and less than 1.3, respectively. (paper)