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 () crystal length on 1064 and 532 nm output powers and beam quality of a unidirectional ring laser is investigated. In the case of 1064 nm (without nonlinear crystal), the laser output power without considerating the effect of crystal was computed theoretically. Then three crystals with different lengths were placed in the laser setup one by one. A systematic decrease in output power was observed by increasing the 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 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.