Consecutive quasi-phase-matched generation of the third harmonic of the radiation from an Nd:YAG laser in a periodicaly poled Y:LiNbO3crystal

Consecutive generation of the third harmonic (i.e. generation of radiation with the doubled frequency followed by frequency summation) radiation from a Q-switched Nd:YAG laser (λ = 1.064 μm) was observed in a Y:LiNbO3 crystal polarised periodically along the z axis. The modulation period of the nonlinear susceptibility was ~ 60 μm. The second and third harmonics of the radiation were generated respectively in the ninth and thirty-third quasi-phase-matching orders.