EXPERIMENTAL-STUDY AND MODELING OF DOUBLE -REFRACTION ATTENUATION OF TYPE-II 2ND-HARMONIC GENERATION IN KTIOPO4

The walk-off attenuation of the second harmonic generation (SHG) effic iency is governed by the crystal length and by the beam waist radius a nd location inside the crystal. We present an experimental study for t ype II SHG concerning both weak and strong focusing. We particularly s tudy 1.064 mu m SHG in KTiOPO4 (KTP). The optimum focusing conditions and saturation length are well described by the gaussian model, on the contrary of plane waves approximation. The saturation of the associat ed angular acceptance is clearly put in evidence for the strong focusi ng cases.