ABSOLUTE MEASUREMENT OF QUADRATIC NONLINEARITIES FROM PHASE-MATCHED 2ND-HARMONIC GENERATION IN A SINGLE KTP CRYSTAL CUT AS A SPHERE

We determine within an accuracy of similar to 10% the absolute magnitu de of the quadratic effective coefficients of types I and II phase-mat ched second-harmonic generation from conversion efficiency measurement s in a single nonlinear crystal cut as a sphere. The agreement is good with measurements performed in thin parallelepipedal samples. The mat erial studied is KTiOPO4, for which improved Sellmeier equations are g iven. (C) 1997 Optical Society of America.