Measurement of second-harmonic optical susceptibility using Rayleigh scattering

We report a simple method to measure relative second-harmonic optical susceptibilities of crystals by use of Rayleigh scattering. We use two crystals with fixed alignments: one is a phase-matched crystal with varying degrees of phase matching, which serves as a reference point of the phase relationship and a source for the second-harmonic beam to be incident on the sample crystal, and the other is a sample crystal for measurement. The second-harmonic signals generated from each of the two crystals are superposed in the sample crystal to give Rayleigh scattering at the second-harmonic frequency, the analysis of which can determine the relative values of the second-harmonic optical susceptibilities of the sample crystals. We have applied this method to obtain d₁₄ (KDP)1.8 d₃₆ (KDP), d₃₆ (ADP)1.1 d₃₆ (KDP), d₃₁ (KTP)15 d₃₆ (KDP), d₃₂ (KTP)13 d₃₆ (KDP), where d₃₆ of KDP crystals was taken as a reference.