Accurate Measurements of the Magnitude and the Relative Sign of Optical Nonlinear Susceptibility in Ferroelectric Crystals

Abstract

The Maker fringe method has been employed to determine the magnitude of the nonlinear optical susceptibility accurately in ferroelectric NaNO₂ as well as the relative sign in NaNO₂ and Ca₂Sr(CH₃CH₂CO₂)_b, both by rotating a plane-paralleled sample and by sliding a slightly wedge-shaped one. An analysis of the Maker fringe in nonabsorbing biaxial crystals has also been made, including corrections of the birefringence effect. As a result, we have obtained d₃₁=0.23±0.02, d₃₂=5.2±0.7, d₃₃=0.30±0.02, d₁₅=0.23±0.02 and d₂₄=5.2±0.7 in NaNO₂ relative to d₁₁ in quartz for a fundamental wavelength 1.06μm, and d₃₁•d₃₃<0, d₃₂•d₃₃>0, d₂₄•d₃₃>0 in NaNO₂ and d₃₁•d₃₃<0 in Ca₂Sr(CH₃CH₂CO₂)₆. Further, the domain effect, the experimental errors and a comparison of the sliding method with the rotating method are discussed.