Absolute measurement of the quadratic nonlinear susceptibility of lithium niobate in waveguides

Efficiency measurements of second-harmonic generation in quasi-phase-matched lithium niobate waveguides yield a value for the nonlinear optical second-order susceptibility tensor element χzzz(2)(2ω;ω,ω)=d33=(−20.6±2.1)pmV in periodically poled, titanium-indiffused waveguides in congruent composition lithium niobate at room temperature for a fundamental wavelength of 1.52 μm. A special fringe structure in the tuning curves was observed and explained as an unique feature in quasi-phase-matched parametric processes.