Electro-optic coefficients measurement based on a multiple-reflectionMach–Zehnder interferometer

Multiple-reflection (MR) effects in flat optical crystals can cause significant errors in electro-optic coefficient (EOC) measurements. We present a Mach-Zehnder interferometer method that incorporates MR modeling and suppresses its influence by selecting specific incidence angles [<i>Θ</i>=2<i>m</i><i>π</i> and <i>Θ</i>=(2<i>m</i>+1)<i>π</i>]. Numerical simulations with congruent lithium niobate show that angular deviations below 0.1 limit EOC errors to <2.5<i>%</i>. Experiments using a He-Ne laser achieve <1<i>%</i> variance in <i>γ</i>₁₃ and <i>γ</i>₃₃, confirming theoretical predictions. The approach also enables frequency-resolved EOC characterization, offering a simple, high-precision solution for MR suppression in optical metrology.