Electro-optic coefficients measurement based on a multiple-reflection Mach-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 [Θ=2mπ and Θ=(2m+1)π]. Numerical simulations with congruent lithium niobate show that angular deviations below 0.1 limit EOC errors to <2.5%. Experiments using a He-Ne laser achieve <1% variance in γ₁₃ and γ₃₃, confirming theoretical predictions. The approach also enables frequency-resolved EOC characterization, offering a simple, high-precision solution for MR suppression in optical metrology.