STUDY OF ACOUSTO-OPTICAL PROPERTIES OF CRYSTALS USING MACH–ZEHNDER INTERFEROMETER
Keywords:
Keywords. Acousto-optics; Mach–Zehnder interferometer; Lithium niobate; Lithium tantalate; Langasite; Photoelastic coefficient; Figure of merit; Anisotropy.Abstract
Abstract. This paper presents a comprehensive investigation of the acousto-optic (AO) properties of lithium niobate (LiNbO₃), lithium tantalate (LiTaO₃), and langasite (La₃Ga₅SiO₁₄) crystals using the Mach–Zehnder interferometric technique. The method enables precise measurement of phase modulation and effective photoelastic coefficients (peff), allowing the evaluation of the acousto-optic figure of merit (M²) and its anisotropy. Experimental measurements were performed in the frequency range of 400–1200 MHz using a helium–neon laser (λ = 633 nm). The results reveal a strong dependence of AO efficiency on crystal orientation, confirming theoretical predictions based on the Dixon–Cohen model. Lithium niobate exhibited the highest M² value, indicating its superior potential for acousto-optic modulators and deflectors. The findings validate the reliability of the Mach–Zehnder interferometric approach for characterizing anisotropic acousto-optic phenomena.
