Optimization of electrooptic and pieozoelectric coupling effects in tetragonal relaxor-PT ferroelectric single crystals

The electrooptic and piezoelectric coupling effects in tetragonal relaxor-based ferroelectric 0.62Pb(Mg1/3Nb2/3)O3-0.38PbTiO3 (PMN-0.38PT) and 0.88Pb(Zn1/3Nb2/3)O3-0.12PbTiO3 (PZN-0.12PT) single-domain crystals have been analyzed by the coordinate transformation. The orientation dependence of the electrooptic and half-wave voltage was calculated based on the full sets of refractive indices, electrooptic and piezoelectric coefficients. The optimum orientation cuts for achieving the best electrooptic coefficient and half-wave voltage were found. The lowset half-wave voltage is only 76 V for the PMN-0.38PT single-domain crystal. Compared to commonly used electrooptic crystal LiNbO3, tetragonal relaxor-PT ferroelectric single-domain crystals are much superior for optical modulation applications because of their much higher linear electrooptic coefficients and substantially lower half-wave voltages when the piezoelectric strain influence is considered.