Linear electro-optic effect of 0.88Pb(Zn_1/3Nb_2/3)O₃-0.12PbTiO₃ single crystal

The linear electro-optic (E-O) coefficients of poled 0.88Pb(Zn_1/3Nb_2/3)O₃-0.12PbTiO₃ single crystal were characterized using an automated scanning Mach-Zehnder interferometer and the senarmont compensator method at room temperature. They were obtained at a wavelength of 632.8 nm: r₃₃ = 134 pm/V, r₁₃ = 7 pm/V, r₅₁ = 462 pm/V, and r_c = 131 pm/V respectively and the refractive indices: n_e = 2.57 and n_o = 2.46. The large r₅₁ coefficient compared with r₃₃ is caused by the high dielectric constant at perpendicular to the polar-axis compared with the dielectric constant along the c-axis. Comparison with the quadratic E-O coefficients measured at near and above the Curie temperature suggests that the values of the quadratic E-O coefficients measured earlier may be smaller than the intrinsic ones due to the influence of micro-polar regions. The development of an automated scanning Mach-Zehnder interferometer, which is less susceptible to the errors caused by the laser intensity fluctuation and drafting in the optical path length in the system, is also described.