GAN LINEAR ELECTROOPTIC EFFECT

Measurements of the linear (Pockels) electro-optical coefficient of wurtzite GaN are reported. The values for the electro-optic coefficients r(33) and r(31) are 1.91 +/- 0.35 and 0.57 +/- 0.11 pm/V at 633 nm, respectively, in agreement with extrapolations from measured second-harmonic generation coefficients (chi(33)((2)) = -20 +/- 6 pm/V and chi(31)((2)) pm/V) suggesting that the dominant contributions are electronic in origin. Measurements were performed using a Mach-Zehnder interferometer with LiNbO3 as a reference material. Piezoelectric effects were also observed. (C) 1995 American Institute of Physics.