Abstract:We have investigated the crystal orientation dependence of optical properties in InxGa1−xN/GaN multiple quantum wells. The spectral peaks and intensity of the microphotoluminescence signal for different crystal orientations were found to have six-fold symmetry. Quite interestingly, the refractive index, obtained from the interference pattern, also varies with the crystal orientation. The 60° periodic anisotropy of electronic transitions as well as optical parameters was interpreted in terms of the Pockels effect induced by the strong built-in field in nitride heterojunctions. The linear dependence of the change of the refractive index on electric field is consistent with the prediction of the Pockels effect. Our result provides an alternative solution to improve the designs of photonic and electronic devices based on nitride semiconductors.