Accurate measurement of quadratic nonlinear-optical coefficients of gallium nitride

We have determined all the three independent components of quadratic nonlinear-optical coefficients of GaN by highly accurate Maker-fringe measurements on high-quality bulk samples combined with theoretical analysis taking account of the multiple-reflection effects in slightly misoriented optically anisotropic samples. Especially, the d33 coefficient is determined with sufficient accuracies for the first time, to our knowledge, by using (112¯0)-oriented samples. The obtained values of quadratic nonlinear-optical coefficients are d31=2.5±0.1 pm/V, d15=2.5±0.1 pm/V, and d33=−3.8±0.2 pm/V at the fundamental wavelength of 1.064 μm.