Ordinary and extraordinary refractive indices for $AlxGa1−xN$ epitaxial layers

Dispersion of the ordinary and extraordinary indices of refraction for wurtzite $AlxGa1−xN$ epitaxial layers with $x=0.00,$ 0.04, 0.08, 0.11, and 0.20 in the range of wavelengths $457<λ<980 nm$ were measured via a prism-coupled waveguide technique. The quantitative accuracy of x is $±10%$ and the accuracy of the refractive indices is $∼±0.01.$ The dispersion is found to be well described by a 1st-order Sellmeier dispersion formula. A simple functional form is presented that allows calculation of the refractive indices as functions of x and λ.