Effective index is a refractive index which depends not only on the wavelength but also on the mode in which the light propagates. It depends on the structural shape of the waveguide, mainly on its physical dimensions which restrain the light propagation introducing the optical confinement. For this reason a specific method have been developed to evaluate the effective refractive index of waveguides made by a particular wide gap III-Nitrides InxGa1-xN semiconductor in order to propose a convenient light propagation device since their laser diodes are a reality nowadays and constitutes a first step to develop future all-optical devices. Independently of the wavelength, the
