Nonlinear totally reflecting prism coupler: thermomechanic effects and intensity-dependent refractive index of thin films.

Starting with an accurate linear electromagnetic theory of a totally reflecting prism coupled to a dielectric waveguide, we implement a numerical technique to take into account optogeometric perturbations in stratified media. We calculate both the reflected fields in intensity on the prism base (near field) and in infinity (far field) for an incident Gaussian beam. The study of the variations of the intensity in the reflected beam (near and far fields) versus light power shows thermoinduced dilation of the prism and an intensity-dependent refractive index of thin films composed of tantalium pentoxyde and titanium dioxide.