Modeling reflections induced by waveguide transitions

Reflections generated along optical waveguidesmay result in detrimental effects and deterioration of the circuit performances. In this work we propose a fast and accurate circuit model to predict the reflection induced by a waveguide discontinuity. The model is based on a variational approach of the Fresnel expression of the reflectivity. After theoretical description, the model is applied to two different interfaces: a waveguide transition inducing very low reflections and a reflective chip facet. A comparison with experimental results and electromagnetic simulations is shown, demonstrating the accuracy of the proposed method.