A COMPARISON BETWEEN DIFFERENT PROPAGATIVE SCHEMES FOR THE SIMULATIONOF TAPERED STEP-INDEX SLAB WAVE-GUIDES

The performance and accuracy of a number of propagative algorithms are compared for the simulation of tapered high contrast step index slab waveguides. The considered methods include paraxial as well as nonpara xial formulations of optical field propagation. In particular attentio n is paid to the validity of the paraxial approximation, To test the i nternal consistency of the various methods the property of reciprocity is verified and it is shown that for the paraxial algorithms the reci procity can only be fulfilled if the paraxial approximation of the pow er flux expression using the Poynting vector is considered. Finally, m odeling results are compared with measured fiber coupling losses for a n experimentally realized taper structure.