Sensitivity-Based Structural Optimal Design With Bi-Directional Beam Propagation Method for Photonic Devices in High-Index-Contrast Waveguides

This paper presents structural optimization based on sensitivity analysis exploiting a bi-directional beam propagation method (Bi-BPM) to design efficiently passive components in high-index-contrast optical waveguides. In this study, the Bi-BPM based on scaled-version Denman-Beavers iteration (S-DBI) with branch-cut technique, and scattering operator formulation (SO-Bi-BPM) is employed to execute stable, accurate wave-propagation analysis. Comparing three computation approaches of sensitivity with respect to design variables, efficient way of sensitivity analysis is revealed when the SO-Bi-BPM is used. The application range of the presented design approach is studied by designing a wavelength filter with waveguide grating, and a polarizer based on 1D photonic crystal (1D-PhC).