Design of Compact TE-Polarized Mode-Order Converter in Silicon Waveguide With High Refractive Index Material

We propose and numerically demonstrate a design of bidirectional transverse electric (TE) polarized mode-order converter based on silicon-on-insulator platform. This converter is realized by introducing high refractive index material inlaid in a silicon slab waveguide. Simulated by three-dimensional finite-difference time-domain method, the forward (TE0 to TE1-like conversion) transmittance reaches approximately 88.2%, while the backward value (TE1 to TE0-like conversion) is about 89.4% at the wavelength of 1550 nm. The footprint of this converter is as small as 0.95 × 1.5
μ
m
²
. Fabrication tolerance analysis demonstrates satisfactory robustness. Moreover, we present a polarization-independent converter with slightly modified geometry. The transmittance keeps above 87.2% within the wavelength range from 1500 nm to 1600 nm for both TE and transverse magnetic modes. These devices are expected to contribute to the on-chip mode division multiplexing.