Compact Single-Mode Silicon Hybrid Rib/Strip Waveguide With Adiabatic Bends

We report a low-loss, hybrid silicon waveguide geometry that consists of straight rib sections with a propagation loss of 0.27 +/- 0.012 dB/cm and compact photonic wire bends. The rib and wire waveguides are both single mode and connected through a short double-etched linear taper section. To reduce bend losses, circular bends were combined with variable adiabatic seminatural spline shapes with only a limited footprint penalty.