Ultra Low Loss Waveguide Transitions for Reticle-Scale Silicon Nanophotonic Routing

Abstract

We report compact and low loss silicon nanophotonic waveguide transitions, to connect different cross-sections of routing waveguide in large photonic integrated circuits. 25-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>-long tapers shaped as a stretched sinusoid had 0.029 &x00B1; 0.002 dB absolute loss between single-mode strip and multi-mode rib waveguides. 10-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>-long adapters of concave elliptic shape had 0.002 &x00B1; 0.001 dB absolute loss between single-mode strip and rib waveguides, the lowest reported loss for such adapters.