Three-mode synthesis of slab Gaussian beam in ultra-low-loss in-plane nanophotonic silicon waveguide crossing

We demonstrate experimentally a fundamentally new low-loss silicon nanophotonic in-plane crossing. The crossing operation uses a three-mode synthesis of a 1-D Gaussian beam. The measured loss is 0.007 dB ± 0.004 dB, which is the lowest reported loss for silicon waveguide crossings.