Large-bandwidth ultra-low-loss guiding in bi-periodic photonic crystal waveguides

For the first time, we experimentally demonstrate ultra-low-loss guiding in bi-periodic photonic crystal waveguides over a large bandwidth of more than 60 nm. In such bi-periodic waveguides, we achieve a propagation loss very similar to that of a dielectric ridge waveguide, which indicates that the dominant loss mechanism in these bi-periodic waveguides is due to fabrication imperfections.