On-chip octave-spanning flat supercontinuum in all-normal-dispersion silicon nitride waveguides

On-chip supercontinuum generation has attracted a great deal of attention in recent years. Among silicon-based materials, silicon nitride represents an attractive solution for on-chip supercontinuum generation due to its wide transparency window, relatively high Kerr nonlinearity, and negligible two-photon absorption. In this paper, we achieve a flat allnormal dispersion profile in the silicon nitride platform, with a flat dispersion from 600 nm to 2760 nm. Using the proposed waveguide, an ultra-flat (-6 dB) high-coherent octave-spanning supercontinuum covering from 638 nm to 1477 nm can be generated by launching a 250-fs 30-kW input pulse centered at 960 nm. The proposed supercontinuum is of great importance for achieving high-resolution optical coherence tomography and fully stabilized frequency comb sources.