Three-Octave Supercontinuum Generation Using SiO2 Cladded Si3N4 Slot Waveguide With All-Normal Dispersion

We investigate a silicon nitride (Si
₃
N
₄
) horizontal slot waveguide with silicon dioxide (SiO
₂
) cladding, which can achieve a flat and low normal dispersion of -15.56 ps/(nm·km) over a 3270-nm wavelength range from 1170 to 4440 nm, covering a 1.9 octave bandwidth. By launching a 100-fs 90-kW hyperbolic secant input pump pulse, a three-octave supercontinuum (SC) from 504 to 4229 nm can be generated using a 5-mm long waveguide. The generated SC spectrum is highly coherent, as it is mainly expanded by self-phase modulation (SPM) and optical wave breaking (OWB) in all-normal dispersion regime. The degree of coherence can achieve >0.99 from 1250 to 4300 nm. Therefore, the proposed waveguide could potentially serve as a key element in the on-chip broadband source for silicon photonic platform.