Boardband Coherent Comb Generation in an All-NormalDispersion AlGaAs-on-Sapphire Waveguide

We experimentally demonstrate coherent comb generation in a 5-mm long all-normal-dispersion AlGaAs-on-sapphire waveguide with a 47% pump-to-comb conversion efficiency. We achieve a 20-dB bandwidth of 24.5 THz covering from the S- to U-band wavelength ranges.