AWG-Based Monolithic $4 \times 12$ GHz Multichannel Harmonically Mode-Locked Laser

We report a novel arrayed waveguide grating (AWG)-based
$4\,\times \,12$
GHz multichannel harmonically mode-locked semiconductor laser operating near 1535 nm, which was realized by monolithically integrating a semiconductor optical amplifier (SOA) array, a set of passive optical delay lines, an AWG with 400 GHz channel spacing, a saturable absorber, and a common output SOA. Our device layout and fabrication were completed on the European JePPIX InP photonic integration platform, based on the multiproject wafer run foundry approach. We demonstrated four wavelength channels operating in the fifth harmonic mode-locking regime. Channel repetition rate of 12 GHz and 3-dB RF linewidth as narrow as 6 kHz were obtained. The exhibited performance makes our device a very promising candidate as an ultracompact multichannel light source for future hybrid optical time and wavelength division multiplexing, high-speed photonic analog-to-digital conversion, and optical clock recovery applications.