O-Band Platicon Microcomb Generation Using Laser Self-Injection Locking

The development of high-performance, low-cost O-band multi- wavelength light sources has become increasingly critical, largely driven by the exponential bandwidth growth in short-reach optical communications, along with applications such as optical coherence tomography and time-resolved spectroscopy. Quantum dot mode-locked lasers exhibit distinct advantages including low threshold current, intrinsic repetition rate stability, and ultra-broad gain bandwidth, yet they are constrained by limited channel counts and broad linewidths. While O-band dissipative Kerr soliton microcombs operating in the anomalous dispersion regime offer a promising alternative, they suffer from low pump-to-comb conversion efficiency and fabrication challenges. To overcome these bottlenecks, we demonstrate a high-performance, 200-GHz-spacing O-band platicon microcomb with a high conversion efficiency of 17.3%, achieved via laser self-injection locking (SIL) to a high-quality-factor, normal-dispersion, 300-nm-thick silicon nitride microresonator without specialized dispersion engineering. Benefiting from laser SIL mechanism, the pump phase noise is significantly suppressed, resulting in a narrow intrinsic linewidth of 634.7 Hz. This work establishes a practical pathway toward scalable and energy-efficient O-band multi- wavelength light sources for advanced applications.