High-power electrically pumped microcombs

This paper discusses the development of a high-power, electrically pumped Kerr-frequency microcomb system that integrates a low-coherence multimode laser with silicon nitride (Si₃N₄) resonators. The research addresses the key challenge of achieving sufficient optical power from microcombs, which is crucial for applications like data communications, spectroscopy, and sensing.

In the study, the authors show that by using self-injection locking in normal group velocity dispersion (GVD) resonators, they can generate microcombs with high on-chip power levels of up to 158 mW. These microcombs also exhibit narrow linewidths, as low as 200 kHz, making them suitable for high-precision applications. This represents a significant advancement, as it exceeds previous records for on-chip power and the number of comb lines exceeding 100 μW.

The system utilizes a multimode III-V laser, which is coupled to a Si₃N₄ chip through a custom-designed waveguide taper. The resulting device demonstrates more efficient comb generation and higher output power compared to previous approaches that relied on high-coherence pumps. The authors also show that the frequency comb lines produced have narrow linewidths and exhibit high stability, which is essential for practical applications in optical communications and sensing.

One of the key findings is that by optimizing the feedback phase and using integrated heaters for resonance detuning, the system can access coherent comb states efficiently. This approach, utilizing low-coherence lasers, allows for a scalable solution to achieving high-power Kerr-frequency combs with narrow linewidths and high efficiency. The paper concludes that this electrically pumped microcomb system can impact various fields, including data communications, high-performance computing, and quantum technologies, by reducing size, power consumption, and cost.