High-power electrically pumped microcombs

Integrated microcombs are promising for numerous applications that require a small footprint, high output power and high efficiency, such as data communications, sensing and spectroscopy. Electrically pumped microcombs have been recently demonstrated via the integration of gain chips with high-quality-factor integrated resonators. However, the overall optical power remains well below what is necessary for practical solutions. Here we demonstrate high-power electrically pumped Kerr-frequency microcombs by integrating a low-coherence source with high output power and silicon nitride ring resonators. We design the resonators with normal group velocity dispersion and leverage self-injection locking in the nonlinear regime for generating high on-chip power combs whereas, simultaneously, purifying the coherence of the pump source. We show microcombs with total on-chip power levels up to 158 mW and comb lines with an intrinsic linewidth as narrow as 200 kHz. We demonstrate more than twice the number of comb lines exceeding 100 μW and an order-of-magnitude higher on-chip power levels compared with previously reported results. Our novel electrically pumped microcomb source has the size, power and linewidth required for data communications, and could strongly impact other areas such as high-performance computing and ubiquitous devices for spectral-sensing and time-keeping applications.