Kaixuan Zhu, Xinrui Luo, Yuanlei Wang, Ze Wang, Tianyu Xu, Du Qian, Yinke Cheng, Junqi Wang, Haoyang Luo, Yanwu Liu, Xing Jin, Zhenyu Xie, Xin Zhou, Min Wang, Jian-Fei Liu, Xuening Cao, Ting Wang, Shui‐Jing Tang, Qihuang Gong, Bei-Bei Li, Qi-Fan Yang
The drive to miniaturize optical frequency combs for practical deployment has spotlighted microresonator solitons as a promising chip-scale candidate. However, these soliton microcombs could be very power-hungry when their span increases, especially with fine comb spacings. As a result, realizing an octave-spanning comb at microwave repetition rates for direct optical-microwave linkage is considered not possible for photonic integration due to the high power requirements. Here, we introduce the concept of resonant-coupling to soliton microcombs to reduce pump consumption significantly. Compared to conventional waveguide-coupled designs, we demonstrate (i) a threefold increase in spectral span for high-power combs and (ii) up to a tenfold reduction in repetition frequency for octave-spanning operation. This configuration is compatible with laser integration and yields reliable, turnkey soliton generation. By eliminating the long-standing pump-power bottleneck, microcombs will soon become readily available for portable optical clocks, massively parallel data links, and field-deployable spectrometers.