Developments in integrated photonics have led to stable, compact and broadband comb generators that support a wide range of applications including communications¹, ranging², spectroscopy³, frequency metrology⁴, optical computing^5,6 and quantum information^7,8. Broadband optical frequency combs can be generated in electro-optical cavities, where light passes through a phase modulator multiple times while circulating in an optical resonator^9,10,11,12. However, broadband electro-optic frequency combs are currently limited by low conversion efficiencies. Here we demonstrate an integrated electro-optic frequency comb with a conversion efficiency of 30% and an optical span of 132 nm, based on a coupled-resonator platform on thin-film lithium niobate¹³. We further show that, enabled by the high efficiency, the device acts as an on-chip femtosecond pulse source (336 fs pulse duration), which is important for applications in nonlinear optics, sensing and computing. As an example, in the ultrafast and high-power regime, we demonstrate a frequency comb with simultaneous electro-optic and third-order nonlinearity effects. Our device paves the way for practical optical frequency comb generators and provides a platform to investigate new regimes of optical physics that simultaneously involve multiple nonlinearities.

集成光子学的发展导致稳定、紧凑和宽带梳状发生器支持广泛的应用，包括通信¹、测距²、光谱³、频率计量⁴、光学计算^5,6和量子信息^7,8。宽带光学频率梳可以在电光腔中产生，其中光多次通过相位调制器，同时在光学谐振器中循环^9,10,11,12. 然而，宽带电光频率梳目前受到低转换效率的限制。在这里，我们展示了一个集成电光频率梳，其转换效率为 30%，光学跨度为 132 nm，基于薄膜铌酸锂^{13上的耦合谐振器平台}. 我们进一步表明，由于效率高，该器件可用作片上飞秒脉冲源（336 fs 脉冲持续时间），这对于非线性光学、传感和计算中的应用非常重要。例如，在超快和高功率状态下，我们展示了同时具有电光和三阶非线性效应的频率梳。我们的设备为实用的光学频率梳发生器铺平了道路，并提供了一个平台来研究同时涉及多个非线性的光学物理的新机制。