Wen Hao, Wang Jun, Zhu Liying, Shi Lei, Zhang Xinliang
Opt Lett. 2025 Jun 1;50(11):3692-3695. doi: 10.1364/OL.564090.
Integrated optical frequency combs (OFCs) and femtosecond pulse sources play pivotal roles in advancing optical communications, ranging, and spectroscopy. So far, most chip-scale OFCs are based on semiconductor mode-locked lasers or Kerr nonlinearity in microresonators. However, these approaches face inherent limitations in operation wave band and repetition rate tunability. Here, we demonstrate broadband and flat-top integrated electro-optic (EO) frequency combs by cascading one intensity modulator and two phase modulators on a thin-film lithium niobate chip. The measured EO combs feature over 70 comb lines within the 10-dB bandwidth, continuously tunable repetition rate from 5 GHz to 25 GHz, and central wavelength range over 120 nm. In addition, we obtain femtosecond pulses at different repetition rates with the narrowest pulse width of 565 fs. Our work paves the way for future compact, cost-effective, and reconfigurable on-chip light sources.
集成光学频率梳（OFCs）和飞秒脉冲源在推动光通信、测距和光谱学发展方面发挥着关键作用。到目前为止，大多数芯片级OFCs基于半导体锁模激光器或微谐振器中的克尔非线性效应。然而，这些方法在工作波段和重复频率可调性方面面临固有限制。在此，我们通过在薄膜铌酸锂芯片上级联一个强度调制器和两个相位调制器，展示了宽带平顶集成电光（EO）频率梳。所测量的电光频率梳在10 dB带宽内具有超过70条梳状谱线，重复频率可在5 GHz至25 GHz之间连续调谐，中心波长范围超过120 nm。此外，我们获得了不同重复频率的飞秒脉冲，最窄脉冲宽度为565 fs。我们的工作为未来紧凑、经济高效且可重构的片上光源铺平了道路。
