The measurement and stabilization of the carrier–envelope offset frequency ${f_{{\rm CEO}}}$ via self-referencing is paramount for optical frequency comb generation, which has revolutionized precision frequency metrology, spectroscopy, and optical clocks. Over the past decade, the development of chip-scale platforms has enabled compact integrated waveguides for supercontinuum generation. However, there is a critical need for an on-chip self-referencing system that is adaptive to different pump wavelengths, requires low pulse energy, and does not require complicated processing. Here, we demonstrate efficient ${f_{{\rm CEO}}}$ stabilization of a modelocked laser with only 107 pJ of pulse energy via self-referencing in an integrated lithium niobate waveguide. We realize an $f \text{-} {2\!f}$ interferometer through second-harmonic generation and subsequent supercontinuum generation in a single dispersion-engineered waveguide with a stabilization performance equivalent to a conventional off-chip module. The ${f_{{\rm CEO}}}$ beatnote is measured over a pump wavelength range of 70 nm. We theoretically investigate our system using a single nonlinear envelope equation with contributions from both second- and third-order nonlinearities. Our modeling reveals rich ultrabroadband nonlinear dynamics and confirms that the initial second-harmonic generation followed by supercontinuum generation with the remaining pump is responsible for the generation of a strong ${f_{{\rm CEO}}}$ signal as compared to a traditional $f \text{-} {2\!f}$ interferometer. Our technology provides a highly simplified system that is robust, low in cost, and adaptable for precision metrology for use outside a research laboratory.

中文翻译：

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使用集成铌酸锂波导的基于芯片的自参考

通过自参考的载波-包络偏移频率$ {f _ {{\ rm CEO}}} $的测量和稳定对于光频率梳的产生至关重要，它彻底改变了精确的频率计量学，光谱学和光钟。在过去的十年中，芯片级平台的发展使紧凑的集成波导能够产生超连续谱。但是，迫切需要一种片上自参考系统，该系统可适应不同的泵浦波长，要求低脉冲能量并且不需要复杂的处理。在这里，我们展示了通过集成的铌酸锂波导中的自参考，仅具有107 pJ脉冲能量的锁模激光器的有效$ {f _ {{\ rm CEO}}} $稳定。我们意识到通过二次谐波产生和随后的超连续谱产生的$ f \ text {-} {2 \！f} $干涉仪，在单个色散工程波导中具有稳定的性能，相当于传统的片外模块。的$ {F _ {{\ RM CEO}}} $ beatnote上方的泵浦波长范围的70处测量。从理论上讲，我们使用具有二阶和三阶非线性贡献的单个非线性包络方程来研究系统。我们的模型揭示了丰富的超宽带非线性动力学，并证实了与传统方法相比，最初的二次谐波产生，其后是超连续谱，其余泵浦产生了强烈的$ {f _ {{\ rm CEO}}} $信号。$ f \ text {-} {2 \！f} $干涉仪。我们的技术提供了高度简化的系统，该系统功能强大，成本低廉，并且适合在研究实验室之外使用的精密计量。