Chip-based self-referencing using integrated lithium niobate waveguides
Chip-based self-referencing using integrated lithium niobate waveguides
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DOI：
10.1364/optica.392363
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发表时间：
2020-03
期刊：
影响因子：
10.4
通讯作者：
Yoshitomo Okawachi;Mengjie Yu;B. Desiatov;Bok Young Kim;T. Hansson;Marko Lonvcar;A. Gaeta
中科院分区：
文献类型：
--
作者：
Yoshitomo Okawachi;Mengjie Yu;B. Desiatov;Bok Young Kim;T. Hansson;Marko Lonvcar;A. Gaeta
通过自参考测量和稳定载波包络偏移频率f_{\textrm{CEO}}$对于光学频率梳产生至关重要，光学频率梳产生革命性地改变了精密频率计量学、光谱学和光学时钟。在过去的十年中，芯片级平台的发展使紧凑的集成波导能够产生超连续谱。然而，迫切需要一种片上自参考系统，其适应于不同的泵浦波长，需要低脉冲能量，并且不需要复杂的处理。在这里，我们证明了有效的载波包络偏移频率f_{CEO}$稳定的锁模激光器，只有107 pJ的脉冲能量通过自参考在集成的锂离子波导。我们实现了一个$f$-$2f$干涉仪，通过二次谐波产生和随后的超连续谱产生在一个单一的色散工程波导与稳定性能相当于一个传统的片外模块。在70 nm的泵浦波长范围内测量$f_{\textrm{CEO}}$ beatnote。我们从理论上研究我们的系统使用一个单一的非线性包络方程的贡献，从二阶和三阶非线性。我们的模型揭示了丰富的超宽带非线性动力学，并证实，最初的二次谐波产生，然后与剩余的泵超连续谱产生是负责产生一个强大的$f_{\textrm{CEO}}$信号相比，传统的$f$-$2f$干涉仪。我们的技术提供了一个高度简化的系统，该系统坚固耐用，成本低，适用于研究实验室以外的精密计量。
The measurement and stabilization of the carrier-envelope offset frequency $f_{\textrm{CEO}}$ 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 carrier-envelope offset frequency $f_{\textrm{CEO}}$ stabilization of a modelocked laser with only 107 pJ of pulse energy via self-referencing in an integrated lithium niobate waveguide. We realize an $f$-$2f$ 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 $f_{\textrm{CEO}}$ 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 $f_{\textrm{CEO}}$ signal as compared to a traditional $f$-$2f$ interferometer. Our technology provides a highly-simplified system that is robust, low cost, and adaptable for precision metrology for use outside a research laboratory.