The recent advancement in lithium-niobite-on-insulator (LNOI) technology is opening up new opportunities in optoelectronics, as devices with better performance, lower power consumption and a smaller footprint can be realised due to the high optical confinement in the structures. The LNOI platform offers both large χ⁽²⁾ and χ⁽³⁾ nonlinearities along with the power of dispersion engineering, enabling brand new nonlinear photonic devices and applications for the next generation of integrated photonic circuits. However, Raman scattering and its interaction with other nonlinear processes have not been extensively studied in dispersion-engineered LNOI nanodevices. In this work, we characterise the Raman radiation spectra in a monolithic lithium niobate (LN) microresonator via selective excitation of Raman-active phonon modes. The dominant mode for the Raman oscillation is observed in the backward direction for a continuous-wave pump threshold power of 20 mW with a high differential quantum efficiency of 46%. We explore the effects of Raman scattering on Kerr optical frequency comb generation. We achieve mode-locked states in an X-cut LNOI chip through sufficient suppression of the Raman effect via cavity geometry control. Our analysis of the Raman effect provides guidance for the development of future chip-based photonic devices on the LNOI platform.

绝缘体上锂铌矿（LNOI）技术的最新进展为光电子学领域开辟了新的机遇，由于结构中的高光学限制，可以实现性能更好、功耗更低和占地面积更小的器件。 LNOI 平台提供大的χ ⁽²⁾和χ ⁽³⁾非线性以及色散工程的强大功能，为下一代集成光子电路提供全新的非线性光子器件和应用。然而，拉曼散射及其与其他非线性过程的相互作用尚未在色散工程 LNOI 纳米器件中得到广泛研究。在这项工作中，我们通过拉曼活性声子模式的选择性激发来表征单片铌酸锂（LN）微谐振器中的拉曼辐射光谱。对于 20 mW 的连续波泵浦阈值功率和 46% 的高微分量子效率，在向后方向观察到拉曼振荡的主模式。我们探讨了拉曼散射对克尔光学频率梳生成的影响。我们通过腔几何控制充分抑制拉曼效应，在 X 切割 LNOI 芯片中实现锁模状态。我们对拉曼效应的分析为未来在 LNOI 平台上开发基于芯片的光子器件提供了指导。