铌酸锂晶体是一种综合性质优异的多功能光学材料。在过去几十年里,对铌酸锂晶体的研究一直是光学研究的热点之一。近年来发展起来的绝缘体上铌酸锂(LNOI),亦称为铌酸锂薄膜(LNTF),在光学领域被公认为是一项变革性技术。基于LNOI的集成光子器件让铌酸锂晶体又焕发了新生命,再次成为集成光子学的研究焦点。作为最优秀的非线性晶体之一,铌酸锂薄膜在频率转换方面是其他薄膜材料无法替代的。总结了基于铌酸锂薄膜的非线性频率转换最新研究进展,包括二阶非线性、三阶非线性、级联非线性和光学频率梳等,最后对LNOI平台上光子集成回路(PIC)的前景进行了展望。

The lithium niobate crystal is a multifunctional optical material with excellent comprehensive properties. For the past decades, lithium niobate crystal has attracted significant attention in optics researches. Recently, lithium niobate on insulator (LNOI), also known as lithium niobate thin film (LNTF), has been considered as a revolutionary technology in optics that rejuvenates lithium niobate for LNOI-based integrated photonics. A LNTF is irreplaceable in frequency conversion since it is one of the best nonlinear crystals. In this study, we summarize the most recent progress of LNTF in nonlinear frequency conversions, such as second-order nonlinearities, third-order nonlinearities, cascaded nonlinearities, and optical frequency comb. Finally, we present the prospect for photonic integrated circuits (PIC) on the LNOI platform.